tag:theconversation.com,2011:/id/topics/freshwater-5873/articlesFreshwater – The Conversation2024-01-17T21:52:45Ztag:theconversation.com,2011:article/2204552024-01-17T21:52:45Z2024-01-17T21:52:45ZRipple effect: How public attitudes can shift governments toward sustainable, and resilient, water systems<p>With all the negative news coming out about climate change, its impacts and its possible trajectory in the not-so-distant future, it can be difficult to maintain hope for a brighter future.</p>
<p>The last few years have been challenging, even for optimists, with international climate meetings like the recent COP28 in Dubai emphasizing <a href="https://www.wri.org/insights/explaining-global-stocktake-paris-agreement">how far we are from where we need to be in terms of climate action</a>. Meanwhile, reports like IPBES’ global biodiversity report provide <a href="https://www.ipbes.net/global-assessment">strong evidence for the accelerating deterioration of nature and its benefits</a>. </p>
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Read more:
<a href="https://theconversation.com/2023-was-the-hottest-year-in-history-and-canada-is-warming-faster-than-anywhere-else-on-earth-220997">2023 was the hottest year in history — and Canada is warming faster than anywhere else on earth</a>
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<p>It can feel like there is not enough momentum to move quickly enough to slow climate change and stave off its worst impacts. However, our recent work provides a point of hope and evidence for optimism.</p>
<h2>Understanding resilience</h2>
<p>We are researchers with expertise in psychology, sustainability and environmental governance. Our study assessed the attitudes of the general public towards a resilience-based approach to environmental decision-making, with a special focus on water. </p>
<p>Resilience is the ability to respond to disturbances (like climate change impacts) by resisting change, adapting or transforming, if needed, for the well-being of humans and ecosystems. </p>
<p>There are <a href="https://doi.org/10.1146/annurev-environ-051211-123836">seven principles that support resilience</a> that range from promoting connectivity of human and natural systems, to creating inclusive decision-making processes, to being willing to experiment with new approaches and learn from them, even if they are not entirely successful.</p>
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<figcaption><span class="caption">An overview of the basic principles of climate change adaptation and resilience produced by the IPCC in 2022.</span></figcaption>
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<p>We can <a href="https://doi.org/10.1016/j.indic.2023.100249">assess these principles</a> and each of them contributes to resilience in unique and critically important ways. How we <a href="https://theconversation.com/the-meaning-of-environmental-words-matters-in-the-age-of-fake-news-106050">understand what resilience means matters</a>. </p>
<p>Some understand it to be only the ability to resist change, which is not sufficient for what the world needs in this moment. Beyond resisting, we must also adapt, and potentially, transform. However, resilience can also be used as a tool to deflect blame and responsibility for supporting disproportionately affected groups.</p>
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<a href="https://theconversation.com/the-unfairness-of-the-climate-crisis-podcast-192469">The unfairness of the climate crisis — Podcast</a>
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<p>Many organizations and international bodies, including the <a href="https://www.ipcc.ch/report/sixth-assessment-report-cycle/">IPCC</a>, <a href="http://hdl.handle.net/10986/34780">the World Bank</a> and the <a href="https://unfccc.int/topics/adaptation-and-resilience/the-big-picture/introduction">United Nations Climate Change Secretariat</a>, argue that we need to integrate resilience — including adaptation and transformation — into how we govern, make strategic decisions and take action moving forward.</p>
<p>We need resilience because we are dealing with unprecedented environmental change and the drivers and impacts of this change are highly intertwined, making governance a complex task. Resilience can meet the challenge of complexity. In our work, we focus on resilience in surface freshwater governance, specifically. </p>
<h2>Public attitudes</h2>
<p>How we govern is determined by many factors, <a href="https://doi.org/10.1177/106591290305600103">including public attitudes</a>. </p>
<p>As members of the public, we can vote, protest, communicate directly with elected officials, write opinion pieces for news outlets, talk to our neighbours and friends, and educate our children. We have multiple ways to influence decision-making, and our attitudes play an important role in the messages we send through those spheres of influence.</p>
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Read more:
<a href="https://theconversation.com/court-decision-in-youth-climate-lawsuit-against-ontario-government-ignites-hope-206275">Court decision in youth climate lawsuit against Ontario government ignites hope</a>
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<p>We measured the attitudes of the general public in six countries representing the Global North and South with a study focused on resilience and water governance. We offered participants in our survey a vignette, or short scenario, about a water issue. </p>
<p>Participants answered a series of questions about the vignette. For each question, they had four options, representing a spectrum of support for resilience, from no support to full support.</p>
<p>Across six countries (Canada, the United States, Australia, the United Kingdom, India and South Africa) there was <a href="https://doi.org/10.1017/sus.2023.23">moderate to strong support for a resilience-based approach to water governance</a>. These findings suggest a positive outlook on public attitudes towards resilience-centred water governance, both now and especially for the future.</p>
<p>The best news from the study was that more than half of the participants across all countries showed the potential for strengthening their support for a more resilient approach to water governance. </p>
<p>We measured potential for growth by asking participants to select all of the options they considered acceptable for each question, before choosing their most preferred option. If participants selected an option that demonstrated stronger support for resilience than the one they most preferred, this signalled room for improving their support.</p>
<h2>Taking action</h2>
<p>We are encouraged by these results and how consistent they were across multiple countries that have different water issues, cultures and political leadership. We accounted for some of these differences by providing vignettes that dealt with a range of water issues, from flooding to drought to infrastructure concerns. </p>
<p>Even with differing water issues and cultures factored in, attitudes were consistent, and so was the potential to strengthen support for water resilience.</p>
<p>We feel that these results serve as a hopeful message to those who might be feeling discouraged or pessimistic about our shared future. There are many whose attitudes support resilience-based approaches to governance, and this is a fact worth celebrating.</p>
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Read more:
<a href="https://theconversation.com/canadians-are-unprepared-for-natural-hazards-heres-what-we-can-do-about-it-201863">Canadians are unprepared for natural hazards. Here's what we can do about it</a>
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<p>We also share this message with those in policy leadership positions, like the <a href="https://www.canada.ca/en/environment-climate-change/services/water-overview/canada-water-agency.html">Canada Water Agency</a>.</p>
<p>The public is supportive of approaches that will improve the resilience of water systems and strengthen the well-being of humans and the ecosystems upon which we all depend.</p><img src="https://counter.theconversation.com/content/220455/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Julia Baird receives funding from SSHRC and the Canada Research Chairs program. She is affiliated with the Canadian Coalition for Healthy Waters as an academic advisor.</span></em></p><p class="fine-print"><em><span>Gary Pickering receives funding from the Social Sciences and Humanities Research Council of Canada.</span></em></p><p class="fine-print"><em><span>Gillian Dale does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The results of a new study are clear: resilient water governance systems are effective and enjoy strong public support. The time is now to build resilience into our global water systems.Julia Baird, Associate Professor and Canada Research Chair in Human Dimensions of Water Resources and Water Resilience, Brock UniversityGary Pickering, Professor, Biological Sciences and Psychology, Brock UniversityGillian Dale, Research fellow, Environmental Sustainability Research Centre, Brock UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2157532023-12-15T13:18:59Z2023-12-15T13:18:59ZHow to provide reliable water in a warming world – these cities are testing small-scale treatment systems and wastewater recycling<figure><img src="https://images.theconversation.com/files/564629/original/file-20231209-21-270hhg.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C5615%2C3715&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Water treatment doesn't have to be one large, citywide system.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/kitchen-sink-with-running-water-royalty-free-image/168583229">Deepblue4you/E+ via Getty Images</a></span></figcaption></figure><p>A lot can go wrong in a large urban water system. Pumps malfunction. Valves break. Pipes leak. Even when the system is functioning properly, water can sit in pipes for long periods of time. Water shortages are also a <a href="https://e360.yale.edu/features/on-site-distributed-premise-graywater-blackwater-recycling">growing problem in a warming world</a>, as communities across the Southwestern U.S. and in many developing nations are discovering. </p>
<p>That’s why cities have started experimenting with small-scale alternatives – including wastewater recycling and localized water treatment strategies known as decentralized or distributed systems.</p>
<p>I <a href="https://www.ccee.iastate.edu/liugroup-human-env-research/">study large- and small-scale water systems</a>, focusing on innovative system designs that allow local use of water sources that might otherwise go to waste. As technology improves, cities are discovering something that <a href="https://www.epa.gov/small-and-rural-wastewater-systems/about-small-wastewater-systems">rural communities have long known</a>: Small-scale water treatment, <a href="https://doi.org/10.1021/acs.est.1c04708">properly engineered</a>, can be cheaper and easier to maintain than a centralized system, and it can improve water security and <a href="https://doi.org/10.1088/1748-9326/7/2/024007">even the environment</a>.</p>
<h2>Cleaning water – nature’s lessons</h2>
<p>Almost all water has value and can be cleaned and put to use. </p>
<p>Nature does a <a href="https://www.youtube.com/watch?v=ZwQeTJEeedk">great job of cleaning water naturally</a> as it flows through the ground. The soil physically filters water, and chemical and biological processes help strip away contaminants over time. </p>
<p>Those processes <a href="https://smartwatermagazine.com/news/rice-university/making-wastewater-drinkable-again">can be mimicked</a> by water treatment plants and filters that are becoming increasingly effective. </p>
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<figcaption><span class="caption">An illustrated tour of how water treatment systems generally work.</span></figcaption>
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<p>Traditionally, cities have relied on <a href="https://infrastructurereportcard.org/cat-item/drinking-water-infrastructure/">centralized water systems</a> that treat freshwater from a river or aquifer at a central facility, then distribute it through a large network of pipes. But that infrastructure becomes increasingly vulnerable to disruptions as it ages. And climate change, water scarcity and population growth increase stress on the system.</p>
<p>So, some <a href="https://doi.org/10.3390/ijerph17239060">cities are experimenting</a> with what are known as distributed systems. These are small-scale water treatment, reclamation and recycling plants that are designed to collect, treat and reuse water in close proximity to both the source and the user. <a href="https://doi.org/10.3390/ijerph17239060">Some are separate operations</a>. Others are connected to the larger system in a hybrid model. </p>
<p>For example, a decentralized system might treat wastewater in an urban area and recycle it for reuse within that area by the same users, as <a href="https://www.epwater.org/about_us/newsroom/news_from_the_pipeline/new_facility_funds_help_lead_way_in_reuse">El Paso, Texas</a>, is doing. Or it could <a href="https://doi.org/10.1016/j.jenvman.2020.111639">collect storm runoff and wastewater</a> from homes and <a href="https://smartwatermagazine.com/news/orange-county-water-district/people-are-willing-get-over-yuck-factor-have-a-safe-and-reliable">redirect it specifically for irrigation or to recharge groundwater</a>, as <a href="https://www.austintexas.gov/faq/rainwater-harvesting">Austin, Texas</a>, and <a href="https://www.sfexaminer.com/archives/after-the-storm-how-san-francisco-utilizes-rainwater/article_2870a292-6576-5fb9-8eb3-caf14d853a79.html">San Francisco</a> do. </p>
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<figcaption><span class="caption">Water recycling in Windhoek, Namibia, where freshwater is scarce.</span></figcaption>
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<p><a href="https://www.umontpellier.fr/en/articles/ces-pays-qui-recyclent-les-eaux-usees-en-eau-potable">Windhoek, Namibia</a>, a city of about 430,000 people surrounded by an arid landscape, has been treating wastewater to achieve a drinking standard and returning it to homes since 1968 for all kinds of uses, including cooking and drinking. Storm water runoff, industrial water, wastewater and even agricultural runoff <a href="https://efcnetwork.org/one-water-approach-for-improvement-in-water-resource-management/">can be treated and recycled with modern technology</a> to become drinkable. California’s State Water Resources Control Board <a href="https://calmatters.org/environment/2023/12/california-rules-turn-sewage-into-drinking-water/">approved regulations</a> in December 2023 to eventually allow water systems there to convert wastewater to drinking water, following a similar move in Colorado. </p>
<p>All of these approaches, whether connected to the main system or as separate closed systems, can reduce the community’s overall demand for freshwater from rivers or aquifers.</p>
<h2>Technology is making more water more reusable</h2>
<p>Small-scale treatment can range from advanced filters inside individual homes to treatment at tanks serving clusters of homes or commercial, industrial and agricultural facilities. </p>
<p>Often, the treated water goes to <a href="https://doi.org/10.1088/1748-9326/aabef0">non-potable uses like toilet flushing</a> or to replenish groundwater. But <a href="https://doi.org/10.1016/j.wroa.2021.100094">advances in technology</a> are making these decentralized water systems more feasible and expanding their uses.</p>
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<img alt="A man stands on a walkway overlooking wastewater in a small treatment facility." src="https://images.theconversation.com/files/564627/original/file-20231209-25-52ol2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564627/original/file-20231209-25-52ol2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564627/original/file-20231209-25-52ol2p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564627/original/file-20231209-25-52ol2p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564627/original/file-20231209-25-52ol2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=493&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564627/original/file-20231209-25-52ol2p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=493&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564627/original/file-20231209-25-52ol2p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=493&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Murcia, Spain, an arid agriculture region, built dozens of water treatment plants to process and disinfect wastewater from the sewage system for reuse on farm fields. The plants use sand filters and ultraviolet rays. Almost all of the region’s wastewater is reused.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/responsible-for-exploitation-at-edar-water-treatment-news-photo/1258840091">Jose Jordan/STR/AFP via Getty Images</a></span>
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<p><a href="https://doi.org/10.1038/s41565-018-0203-2">Membrane-based and electrochemical processes</a> have shown great potential for recovering fresh water, nutrients – which can be used for fertilizer – and energy from wastewater. These processes include reverse osmosis, which pushes water through a semipermeable membrane to remove impurities, and electrodialysis, which uses an electric field.</p>
<p>Microbial fuel cells go a step further and use the microbes present in wastewater to both produce electricity and facilitate the treatment of wastewater simultaneously. Another energy recovery method involves capturing biogas, primarily methane, from decomposing organic matter in wastewater in the absence of oxygen.</p>
<p>Unlike conventional treatment technologies, which work on a large scale, these emerging treatment processes use modular designs that can be easily scaled up or down. </p>
<p>They can also be used to create hybrid systems by supplementing large centralized systems with treated water, particularly in arid regions where water supplies are scarce.</p>
<h2>How a hybrid system might help Houston</h2>
<p>To test how a hybrid system might help avoid water shortages due to disruptions to the system, my colleagues and I created <a href="https://www.nature.com/articles/s44221-023-00166-6">a model of Houston</a>, a city with 7,000 miles of pipelines and 2.2 million residents. We simulated the impact that different types of water outages can have on that large centralized water supply and how distributed sources could help reduce the impact. </p>
<p>Overall, we found that installing hybrid systems did a better job supplying water and avoiding low flows across the city than the centralized system alone, particularly in areas where low water pressure is common.</p>
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<img alt="An overhead view of 6 round water treatment tanks at a large water treatment facility next to solar panels." src="https://images.theconversation.com/files/564631/original/file-20231209-19-x7y8b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564631/original/file-20231209-19-x7y8b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=376&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564631/original/file-20231209-19-x7y8b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=376&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564631/original/file-20231209-19-x7y8b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=376&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564631/original/file-20231209-19-x7y8b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=473&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564631/original/file-20231209-19-x7y8b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=473&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564631/original/file-20231209-19-x7y8b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=473&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Large centralized water treatment plants can have thousands of miles of pipes and cause widespread problems when equipment fails. In smaller systems, there are fewer components that can go awry.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/aerial-view-solar-cells-near-a-wastewater-treatment-royalty-free-image/1423253122">Songphol Thesakit/Moment via Getty Images</a></span>
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<p>The pressurized flow from reclaimed water could also limit the spread of contamination from sources such as a terrorist attack in the vicinity of the reclaimed water source. </p>
<p>That doesn’t mean new water sources are risk-free, of course. Additional sources connecting to a large water system can also introduce new potential sources of contamination, so the design of the system is important.</p>
<p>Several <a href="https://doi.org/10.1029/2022WR033758">factors determine how effective distributed water can be</a>. Population and building density, local water demand, soil characteristics, climate conditions, infrastructure and the state of existing water infrastructure all play a role. Research indicates that regions with <a href="https://doi.org/10.1021/acs.est.1c04708">high energy demands</a> for water distribution, significant local water requirements and the capacity to reuse wastewater <a href="https://doi.org/10.1029/2022WR033758">stand to gain the most</a>. </p>
<p>Notably, <a href="https://smartwatermagazine.com/news/smart-water-magazine/san-franciscos-decentralised-approach-water-recycling">San Francisco has emerged as a pioneer</a> in <a href="https://e360.yale.edu/features/on-site-distributed-premise-graywater-blackwater-recycling">extreme decentralization</a>, with initiatives extending down to the individual building level. In some buildings, water tanks, filters and treatment in the basement make water <a href="https://www.cbsnews.com/sanfrancisco/news/reuse-system-turns-wastewater-at-san-francisco-high-rise-into-clean-water-soil-energy/">reusable for activities such as flushing toilets</a>. </p>
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<a href="https://images.theconversation.com/files/564628/original/file-20231209-17-26anzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The rooftop of a building looks like a park, with walking paths, trees and other plants." src="https://images.theconversation.com/files/564628/original/file-20231209-17-26anzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/564628/original/file-20231209-17-26anzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/564628/original/file-20231209-17-26anzm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/564628/original/file-20231209-17-26anzm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/564628/original/file-20231209-17-26anzm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/564628/original/file-20231209-17-26anzm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/564628/original/file-20231209-17-26anzm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">The Salesforce Transit Center in San Francisco filters wastewater from sinks, showers, toilets and other sources for reuse.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/davidyuweb/29062452107">David Yu/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
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<h2>What’s standing in the way?</h2>
<p>Despite the benefits, water reuse accounts for less than 1% of total water use in the U.S. today.</p>
<p><a href="https://doi.org/10.3389/fenvs.2021.633841">Public perceptions concerning recycled water</a> are one challenge, including <a href="https://decentralizedwater.waterrf.org/documents/04-DEC-2/04-DEC-2full.pdf">enduring skepticism</a> regarding the safety, reliability and appropriate use of reclaimed water.</p>
<p>Wastewater recycled properly is considered safe to drink and <a href="https://engineering.stanford.edu/magazine/cleanest-drinking-water-recycled">may even contain less toxic risk</a> than the sources of water we already drink. However, water that is not treated to the appropriate level <a href="https://nap.nationalacademies.org/read/13303/chapter/8#103">can pose significant human health risks</a>. A <a href="https://straitsresearch.com/report/decentralized-water-treatment-market">robust business model</a> is also <a href="https://www.wateronline.com/doc/best-practices-for-decentralized-wastewater-treatment-system-upgrades-and-replacements-0001">needed to make decentralized systems</a> cost-effective, coupled with a supportive governance structure.</p>
<p>As <a href="https://www.epa.gov/infrastructure/water-infrastructure-investments">federal funds</a> pour in to revitalize America’s water infrastructure, U.S. communities have a golden opportunity to bolster their large water systems with a decentralized approach. Globally, with climate change fueling extreme storms and making water supplies less reliable in many areas, small-scale decentralized systems could provide water security and increase water access in areas that are underserved today. </p>
<p><em>This article, originally published Dec. 15, 2023, has been updated with California’s new regulation.</em></p><img src="https://counter.theconversation.com/content/215753/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lu Liu does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Water shortages are one of the greatest problems created by a warming world. A decentralized water system is a compelling counterargument to the notion that bigger is better.Lu Liu, Assistant Professor of Civil, Construction and Environmental Engineering, Iowa State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2151312023-11-19T13:00:27Z2023-11-19T13:00:27Z‘Forever contaminant’ road salts pose an icy dilemma: Do we protect drivers or our fresh water?<p>As winter approaches, many communities in Canada and around the world arm themselves against icy roads and sidewalks with a time-honoured ally: road salt. For decades, applying road salt has been regarded as a simple but vital tool in countering the dangers of slippery road conditions, but the downsides of its use are apparent with implications that <a href="https://doi.org/10.1007/s11270-018-4060-2">extend beyond the cold months</a>. </p>
<p>Scientists have long known that the substance which has safeguarded us through the colder months poses a threat to aquatic life and drinking water quality. But now we are finding that this chemical also <a href="https://doi.org/10.1016/j.scitotenv.2022.157336">disrupts the delicate balance of oxygen and nutrients</a> in our freshwater lakes and ponds. </p>
<p>Road salt, commonly referred to as rock salt, is a mixture primarily composed of sodium chloride (NaCl). It is used to de-ice roads and highways during winter to enhance safety by preventing the formation of ice and reducing slippery conditions. Road salt persists as an environmental contaminant due to its chemical stability and the cyclic nature of its dispersal. </p>
<p>Introduced through activities like road de-icing, salts move from roads to surface water such as streams and lakes, groundwater, remaining indefinitely in the environment without significant degradation. The continual cycling and lack of substantial transformation underscore the long-term impact of sodium chloride as a “forever contaminant.”</p>
<p>With a growing awareness of its ecological repercussions, a critical dilemma emerges. Do we prioritize driver safety or acquatic ecosystem health?</p>
<h2>Negative impacts revisited</h2>
<p>The detrimental effects of road salt on aquatic ecosystems and drinking water supplies <a href="https://doi.org/10.1016/j.scitotenv.2021.150289">have long been recognized</a>. Its heavy application during winter months leads to a buildup of road salt ions in both soil and water bodies, altering their natural chemical composition. </p>
<p>These elevated salt concentrations can harm freshwater organisms and vegetation, change soil structure, and, when <a href="https://doi.org/10.1016/j.scitotenv.2023.166466">seeping into groundwater</a>, compromise the potable water supply of nearby communities.</p>
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<a href="https://theconversation.com/winter-road-salting-has-year-round-consequences-173621">Winter road salting has year-round consequences</a>
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<p><a href="https://doi.org/10.1016/j.scitotenv.2022.157336">Recent research</a> has shed light on a less conspicuous yet equally significant consequence of road salt usage: its contribution to oxygen depletion in lakes. The occurrence of <a href="https://doi.org/10.1029/2023JG007558">very low oxygen concentrations, or hypoxia, in a lake is generally attributed to an excessive input of nutrients, especially that of phosphorus</a>. </p>
<p>Nutrient enrichment can trigger algal blooms that, in turn, lower the oxygen level in the lake’s deeper waters. The continued expansion of hypoxic conditions deteriorates the lake’s water quality and may ultimately cause the die-off of most aquatic life. This nutrient-driven process, <a href="https://doi.org/10.5194/bg-14-3585-2017">known as eutrophication</a>, is affecting the ecological health of a growing number of lakes around the world.</p>
<h2>Salt and oxygen in water</h2>
<p><a href="https://doi.org/10.5194/egusphere-egu2020-16637">Phosphorus</a>, the nutrient frequently implicated in lake eutrophication, plays a multifaceted role in this scenario. <a href="https://doi.org/10.1016/j.scitotenv.2022.157336">Salinization</a> increases the density of the water reducing the mixing of the lake waters and. Consequently, this reduces the amount of oxygen that reaches the lake’s depths. </p>
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Read more:
<a href="https://theconversation.com/road-salt-makes-winter-driving-safer-but-what-does-it-do-to-the-environment-87860">Road salt makes winter driving safer, but what does it do to the environment?</a>
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<p>Oxygen depletion, paradoxically, favours the remobilization of phosphorus from the sediments accumulating at the bottom of the lake. That is, the sediments become an increasingly important <em>internal</em> source of phosphorus, escalating the nutrient enrichment of the lake. </p>
<p>In that way, salinization — driven by extensive road salt application — <a href="https://doi.org/10.1016/j.scitotenv.2022.157336">intensifies eutrophication symptoms</a> that are usually associated with phosphorus supplied to lakes from external sources in the surrounding landscape.</p>
<h2>Navigating the saline challenge</h2>
<p>Canada has been <a href="https://doi.org/10.1016/j.scitotenv.2021.151717">proactive in responding</a> to eutrophication. For instance, reduced phosphorus pollution in Lake Erie in the 1980s and 1990s led to significant <a href="https://doi.org/10.1029/2019WR025019">water quality improvements</a>. However, addressing accelerating salinization of lakes requires new thinking and innovative solutions that recognize the complexity of the issue. It’s not just de-icers, such as road salts, that need to be considered. </p>
<p><a href="https://doi.org/10.1098/rstb.2018.0019">Other sources of salt</a>, such as agricultural runoff, discharges from water softeners and other domestic activities and drainage from mine waste and geological salt deposits, are all part of the problem. Salinization is a <a href="https://doi.org/10.1073/pnas.1620211114">threat to water resources globally</a>, not just those of cold regions.</p>
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<figcaption><span class="caption">A brief overview of the process of eutrophication, produced by the National Oceanic and Atmospheric Administration.</span></figcaption>
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<p>Chloride, a key component of road salt, has earned the moniker of a “forever contaminant” <a href="https://doi.org/10.1016/j.scitotenv.2018.10.242">due to its persistence in soil and water systems</a>. When introduced into the environment, chloride ions readily dissolve into water <a href="https://doi.org/10.1016/j.scitotenv.2018.10.242">where they tend to remain</a>. </p>
<p>Over time, chloride not only accumulates in surface water bodies <a href="https://doi.org/10.1016/j.scitotenv.2023.166466">but also in groundwater</a>. In fact, ground (or subsurface) water has been identified as a persistent source of chloride to surface freshwater bodies, especially during the summer months. </p>
<p>While <a href="https://doi.org/10.2166/wqrjc.2011.105">proactive management practices have been introduced</a>, the accumulation of chloride and other problematic <a href="https://doi.org/10.1111/j.1747-6593.2012.00371.x">salt ions</a>, including sodium, in soil and water will require expensive and <a href="https://doi.org/10.2134/jeq2009.0108">time-consuming restoration efforts</a>. </p>
<h2>Paving the path to solutions</h2>
<p>To mitigate the impacts of salinization, evidence-based approaches are urgently required. Solutions and policy recommendations must promote the reduction of salt runoff from road salt applications and other sources, and establish effective and comprehensive monitoring programs. </p>
<p>We have much to learn from how we’ve successfully managed excessive nutrient pollution — these lessons can help inform salt management strategies that work hand in hand with water quality and climate change solutions.</p>
<p>One potential alternative to the application of road salts is to use other de-icers. This requires a cautious stance because, as history teaches us, replacing one troublesome chemical with another often comes with unexpected ecological consequences. </p>
<p>Thorough examination and research are vital to ensure that alternatives don’t inadvertently introduce new threats.</p>
<h2>Protecting people and ecosystems</h2>
<p>The stakes are high when it comes to road salts: compromised drinking water, shrinking aquatic habitats and long-term pollution from legacy salt stores in soil and groundwater requiring costly remediation. It’s imperative that research, investment and public awareness converge to address this challenge holistically. </p>
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Read more:
<a href="https://theconversation.com/to-make-less-harmful-road-salts-were-studying-natural-antifreezes-produced-by-fish-153087">To make less-harmful road salts, we're studying natural antifreezes produced by fish</a>
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<p>The impacts of road salt’s application extend far beyond the icy surfaces it’s intended to protect us from. As winter approaches, policy should work towards protecting our ecosystems and the many services they provide.</p><img src="https://counter.theconversation.com/content/215131/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jovana received support from the Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Partnerships Grant (STPGP 521515-18), and the Lake Futures project and Managing Urban Eutrophication Risks under Climate Change project within the Global Water Futures (GWF) program funded by the Canada First Research Excellence Fund (CFREF).</span></em></p><p class="fine-print"><em><span>David L Rudolph receives funding from the Natural Sciences and Engineering Research Council of Canada, the Ontario Ministry of the Environment, Conservation and Parks and the Regional Municipality of Waterloo. </span></em></p><p class="fine-print"><em><span>Fereidoun received support from the Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Partnerships Grant (STPGP 521515-18), and the Lake Futures project and Managing Urban Eutrophication Risks under Climate Change project within the Global Water Futures (GWF) program funded by the Canada First Research Excellence Fund (CFREF).</span></em></p><p class="fine-print"><em><span>Nancy received support from the Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Partnerships Grant (STPGP 521515-18), and the Lake Futures project and Managing Urban Eutrophication Risks under Climate Change project within the Global Water Futures (GWF) program funded by the Canada First Research Excellence Fund (CFREF).</span></em></p><p class="fine-print"><em><span>Philippe received support from the Natural Sciences and Engineering Research Council of Canada (NSERC) Strategic Partnerships Grant (STPGP 521515-18), and the Lake Futures project and Managing Urban Eutrophication Risks under Climate Change project within the Global Water Futures (GWF) program funded by the Canada First Research Excellence Fund (CFREF).</span></em></p><p class="fine-print"><em><span>Jiangyue Ju does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Increasing awareness of the dangers ‘forever chemical’ road salts pose to our fresh water systems highlights the urgent importance of finding new approaches to de-icing our roads.Jovana Radosavljevic, Postdoctoral Fellow, Ecohydrology Research Group, University of WaterlooDavid L Rudolph, Professor of Hydrogeology, Department of Earth & Environmental Sciences, University of WaterlooFereidoun Rezanezhad, Research Associate Professor, Department of Earth & Environmental Sciences, University of WaterlooJiangyue Ju, PhD Student in Earth and Environmental Sciences, University of WaterlooNancy Goucher, Knowledge Mobilization Specialist, University of WaterlooPhilippe Van Cappellen, Professor of Biogeochemistry and Canada Excellence Research Chair Laureate in Ecohydrology, University of WaterlooLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2162532023-11-08T13:37:55Z2023-11-08T13:37:55ZFresh water is a hidden challenge − and opportunity − for global supply chains<figure><img src="https://images.theconversation.com/files/558062/original/file-20231107-15-72zegz.jpg?ixlib=rb-1.1.0&rect=65%2C5%2C3928%2C2646&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cargo ships wait at the entrance to the Panama Canal in late September.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/cargo-ships-wait-at-the-entrance-of-the-panama-canal-at-news-photo/1687928473">Luis Acosta/AFP via Getty Images</a></span></figcaption></figure><p>Reports of <a href="https://www.nytimes.com/2023/11/01/business/economy/panama-canal-drought-shipping.html">lengthy shipping delays</a> for vessels traveling through the Panama Canal this year have highlighted the critical but often overlooked role that fresh water plays across global supply chains. Drier than normal conditions in Panama, brought on by El Niño, have <a href="https://www.bbc.com/news/business-67281776">left the region drought-stricken</a> and water levels in the locks that feed the canal lower than normal. This has led to fewer ships being able to pass through the canal each day: only <a href="https://apnews.com/article/panama-canal-locks-reduction-31-ships-061ce1797cb9b0fb8ea7ab44ba04bdf1.html">31 ships</a> currently, compared with 36 to 38 under normal conditions. This means longer waits to move products through the canal and onto store shelves. </p>
<p>The slowdown at the Panama Canal shows how access to fresh water is key to the way goods are made and shipped, <a href="https://www.cnn.com/2023/08/26/economy/panama-canal-supply-chain/index.html">affecting everything</a> from the price of groceries to retail forecasts for the upcoming holiday shopping season. As a <a href="https://harbert.auburn.edu/directory/dustin-cole.html">professor of supply chain management</a>, I think businesses would be wise to pay closer attention to this issue.</p>
<p>But first, you might ask: What does fresh water have to do with ocean freight? Plenty, it turns out.</p>
<h2>Water, water everywhere, and not enough to share</h2>
<p>The Panama Canal is a freshwater connection between two oceans – not a saltwater link, as one might assume. A series of locks on each side of the canal raise cargo freighters nearly 100 feet to human-made lakes that extend across Panama’s isthmus and lower them down to sea level on the other side. </p>
<p>Each crossing by a ship requires <a href="https://1997-2001.state.gov/regions/wha/panama/991206_faqs.html">52 million gallons</a> of fresh water from lakes, rivers and streams across this small country. This creates a trade-off between preserving water for local needs and using it to allow ships to traverse the canal. Less water allocated to the canal means fewer ships can pass through.</p>
<p>This isn’t an isolated phenomenon. Periodic low water levels in the <a href="https://www.wsj.com/articles/mississippi-river-careens-from-floods-to-low-water-threatening-barge-traffic-a6d5758d">Mississippi River</a> and the <a href="https://www.reuters.com/business/low-water-hampers-rhine-river-shipping-germany-2023-06-19/">Rhine River</a> in Germany have impeded barge traffic for years, disrupting supply chains while stoking debate about how to divide limited amounts of fresh water. Recent plans by communities in northern Colorado to <a href="https://insideclimatenews.org/news/10092023/colorado-river-upstream-use-it-before-they-lose-it-2/">build their own reservoirs</a> on tributaries of the Colorado River highlight questions about who owns access to local waterways and how this resource is governed.</p>
<h2>An ancient challenge</h2>
<p>The need to manage water resources isn’t new, with complex water management systems <a href="https://education.nationalgeographic.org/resource/roman-aqueducts/">dating back to the Roman Empire</a> and <a href="https://eal.isas.illinois.edu/projects/ancient-water-management/">even earlier</a>. Humankind has made great progress on water management over the centuries, but in recent years the issue has often taken a back seat to other pressing environmental concerns such as global warming. </p>
<p>Water management is complicated by the fact that businesses and communities sometimes find themselves in conflict: Businesses want to use water for their operations, while communities want to preserve water supplies to ensure that residents’ basic needs are met. At the same time, communities also need the jobs and services that businesses provide. Examples such as the Panama Canal highlight this tension.</p>
<p>Balancing these seemingly contrary needs calls for a deeper look into how much water is used in the making of products people buy and use every day.</p>
<p>As my colleagues and I show in a recent journal article, <a href="https://doi.org/10.1111/poms.13923">water is an important component</a> of almost everything people buy. For example, roughly <a href="https://interestingengineering.com/science/industrial-activity-is-draining-the-world-of-fresh-water">2,600 gallons of water</a> goes into making the fabric for a single pair of jeans. From growing cotton for the fibers needed to manufacturing the denim and getting those jeans onto shelves at The Gap, more and more water is embedded into each pair as it moves through the supply chain. </p>
<p>Essentially, businesses use water to transport water embedded in virtually all products they sell. This is why businesses have more than purely altruistic reasons to address water-related problems: It isn’t just good for society but also their own operations. A lack of water can hamper production and disrupt the supply chains that businesses rely on.</p>
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<figcaption><span class="caption">Inside the world’s largest cargo shipping bottleneck. | WSJ.</span></figcaption>
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<h2>Solutions for businesses</h2>
<p>There are a number of ways in which businesses can improve their water management to reduce their own consumption – and costs – while limiting their exposure to water risks.</p>
<p>First, companies should realize that not everything requires clean water. Wastewater from one process can be used for another that doesn’t require clean water. Similarly, not every process pollutes water, so reuse is easy for wastewater resulting from those processes, such as water used for cooling.</p>
<p>Second, firms can share wastewater between facilities for reuse, a concept called <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/industrial-ecology#">industrial ecology</a>. For example, nutrient-rich water from food production can be used for farm irrigation rather than being discharged.</p>
<p>And third, since water is an excellent medium for heat transfer, rather than trying to cool one area and heat another, companies can connect the systems. For example, global aluminum giant Novelis is deploying hot water used in the casting process at one of its plants in Europe to <a href="https://www.novelis.com/district-heating-with-casting-water/">heat a neighboring building</a>.</p>
<p>Opportunities abound for improving management of fresh water – one of our most precious resources. While stronger government regulations and expanded reporting requirements will help, decisions by businesses themselves can move that needle even more.</p>
<p>For those who do, their standing in the communities in which they operate will surely benefit – as will their bottom lines.</p><img src="https://counter.theconversation.com/content/216253/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dustin Cole does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Smart water management isn’t just good for the earth. It’s good for business.Dustin Cole, Assistant Professor of Supply Chain Management, Auburn UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2126902023-11-02T19:12:25Z2023-11-02T19:12:25ZTaming wild northern rivers could harm marine fisheries and threaten endangered sawfish<figure><img src="https://images.theconversation.com/files/556797/original/file-20231031-23-pl3bb0.JPG?ixlib=rb-1.1.0&rect=26%2C0%2C2198%2C1504&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Google Earth Image Landsat/Copernicus</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>Australia’s tropical northern rivers still run wild and free. These relatively pristine areas have so far avoided extensive development. But this might not last. There are <a href="https://www.dcceew.gov.au/water/policy/national/northern-australia">ongoing scoping studies exploring irrigating agricultural land</a> using water from these rivers.</p>
<p>Our <a href="https://www.nature.com/articles/s41893-023-01238-x">new research</a> in the journal Nature Sustainability shows disturbing the delicate water balance upstream can have major consequences downstream, even hundreds of kilometres away.</p>
<p>Using our latest computer modelling, we found northern water resource development would have substantial effects on prawn, mud crab and barramundi fisheries in the Gulf of Carpentaria. These are valuable Australian marine fisheries which depend on healthy estuaries. Reducing river flows would also disturb mangrove and seagrass habitats and threaten the iconic endangered largetooth sawfish.</p>
<p>Freshwater flows to the sea play a crucial role, boosting the productivity of marine, estuarine and freshwater systems. These complex interactions must be carefully considered in the assessment of future development plans.</p>
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<a href="https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphic illustrating how altering river flow influences downstream estuarine and marine species and habitats" src="https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/556412/original/file-20231029-25-tiz5y6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Changing the natural river flow regime has consequences for estuarine and marine species and fisheries.</span>
<span class="attribution"><span class="source">James Chen in Plaganyi et al (2023) Nature Sustainability</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
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Read more:
<a href="https://theconversation.com/if-we-protect-mangroves-we-protect-our-fisheries-our-towns-and-ourselves-214390">If we protect mangroves, we protect our fisheries, our towns and ourselves</a>
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<h2>Rivers are our lifeblood</h2>
<p>Worldwide, few wild running rivers remain. Their future is uncertain given <a href="https://turningthetide.watercommission.org/">growing demand for water</a>. </p>
<p>Climate change is putting extra pressure on rivers as temperatures rise, rainfall patterns shift and <a href="https://theconversation.com/marine-heatwaves-are-getting-hotter-lasting-longer-and-doing-more-damage-95637">extreme events</a> become more frequent. </p>
<p>Rivers are the lifeblood of ecosystems and communities. They connect land, estuaries and the sea. But assessments of river developments <a href="https://www.science.org/doi/epdf/10.1126/science.abj4017">often focus narrowly on local effects</a>. They ignore the fact downstream estuaries and marine systems depend on freshwater flows. Few studies have calculated the costs of upstream catchment developments to downstream estuarine and marine ecosystems and fisheries.</p>
<p>We must avoid the <a href="https://theconversation.com/damming-northern-australia-we-need-to-learn-hard-lessons-from-the-south-53885">mistakes made in southern Australia</a> where <a href="https://theconversation.com/excessive-water-extractions-not-climate-change-are-most-to-blame-for-the-darling-river-drying-192621">too much water has been taken out of the system</a> for growing crops. That means carefully evaluating the design of dams or irrigation schemes, considering when, where and how much water should be taken – and the likely trade-offs. </p>
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<a href="https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Photo showing many common banana prawns on a trawler. This is one of several species caught by the Northern Prawn Fishery" src="https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/556413/original/file-20231029-25-u36qo0.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Yields of common banana prawn vary depending on river flows from multiple catchments.</span>
<span class="attribution"><span class="source">NPF Industry Pty Ltd, Australian Council of Prawn Fisheries Ltd, Austral Fisheries and Raptis Seafoods</span></span>
</figcaption>
</figure>
<h2>Why should we care about northern rivers?</h2>
<p>Australia’s remote northern rivers are one of the last strongholds for endangered species such as the <a href="https://theconversation.com/australian-endangered-species-largetooth-sawfish-24558">largetooth sawfish</a>. These iconic species are born in estuaries before spending their first few years of life upstream in freshwater rivers. </p>
<p>Flows from these rivers also sustain extensive mangrove forests and seagrass beds. Periodic floods <a href="https://www.abc.net.au/news/2020-10-30/barramundi-banana-prawns-could-be-threatened-gulf-of-carpentaria/12828280">boost the food supply</a> for many prized marine fisheries such as prawns, barramundi and <a href="https://tinyurl.com/2haudz3t">mud crabs</a>.</p>
<p>The rivers also have <a href="https://indigenousknowledge.unimelb.edu.au/curriculum/resources/indigenous-voices-in-water">cultural significance</a> for Aboriginal people and represent a valuable resource, providing food and supporting livelihoods. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo of an endangered largetooth sawfish in shallow water" src="https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/556411/original/file-20231029-27-eror37.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Endangered largetooth sawfish are sensitive to changes in river flows.</span>
<span class="attribution"><span class="source">Rich Pillans/CSIRO</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/an-el-nino-hit-this-banana-prawn-fishery-hard-heres-what-we-can-learn-from-their-experience-139852">An El Niño hit this banana prawn fishery hard. Here’s what we can learn from their experience</a>
</strong>
</em>
</p>
<hr>
<h2>Using modelling to connect rivers, estuaries and oceans</h2>
<p>We coupled CSIRO’s sophisticated <a href="https://www.csiro.au/en/showcase/nawra">river models</a> with our <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/j.1467-2979.2012.00488.x">specially tailored ecosystem models</a> to represent how altering river flows may influence the downstream ecology and fishery yields. </p>
<p>We used catch data from fisheries to analyse how past natural changes in flow influenced catch rates. This was combined with extensive previous research on the biology and ecology of each species to model the dynamics of catchment-to-coast systems. We were particularly interested in the natural life cycles of fish and crustaceans in our unique northern wet-dry tropical rivers and estuaries. We then simulated multiple water resource development scenarios to assess and compare various impacts and ways to reduce them. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two column charts showing risk to key populations and fisheries in the Gulf of Carpentaria from changes in freshwater flows." src="https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=562&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=562&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=562&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=707&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=707&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547140/original/file-20230908-15-efu6e7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=707&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">We quantified risk to key populations and fisheries in the Gulf of Carpentaria from changes in freshwater flows due to various hypothetical water resource developments (WRD).</span>
<span class="attribution"><span class="source">Plagányi et al. (2023) Nature Sustainability</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>For <a href="https://tinyurl.com/2haudz3t">mud crabs, we linked river flow</a> and other climate drivers to their life cycle and were able to show how past changes in flow could explain the past variation in crab catch, particularly for rivers in which flow was seasonally variable. We could then use this model to predict how crab catch and abundance might change in the future, depending on how much water is removed from rivers and the method of removal.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Aerial image of an estuary feeding into the Gulf of Carpentaria" src="https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/546574/original/file-20230906-27-vx8vj3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Rivers connect land, estuaries and the sea. Large estuaries feed into the Gulf of Carpentaria.</span>
<span class="attribution"><span class="source">Queensland Department of Agriculture and Fisheries</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/as-industry-lines-up-to-take-water-from-a-wild-top-end-river-trees-tell-the-story-of-a-much-drier-past-177221">As industry lines up to take water from a wild Top End river, trees tell the story of a much drier past</a>
</strong>
</em>
</p>
<hr>
<h2>Integrated management from catchment to coast</h2>
<p>Our research shows freshwater flows to the sea are crucial for environmentally and economically important species. Any plan to dam or extract freshwater from Australia’s last wild rivers should account for these effects.</p>
<p>Coupling scientific knowledge about marine and freshwater ecosystems with catchment development will improve infrastructure planning and flow management.</p>
<p>This is vital on a dry continent already <a href="https://theconversation.com/extreme-weather-caused-by-climate-change-has-damaged-45-of-australias-coastal-habitat-120671">challenged by climate change</a>. Every drop counts.</p>
<p><em>The authors wish to acknowledge Annie Jarrett, Chief Executive Officer of NPF Industry Pty Ltd, which represents Northern Prawn Fishery operators, for her contribution to the research.</em></p><img src="https://counter.theconversation.com/content/212690/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Éva Plagányi acknowledges Annie Jarrett, Chief Executive Officer of NPF Industry Pty Ltd, which represents Northern Prawn Fishery operators, for her contribution to the research.
Éva works for CSIRO and receives research funding from several sources, including the Fisheries Research and Development Corporation (FRDC) and the Australian Fisheries Management Authority (AFMA).
2018-079 Ecological modelling of the impacts of water development in the Gulf of Carpentaria with particular reference to impacts on the NPF was supported by funding from the Fisheries Research and Development Corporation on behalf of the Australian Government</span></em></p><p class="fine-print"><em><span>Laura Blamey works for CSIRO, which receives research funding from several source, including the Fisheries Research and Development Corporation (FRDC) and the Australian Fisheries Management Authority (AFMA).</span></em></p><p class="fine-print"><em><span>Michele Burford works for the Australian Rivers Institute, Griffith University and receives funding from several sources, including the National Environmental Science Program (NESP).</span></em></p><p class="fine-print"><em><span>Robert Kenyon works CSIRO, an organisation that receives research funding from several sources, including the Fisheries Research and Development Corporation (FRDC) and the Australian Fisheries Management Authority (AFMA).</span></em></p>Any plan to dam or extract water from some of Australia’s last wild rivers must carefully consider the consequences. Prawn, mud crab and barramundi fisheries could suffer in the Gulf of Carpentaria.Éva Plagányi, Senior Principal Research Scientist, CSIROLaura Blamey, Senior Research Scientist, CSIROMichele Burford, Professor - Australian Rivers Institute, and Dean - Research Infrastructure, Griffith UniversityRobert Kenyon, Marine Ecologist, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2146202023-10-11T12:30:46Z2023-10-11T12:30:46ZWhat is seawater intrusion? A hydrogeologist explains the shifting balance between fresh and salt water at the coast<figure><img src="https://images.theconversation.com/files/552819/original/file-20231009-22-uvy78h.jpg?ixlib=rb-1.1.0&rect=18%2C12%2C4031%2C2683&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In 2022, California built an emergency drought barrier across the West False River near Oakley to protect against saltwater intrusion. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/FreshwaterLosingBattleAgainstOcean/0b33666dca68482bb6d393fcf1d0ebdb/photo">AP Photo/Terry Chea</a></span></figcaption></figure><p>Seawater intrusion is the movement of saline water from the ocean or estuaries into freshwater systems. The seawater that has <a href="https://www.whitehouse.gov/briefing-room/presidential-actions/2023/09/27/president-joseph-r-biden-jr-approves-louisiana-emergency-declaration-4/">crept up the Mississippi River</a> in the summer and early fall of 2023 is a reminder that coastal communities teeter in a fragile land-sea balance. </p>
<p>Fresh water is essential for drinking, irrigation and healthy ecosystems. When seawater moves inland, the salt it contains can wreak havoc on farmlands, ecosystems, lives and livelihoods. </p>
<p>I am a <a href="https://scholar.google.com/scholar?hl=en&as_sdt=0,8&q=holly+michael&oq=holly">coastal hydrogeologist</a> and have studied water across the land-sea interface for 25 years. I think of seawater intrusion as being like a seesaw: The place where fresh water and salt water meet is the balance point between forces from land and forces from the sea. </p>
<p>A push from the land side, such as heavy rainfall or high river flows, moves the balance point seaward. A push from the sea side – whether it’s sea-level rise, storm surge or high tides – moves the balance point landward. Droughts or heavy use of fresh water can also cause seawater to move inland. As climate change and population growth stress freshwater supplies, one result will be <a href="https://www.epa.gov/climateimpacts/climate-change-impacts-freshwater-resources">more seawater intrusion</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552820/original/file-20231009-17-7xa2ak.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graphic of a coastal aquifer." src="https://images.theconversation.com/files/552820/original/file-20231009-17-7xa2ak.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552820/original/file-20231009-17-7xa2ak.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552820/original/file-20231009-17-7xa2ak.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552820/original/file-20231009-17-7xa2ak.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552820/original/file-20231009-17-7xa2ak.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552820/original/file-20231009-17-7xa2ak.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552820/original/file-20231009-17-7xa2ak.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Under natural conditions, fresh water flows underground toward the ocean and keeps seawater from moving into coastal aquifers. Pumping too much groundwater from the aquifer lowers water levels and can draw seawater inland.</span>
<span class="attribution"><a class="source" href="https://ca.water.usgs.gov/sustainable-groundwater-management/seawater-intrusion-california.html">USGS</a></span>
</figcaption>
</figure>
<h2>When the ocean moves upriver</h2>
<p>The current seawater intrusion in the lower Mississippi River is due primarily to <a href="https://www.washingtonpost.com/climate-environment/2023/09/29/saltwater-intrusion-louisiana-drinking-water/">drought in the Midwest</a>, which has reduced the river’s volume. Both the magnitude of reduction in river flow and the length of time that the river is low influence how far upriver the salt water moves. As of Oct. 2, 2023, the saltwater “wedge” in the Mississippi had moved <a href="https://www.mvn.usace.army.mil/Missions/Engineering/Stage-and-Hydrologic-Data/SaltwaterWedge/SaltwaterWedgeNow/">nearly 70 miles upstream</a> from the river’s mouth.</p>
<p>This <a href="https://theconversation.com/record-low-water-levels-on-the-mississippi-river-in-2022-show-how-climate-change-is-altering-large-rivers-193920">isn’t the first time</a> that low water on the river has allowed seawater to move inland. But as climate change raises sea levels and causes more severe weather anomalies, intrusion will become more common and will inch farther upstream. </p>
<p>And the problem isn’t unique to the Mississippi. In Delaware, seawater is <a href="https://doi.org/10.1111/gwat.13274">traveling farther up small tidal streams</a> during storms and the highest tides, flooding farmland and killing crops. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/t9papp-5QCo?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Researchers in Maryland explain how seawater intrusion threatens coastal agriculture.</span></figcaption>
</figure>
<p>In the Sundarbans of India and Bangladesh – one of the largest coastal mangrove forests in the world – seawater is intruding into the mouth of the Ganges River. The main causes there are upstream dams and water diversions from the river for irrigation and navigability, plus encroachment due to sea-level rise. Seawater intrusion could <a href="https://doi.org/10.1007/s00027-006-0868-8">threaten many types of plants and animals</a> in this <a href="https://whc.unesco.org/en/list/798/">UNESCO World Heritage Site</a>, which is home to countless rare and endangered species. </p>
<h2>Invading underground</h2>
<p>Another interface between fresh water and salt water at the coast is less obvious because <a href="https://www.usgs.gov/mission-areas/water-resources/science/saltwater-intrusion">it’s underground</a>. Many coastal communities draw their freshwater supply from groundwater – clean water that moves through pore spaces between grains of sand and soil. </p>
<p>Groundwater doesn’t just stop at the coastline: Under the ocean floor, the groundwater is salty, and somewhere between land and the ocean, there is an underground meeting point. It typically is landward of the coastline because salt water is denser than fresh water, so it has a greater force and naturally pushes in. But just as with a river, <a href="https://www.usgs.gov/mission-areas/water-resources/science/saltwater-intrusion">that interface moves</a> when groundwater levels drop on land or water levels rise offshore. </p>
<p>In <a href="https://data.cnra.ca.gov/dataset/ca-gw-basin-boundary-descriptions">groundwater basins</a> of central and southern California, <a href="https://theconversation.com/drilling-deeper-wells-is-a-band-aid-solution-to-us-groundwater-woes-121219">widespread pumping</a> has caused groundwater levels to drop hundreds of feet in some areas. This is tipping the seesaw and causing groundwater from the sea to move far inland. Accessible groundwater has supported irrigated agriculture in these areas, but now the double hazard of reduced groundwater availability and seawater intrusion <a href="https://www.climatehubs.usda.gov/hubs/california/topic/climate-vulnerabilities-california-specialty-crops">threatens crops like strawberries and lettuce</a>.</p>
<p>Seawater intrusion into groundwater is happening all over the world, but perhaps the most threatened places are communities on <a href="https://www.nature.com/articles/nclimate3128">low-lying islands</a>. Fresh groundwater is often the sole source of water for drinking and irrigation on small islands, and it exists in a thin lens that floats on top of saline groundwater. </p>
<p>The lens can shrink in response to droughts, pumping and sea-level rise. It can also become salty from floodwater infiltration during storms or high tides. </p>
<p>In the Marshall Islands, for example, a combination of sea-level rise and wave-driven flooding is predicted to make many islands <a href="http://dx.doi.org/10.1126/sciadv.aap9741">uninhabitable by the end of the century</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/552822/original/file-20231009-17-622g49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A woman pours water from a box into her dog's dish" src="https://images.theconversation.com/files/552822/original/file-20231009-17-622g49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/552822/original/file-20231009-17-622g49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/552822/original/file-20231009-17-622g49.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/552822/original/file-20231009-17-622g49.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/552822/original/file-20231009-17-622g49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/552822/original/file-20231009-17-622g49.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/552822/original/file-20231009-17-622g49.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Kelli Marinovich fills her dog’s bowl with boxed water at her home in Buras, La., on Oct. 4, 2023. With salt water moving up the Mississippi River, thousands of Plaquemines Parish residents have been living on bottled water and dealing with saltwater intrusion for more than three months.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/kelli-marinovich-fills-her-dogs-bowl-with-boxed-water-at-news-photo/1712281174">Kathleen Flynn/Washington Post via Getty Images</a></span>
</figcaption>
</figure>
<h2>Shifting the balance</h2>
<p>As salt water continues to encroach on freshwater systems, there will be consequences. Drinking water that contains even 2% seawater can <a href="https://www.cnn.com/2023/10/05/health/louisiana-salt-levels-drinking-water-health/index.html">increase blood pressure and stress kidneys</a>. If salt water gets into supply lines, it can <a href="https://doi.org/10.1016/j.jenvman.2022.115153">corrode pipes</a> and produce <a href="https://doi.org/10.1016/j.desal.2014.04.021">toxic disinfection by-products</a> in water treatment plants. </p>
<p>Seawater intrusion reduces the life span of roads, bridges and other infrastructure. It has been implicated as a contributor to the <a href="https://www.nbcnews.com/news/us-news/surfside-condo-collapse-salt-groundwater-rcna16473">Champlain Towers South condominium collapse</a> in Surfside, Florida, in 2021. Seawater intrusion changes ecosystems, creating <a href="https://doi.org/10.1073/pnas.2314607120">ghost forests</a> as trees die and marshes move inland.</p>
<p><a href="https://doi.org/10.1002/2017WR020851">Smart management</a> can tip the seesaw back toward the sea. Limiting surface water extraction and groundwater pumping, or injecting treated wastewater into vulnerable aquifers, can increase the force pushing against intruding salt water. </p>
<p>Constructing <a href="https://oceanservice.noaa.gov/facts/shoreline-armoring.html">seawalls</a> or maintaining <a href="https://coastalscience.noaa.gov/news/understanding-processes-driving-sand-dune-erosion-and-creation-on-an-atlantic-seashore/">healthy dune systems</a> also can help hold seawater at bay, though these approaches protect only against saltwater flooding and infiltration at the surface, not underground. Pumping out saline groundwater or installing underground barriers can keep deeper salt water from moving inland. </p>
<p>Being proactive is best, because once groundwater is contaminated, it’s hard to remove the salt. If salt water does penetrate inland, communities can manage water quality by constructing <a href="https://www.usgs.gov/special-topics/water-science-school/science/desalination">desalination plants</a> and switching to salt-tolerant crops. </p>
<p>Another option is to let nature take its course. Allowing marshes to migrate inland can <a href="https://doi.org/10.1002/2016GL068507">compensate for losses at the coastline</a> as sea level rises. This preserves critical habitats, enhances flood protection and stores carbon at rates <a href="https://oceanservice.noaa.gov/ecosystems/coastal-blue-carbon/">far exceeding most terrestrial ecosystems</a> – dialing back the acceleration of climate change.</p><img src="https://counter.theconversation.com/content/214620/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Holly Michael receives funding from the US National Science Foundation, the US Geological Survey, and the US National Park Service.</span></em></p>Saltwater intrusion is bad for human health, ecosystems, crops and infrastructure. Here’s how seawater can move inland, and why climate change is making this phenomenon more frequent and severe.Holly Michael, Director, Delaware Environmental Institute, and Professor of Earth Sciences and Civil and Environmental Engineering, University of DelawareLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2131202023-09-21T22:07:48Z2023-09-21T22:07:48ZHow the Peach Blossom Jellyfish is spreading across North America<figure><img src="https://images.theconversation.com/files/548221/original/file-20230914-17-v07w3f.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4000%2C3000&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Peach Blossom Jellyfish (Craspedacusta sowerbii) is native to China and an invasive species in Canada.</span> <span class="attribution"><span class="source">(Florian Lüskow)</span>, <span class="license">Author provided</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/how-the-peach-blossom-jellyfish-is-spreading-across-north-america" width="100%" height="400"></iframe>
<p>Invasive species <a href="https://www.canada.ca/en/environment-climate-change/services/biodiversity/invasive-alien-species-strategy.html">are a real problem in Canada</a>, and one species in particular, the freshwater jellyfish species of the genus <em>Craspedacusta sowerbii</em> — <em>C. sowerbii</em>, or the Peach Blossom Jellyfish — are as widespread as they are also poorly understood. </p>
<p>There is anecdotal evidence that the invasive jellyfish had been present in British Columbia lakes and ponds for decades. Still, compiled data suggest that the number of sightings has increased considerably since the year 2000. </p>
<p>Unfortunately, however, we still have very limited information about the range of its presence in Canada, how it got here, how it spreads and what its essential impact on freshwater ecosystems across Canada may be. No mitigation and management strategy has yet been developed and many fundamental questions about the species ecology are unanswered.</p>
<h2>Climate change and species introductions</h2>
<p>The <em>Craspedacusta</em> species is a subtropical but adaptable organism which favours moderate- to high-water temperatures. While cold water temperatures have acted as a historical check on their growth and expansion, warming temperatures around the globe are helping to expand their territory.</p>
<p>Recent increases in sightings of <em>C. sowerbii</em> in B.C., across Canada and worldwide are therefore indicative of an expanding suitable habitat for the jellyfish as a result of global warming, alongside a <a href="https://www.int-res.com/articles/ab2021/30/b030p069.pdf">growing public awareness and increased observational efforts</a> leading to more effective recognition.</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/invasive-species-cause-billions-of-dollars-in-damage-worldwide-4-essential-reads-212924">Invasive species cause billions of dollars in damage worldwide: 4 essential reads</a>
</strong>
</em>
</p>
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<p>Current modelling shows that the Peach Blossom Jellyfish will expand to ever higher latitudes in both hemispheres over this century and be <a href="https://doi.org/10.3354/ab00742">present in freshwater systems longer in the year from spring to late autumn</a>. </p>
<p>Unfortunately, the species has rarely been the focus of research. Currently, as far as I am aware, only biological oceanographer Evgeny Pakhomov and I are now researching the species and its significance for Canada.</p>
<p>Our research shows that this trend is not restricted to B.C., but is expected to happen in other provinces such as Alberta, Ontario and Québec too. <em>Craspedacusta sowerbii</em> irregularly occurs in the Great Lakes area on both sides of the Canada-United States border since the 1930s.</p>
<h2>Small invader, unpredictable occurrence</h2>
<p>The current state of provincial monitoring and reporting on this species is, unfortunately, lacklustre. </p>
<p>While a number of tools and data have been shown to be effective <a href="https://doi.org/10.1002/rra.3947">in monitoring populations in North America and Europe</a>, no province currently includes these in annual reports and statistics. </p>
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Read more:
<a href="https://theconversation.com/a-battlefield-for-ants-new-study-on-ant-warfare-shows-we-could-manipulate-their-fights-211127">A battlefield for ants? New study on ant warfare shows we could manipulate their fights</a>
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<p>For example, the <a href="https://bcinvasives.ca/">Invasive Species Council of British Columbia’s annual report</a> does not cunduct large-scale data synthesis on the Peach Blossom Jellyfish. As a result of this lack of data, no evidence of seasonal or long-term population trends exists.</p>
<p>Compounding these difficulties is the fact that the <em>C. sowerbii</em> is known as a species complex, meaning that there are likely several species going undetected under the same name. The nuances of these species distinctions are not only of academic interest, but also hold the key to identifying how these species move across and between ecosystems.</p>
<p>Understanding all of these aspects is crucial for us to start seriously thinking about mitigation and management strategies.</p>
<h2>We cannot manage what we don’t understand</h2>
<p>While the species is harmless to humans, it is unknown how the freshwater jellyfish interact with other lake and pond inhabitants. There is evidence that these jellyfish are a potentially rich source of food for juvenile fish and they could <a href="https://doi.org/10.3390/biology12060814">compete with other native species as food</a>.</p>
<p>Meanwhile, not enough up-to-date information is available about the various life stages of the jellyfish and the particular impacts of each stage. Indeed, <a href="https://doi.org/10.3390/biology11081100">while polyps and other juvenile stages are present year-round</a>, their exact locations, abundance and activity levels are entirely unknown.</p>
<p>While governmental reporting infrastructure does exist in some provinces and territories, large-scale data have not yet been analyzed. Efforts are hampered by the lack of inclusion of the Peach Blossom Jellyfish in regular monitoring programs. </p>
<p>We hope to stimulate interest and motivation to better understand this problem at all levels from federal to provincial governments and local municipalities.</p>
<p>This lack of data, and effort by provinces to collect them, has serious consequences for Canada’s ecological security and limits the effectiveness of any management or adaptation plan in the years to come.</p><img src="https://counter.theconversation.com/content/213120/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Florian Lüskow does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The Peach Blossom Jellyfish is an invasive species in Canada, and a lack of data is hampering efforts to control populations.Florian Lüskow, Postdoctoral research fellow, Faculty of Science, University of British ColumbiaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2137622023-09-19T04:31:41Z2023-09-19T04:31:41ZWhat are ‘planetary boundaries’ and why should we care?<figure><img src="https://images.theconversation.com/files/548985/original/file-20230919-15-6o2a50.jpg?ixlib=rb-1.1.0&rect=844%2C5%2C2736%2C1976&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/nasa-captures-epic-earth-image">NASA</a></span></figcaption></figure><p>As far as we know, there is exactly one planet in our Solar System – and the galaxy – which hosts life. And you’re on it. </p>
<p>For the first 800 million years, Earth was dead. Then life began making itself at home. For over three billion years, lifeforms have helped shape their own environment. Earth’s energy balance (commonly known as the climate) and its interactions with trillions of species is the main determinant of environmental conditions. </p>
<p>As you know, one species – ours – is exceptionally good at changing our environment to suit us. The problem is, we’re now too good at it. We chop down forests, remove mountains to get at ore bodies, take over grassland, fish out entire seas, create and unleash novel chemicals and pump huge quantities of nutrients from fertiliser into the system. These and many more undermine the hidden life support system on which we rely. </p>
<h2>What are planetary boundaries?</h2>
<p>Almost 15 years ago, this article’s lead author helped create something called “planetary boundaries” to make clear what damage we had done. </p>
<p>We teased apart nine processes vital to the Earth system. </p>
<p>Three are based on what we take from the system: </p>
<ul>
<li>biodiversity loss</li>
<li>fresh water</li>
<li>land use. </li>
</ul>
<p>The remaining six come from waste we deposit back into the environment: </p>
<ul>
<li>greenhouse gases (which cause climate change and ocean acidification)</li>
<li>ozone-depleting chemicals</li>
<li>novel entities (plastic, concrete, synthetic chemicals and genetically modified organisms which owe their existence to us)</li>
<li>aerosols</li>
<li>nutrient overload (reactive nitrogen and phosphorus from fertilisers)</li>
</ul>
<p>If we keep our activities to a safe level, the sheer exuberance of life and the planet’s own processes can handle it. But in six out of nine vital life support systems, we have blown <a href="https://www.science.org/doi/10.1126/sciadv.adh2458">well past</a> the safe zone. And we’re now in the danger zone, where we – as well as every other species – are now at risk. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/548987/original/file-20230919-21-izom3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="planetary boundaries update 2023" src="https://images.theconversation.com/files/548987/original/file-20230919-21-izom3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548987/original/file-20230919-21-izom3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=567&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548987/original/file-20230919-21-izom3a.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=567&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548987/original/file-20230919-21-izom3a.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=567&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548987/original/file-20230919-21-izom3a.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=712&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548987/original/file-20230919-21-izom3a.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=712&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548987/original/file-20230919-21-izom3a.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=712&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Here’s the sum total of our impact on the planet. You can see the areas we’re still within safe limits – and those where we are well past.</span>
<span class="attribution"><span class="source">Azote for Stockholm Resilience Centre based on analysis in Richardson et al 2023</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Our breach of boundaries is very new</h2>
<p>In the year 1900, there were around 1.6 billion humans – nearly all of them poor. Now there are 8 billion of us, and some of them are rich. And nearly all of us use fossil fuels, plastics, chemicals and products from intensive agriculture. </p>
<p>It can be very easy to live our lives and only occasionally glimpse the reality. You might have flown over palm oil plantations where rainforest was. Seen blue-green algal blooms or fish kills. You might have wondered where all the animals or bugs were on a bushwalk. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/humanity-is-in-the-existential-danger-zone-study-confirms-36307">Humanity is in the existential danger zone, study confirms</a>
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</em>
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<hr>
<p>But when we zoom out and look at the sum total of our impacts, the story is clear. Put bluntly, we are eating away at our own life support systems. And this has happened extraordinarily recently. If we keep going, we risk triggering a dramatic and potentially irreversible change in living conditions. </p>
<p>Like all other living organisms, we survive by using Earth’s resources. We once believed these resources were unlimited. But we now know there are hard limits. </p>
<p>Take fresh water – essential to life on land. If we pump too much water from rivers, lakes and aquifers for farming, industry or cities, we risk hitting that hard limit. This isn’t hypothetical – places like <a href="https://www.nytimes.com/2023/09/01/climate/india-groundwater-depletion.html">India</a> and <a href="https://www.nytimes.com/2023/08/30/us/california-groundwater-depletion.html">California</a> are close to that limit. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/548991/original/file-20230919-25-7cih0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="india groundwater" src="https://images.theconversation.com/files/548991/original/file-20230919-25-7cih0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548991/original/file-20230919-25-7cih0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=397&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548991/original/file-20230919-25-7cih0r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=397&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548991/original/file-20230919-25-7cih0r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=397&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548991/original/file-20230919-25-7cih0r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=499&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548991/original/file-20230919-25-7cih0r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=499&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548991/original/file-20230919-25-7cih0r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=499&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Unsustainable use of groundwater in many countries is likely to trigger freshwater crises.</span>
<span class="attribution"><span class="source">India groundwater</span></span>
</figcaption>
</figure>
<h2>How are these boundaries calculated?</h2>
<p>Remember – the entirety of human civilisation, the flowering of culture, religion, agriculture and cities – has taken place only in the last 10–12,000 years. For the roughly 190,000 years before that, we were nomadic hunter-gatherers. What changed? </p>
<p>The climate, for one. We entered a climate sweet spot, with relatively stable and warm conditions. Gone were the recurring ice ages. Many experts believe there’s a connection here – stable climate, rise of civilisation, though this is hard to establish with certainty. </p>
<p>What we do know is we can thrive under these conditions. We don’t know for certain our civilisation as we know it can thrive if they are different. We would be foolish to risk pushing our supporting envelope to breaking point. </p>
<p>That’s why we and many other independent scientists have worked as hard as we have to develop the framework of planetary boundaries and keep it up-to-date as new science comes in. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/its-not-just-climate-weve-already-breached-most-of-the-earths-limits-a-safer-fairer-future-means-treading-lightly-206678">It's not just climate – we've already breached most of the Earth's limits. A safer, fairer future means treading lightly</a>
</strong>
</em>
</p>
<hr>
<h2>How do we know if we’ve breached the boundaries?</h2>
<p>The Earth’s environmental conditions have changed many times in its long history. Climate is a good example here. We know the Earth looked very different when temperatures were higher or lower. Palms <a href="https://www.bbc.com/news/science-environment-19077439">once grew</a> in Antarctica. These swings from hothouse to ice age let us estimate the boundary beyond which our activities can upset the process. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/548990/original/file-20230919-25-4vmlhh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="palm trees snow background" src="https://images.theconversation.com/files/548990/original/file-20230919-25-4vmlhh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548990/original/file-20230919-25-4vmlhh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548990/original/file-20230919-25-4vmlhh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548990/original/file-20230919-25-4vmlhh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548990/original/file-20230919-25-4vmlhh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548990/original/file-20230919-25-4vmlhh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548990/original/file-20230919-25-4vmlhh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Palm trees once grew in an ice-free Antarctica.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>These are boundaries, not thresholds. When we cross one, it doesn’t trigger immediate disaster. And it’s entirely possible to bring our activities back from unsafe to safe. We’ve done it already in the 1990s, when international cooperation quickly phased out ozone-depleting chemicals and stopped the dangerous ozone hole from getting ever-bigger. </p>
<p>So how are we doing? Not great. </p>
<p>In last week’s <a href="https://www.science.org/doi/10.1126/sciadv.adh2458">update</a>, the research team found we had now gone beyond the safe zone into dangerous territory in six of the nine processes. We are still in the green for ozone-depleting chemicals. Ocean-acidification is still, just, in the green, and so is aerosol pollution and dust. </p>
<p>But on climate change, deforestation, biodiversity loss, synthetic chemicals such as plastics, freshwater depletion, and nitrogen/phosphorus use, we’re well out of the safer zone. On these six, we’re deep in the red zone.</p>
<p>We’re keeping the party going as long as possible. But it can’t continue indefinitely. The bill comes due. The faster we do for the other boundaries what we did for ozone-depleting chemicals, the safer all of us will be. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/two-trillion-tonnes-of-greenhouse-gases-25-billion-nukes-of-heat-are-we-pushing-earth-out-of-the-goldilocks-zone-202619">Two trillion tonnes of greenhouse gases, 25 billion nukes of heat: are we pushing Earth out of the Goldilocks zone?</a>
</strong>
</em>
</p>
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<img src="https://counter.theconversation.com/content/213762/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Xuemei Bai receives funding from the Australian government, Department of Industry, Science, Energy and Resources, the National Health and Medical Research Council (NHMRC), The Future Earth, and the Australian National University. She is affiliated with the Earth Commission.</span></em></p><p class="fine-print"><em><span>Katherine Richardson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>We’ve become so good at using the Earth’s resources we’re endangering the systems we rely on.Katherine Richardson, Professor in Biological Oceanography, University of CopenhagenXuemei Bai, Distinguished Professor, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2094872023-07-12T20:04:25Z2023-07-12T20:04:25Z‘Humanity’s signature’: study finds plastic pollution in the world’s lakes can be worse than in oceans<p>A world-first study has found concentrations of plastics in some lakes are higher than in the most contaminated parts of oceans, demonstrating the extent to which plastics have invaded Earth’s ecosystems.</p>
<p>In a study <a href="https://www.nature.com/articles/s41586-023-06168-4">released today</a>, researchers sampled 38 lakes and reservoirs around the world, including in Australia, the United States, United Kingdom and Europe. Plastics and microplastics were found at every site, including very remote locations.</p>
<p>Lakes are sentinels for human activity. Many lakes are already suffering from issues such as algal blooms, deoxygenation, over-extraction and drying. Plastic contamination adds yet another threat to these highly stressed ecosystems.</p>
<h2>The plastics problem</h2>
<p>After plastics enter the environment, they generally break up and become smaller and smaller. Eventually they become microplastics – defined as particles less than 5 mm in size. </p>
<p>Plastic takes decades to disappear. It can <a href="https://oceanservice.noaa.gov/facts/microplastics.html">harm</a> ocean and aquatic life and contaminate water used by humans. </p>
<p>Plastics can be washed into lakes from the adjacent land areas. Lake water can sit for a long time without being flushed out, allowing plastics to accumulate.
We don’t yet know much about whether microplastics are absorbed by filter feeding organisms such as clams, mussels and zooplankton, and how plastics affect the food chain.</p>
<p>Plastic debris is widespread in freshwater ecosystems. But much of the focus has been on marine ecosystems, and knowledge of the scope of the problem in lakes and reservoirs has been hampered by a lack of appropriate data. Our research set out to close this gap.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/plastic-pollution-threatens-birds-far-out-at-sea-new-research-209081">Plastic pollution threatens birds far out at sea – new research</a>
</strong>
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</p>
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<h2>What we did</h2>
<p>A global team of scientists, of which we were part, examined the abundance and type of plastic debris in freshwater ecosystems. Surface waters were sampled in 38 lakes and reservoirs across 23 countries (mostly in the Northern Hemisphere) and six continents.</p>
<p>Importantly, we used a standardised collection and analysis method, including very fine plankton nets to sample the plastic debris. These steps allowed for comparisons between lakes. </p>
<p>Broadly, we found plastic debris in all lakes studied. Most plastics were in the microplastic size range. However, concentrations varied widely. </p>
<p>Some 21 lakes had low concentrations – below one particle per cubic metre (m³). Of the remainder, 14 lakes had concentrations between one and five particles per m³ and three lakes had concentrations higher than five particles per m³.</p>
<p><a href="https://en.wikipedia.org/wiki/Forest_Lake,_Queensland">Forest Lake</a> in Brisbane was the Australian study site. It’s a popular urban lake used by many people for recreation. This lake had three plastics particles per cubic metre, ranking it sixth worst among the 38 lakes sampled. </p>
<p>The three most polluted lakes were, in order, Lake Lugano (Switzerland, Italy), Lake Maggiore (Italy) and Lake Tahoe (US). </p>
<p>In each of these lakes, plastic concentrations reached or exceeded those in “floating garbage patches” – marine areas collecting large amounts of debris, such as the <a href="https://education.nationalgeographic.org/resource/great-pacific-garbage-patch/">Great Pacific Garbage Patch</a>. These ocean areas were previously thought to be the worst cases of plastic pollution in water environments. </p>
<p>These three polluted lakes – as well as the heavily contaminated Lough Neagh in Northern Ireland – are also important sources of drinking water for local communities.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/whales-and-dolphins-found-in-the-great-pacific-garbage-patch-for-the-first-time-122538">Whales and dolphins found in the Great Pacific Garbage Patch for the first time</a>
</strong>
</em>
</p>
<hr>
<figure class="align-center ">
<img alt="hands sorting plastic debris" src="https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536750/original/file-20230711-17-y5zzsa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A crew sorting plastic debris collected from the Great Pacific Garbage Patch in 2019.</span>
<span class="attribution"><span class="source">The Ocean Cleanup</span></span>
</figcaption>
</figure>
<h2>Where is the plastic coming from?</h2>
<p>The second part of our study sought to identify the landscape factors affecting the abundance and type of plastic debris.</p>
<p>More than 90% of the plastic particles belonged to two shape categories: fibres and fragments. We even found textile fibres in lakes and reservoirs in remote areas with limited human presence, such as Avery Lake in the US state of Michigan.</p>
<p>Our analysis indicated two types of lake are particularly vulnerable to plastic contamination: those in highly urbanised and populated areas, and those with a large surface area.</p>
<p>The most common colour of plastic particle was black (30%), followed by transparent (24%), blue (18%) and white (13%). The low concentrations of particles in bright colours, such as red, suggests these more visible plastics may have been mistaken by aquatic organisms for food, and ingested.</p>
<h2>So what next?</h2>
<p>Marine environments are generally considered the final resting place for plastic debris. But our research confirms plastic concentrations in freshwater ecosystems can be higher than those in oceans. </p>
<p>Our results indicate that lakes play a major role in the global plastic cycle. This points to an urgent need to develop management policies to reduce plastic pollution in freshwater lakes. This, in turn, will help prevent plastics from entering waterways and ending up in marine systems.</p>
<p>We don’t know how much plastic debris ends up in water supplies. We suggest this gap be addressed as soon as possible, and the ecological harm caused by microplastics should become a global management and research priority.</p>
<p>Our study also underscores the urgent need for coordinated, systematic monitoring of plastic pollution.</p>
<p>Sadly, it seems no lake can be considered truly “pristine” with respect to plastic pollution. Our research serves as yet another unfortunate reminder of humanity’s indelible signature on nature. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-have-no-idea-how-much-microplastic-is-in-australias-soil-but-it-could-be-a-lot-96858">We have no idea how much microplastic is in Australia's soil (but it could be a lot)</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/209487/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Hamilton receives funding from the Australian Research Council.</span></em></p><p class="fine-print"><em><span>Deniz Özkundakci received funding from the Bay of Plenty Regional Council. He also holds the Toihuarewa Waimāori - Bay of Plenty Regional Council Chair in Lake and Freshwater Science
</span></em></p><p class="fine-print"><em><span>Mohammadhassan Ranjbar receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Justin Brookes does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Researchers even found textile fibres in very remote lakes with limited human presence.David Hamilton, Director, Australian Rivers Institute, Griffith UniversityDeniz Özkundakci, Associate Professor of Lake and Freshwater Science, University of WaikatoJustin Brookes, Director, Water Research Centre, University of AdelaideMohammad Hassan Ranjbar, Research Fellow, Griffith UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2066782023-05-31T20:07:56Z2023-05-31T20:07:56ZIt’s not just climate – we’ve already breached most of the Earth’s limits. A safer, fairer future means treading lightly<figure><img src="https://images.theconversation.com/files/529253/original/file-20230531-25-o2l9kr.jpg?ixlib=rb-1.1.0&rect=11%2C5%2C3776%2C2118&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>People once believed the planet could always accommodate us. That the resilience of the Earth system meant nature would always provide. But we now know this is not necessarily the case. As big as the world is, our impact is bigger. </p>
<p>In <a href="https://doi.org/10.1038/s41586-023-06083-8">research</a> released today, an international team of scientists from the <a href="https://earthcommission.org/">Earth Commission</a>, of which we were part, identified eight “safe” and “just” boundaries spanning five vital planetary systems: climate change, the biosphere, freshwater, nutrient use in fertilisers and air pollution. This is the first time an assessment of boundaries has quantified the harms to people from changes to the Earth system. </p>
<p>“Safe” means boundaries maintaining stability and resilience of our planetary systems on which we rely. “Just”, in this work, means boundaries which minimise significant harm to people. Together, they’re a health barometer for the planet. </p>
<p>Assessing our planet’s health is a big task. It took the expertise of 51 world-leading researchers from natural and social sciences. Our methods included modelling, literature reviews and expert judgement. We assessed factors such as tipping point risks, declines in Earth system functions, historical variability and effects on people.</p>
<p>Alarmingly, we found humanity has exceeded the safe and just limits for four of five systems. Aerosol pollution is the sole exception. Urgent action, based on the best available science, is now needed. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/529201/original/file-20230530-21-z6g13x.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/529201/original/file-20230530-21-z6g13x.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=364&fit=crop&dpr=1 600w, https://images.theconversation.com/files/529201/original/file-20230530-21-z6g13x.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=364&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/529201/original/file-20230530-21-z6g13x.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=364&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/529201/original/file-20230530-21-z6g13x.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=458&fit=crop&dpr=1 754w, https://images.theconversation.com/files/529201/original/file-20230530-21-z6g13x.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=458&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/529201/original/file-20230530-21-z6g13x.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=458&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This illustration shows how we’ve breached almost all the eight safe and just Earth system boundaries globally.</span>
<span class="attribution"><span class="source">Author provided</span></span>
</figcaption>
</figure>
<h2>So, what did we find?</h2>
<p>Our work builds on the influential concepts of <a href="https://www.science.org/doi/10.1126/science.1259855">planetary boundaries</a> by finding ways to quantify what <a href="https://www.nature.com/articles/s41893-023-01064-1">just systems</a> look like alongside safety. </p>
<p>Importantly, the safe and just boundaries are defined at local to global spatial scales appropriate for assessing and managing planetary systems – as small as one square kilometre in the case of biodiversity. This is crucial because many natural functions <a href="https://doi.org/10.1016/j.oneear.2022.11.013">act at local scales</a>. </p>
<p>Here are the boundaries: </p>
<p><strong>1. Climate boundary – keep warming to 1°C</strong></p>
<p>We know the <a href="https://unfccc.int/sites/default/files/english_paris_agreement.pdf">Paris Agreement goal</a> of 1.5°C avoids a <a href="https://doi.org/10.1126/science.abn7950">high risk</a> of triggering dangerous climate tipping points. </p>
<p>But even now, with warming at 1.2°C, many people around the world are being hit hard by climate-linked disasters, such as the recent extreme heat in China, fires in Canada, severe floods in Pakistan and droughts in the United States and the Horn of Africa. </p>
<p>At 1.5°C, <a href="https://www.nature.com/articles/s41893-023-01132-6">hundreds of millions of people</a> could be exposed to average annual temperatures over 29°C, which is outside the human climate niche and can be fatal. That means a just boundary for climate is nearer to 1°C. This makes the need to halt further carbon emissions even more urgent. </p>
<p><strong>2. Biosphere boundaries: Expand intact ecosystems to cover 50-60% of the earth</strong></p>
<p>A healthy <a href="https://earthcommission.org/biosphere/">biosphere</a> ensures a safe and just planet by storing carbon, maintaining global water cycles and soil quality, protecting pollinators and many other ecosystem services. To safeguard these services, we need 50 to 60% of the world’s land to have largely intact natural ecosystems. </p>
<p><a href="https://link.springer.com/chapter/10.1007/978-3-031-15703-5_25#DOI">Recent research</a> puts the current figure at between 45% and 50%, which includes vast areas of land with relatively low populations, including parts of Australia and the Amazon rainforest. These areas are already <a href="https://doi.org/10.1073/pnas.0804619106">under pressure</a> from climate change and other human activity.</p>
<p>Locally, we need about 20-25% of each square kilometre of farms, towns, cities or other human-dominated landscapes <a href="https://www.biorxiv.org/content/10.1101/2022.06.24.497294v3">to contain</a> largely intact natural ecosystems. At present, only a third of our human-dominated landscapes meet this threshold.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/529251/original/file-20230531-23-r7u0i4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="walkway over river" src="https://images.theconversation.com/files/529251/original/file-20230531-23-r7u0i4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/529251/original/file-20230531-23-r7u0i4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/529251/original/file-20230531-23-r7u0i4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/529251/original/file-20230531-23-r7u0i4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/529251/original/file-20230531-23-r7u0i4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/529251/original/file-20230531-23-r7u0i4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/529251/original/file-20230531-23-r7u0i4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">To safeguard the biosphere means making sure natural ecosystems survive even in human-dominated areas.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p><strong>3. Freshwater boundaries: Keep groundwater levels up and don’t suck rivers dry</strong></p>
<p>Too much freshwater is a problem, as unprecedented floods in Australia and Pakistan show. And too little is also a problem, with unprecedented droughts taking their toll on food production. </p>
<p>To bring fresh water systems back into balance, a rule of thumb is to avoid <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/rra.1511">taking or adding</a> more than 20% of a river or stream’s water in any one month, in the absence of local knowledge of environmental flows. </p>
<p>At present, 66% of the world’s land area meets this boundary, when flows are averaged over the year. But human settlement has a major impact: less than half of the world’s population lives in these areas. Groundwater, too, is overused. At present, almost half the world’s land is subject to groundwater overextraction. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/529250/original/file-20230531-27-iw50k4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="well with bucket water" src="https://images.theconversation.com/files/529250/original/file-20230531-27-iw50k4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/529250/original/file-20230531-27-iw50k4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=486&fit=crop&dpr=1 600w, https://images.theconversation.com/files/529250/original/file-20230531-27-iw50k4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=486&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/529250/original/file-20230531-27-iw50k4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=486&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/529250/original/file-20230531-27-iw50k4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=611&fit=crop&dpr=1 754w, https://images.theconversation.com/files/529250/original/file-20230531-27-iw50k4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=611&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/529250/original/file-20230531-27-iw50k4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=611&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fresh water is vital to life on land. Over-extraction is dangerous.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p><strong>4. Fertiliser and nutrient boundaries: Halve the runoff from fertilisers</strong></p>
<p>When farmers overuse fertilisers on their fields, rain washes <a href="https://earthcommission.org/nutrients">nitrogen and phosphorus</a> runoff into rivers and oceans. These nutrients can trigger algal blooms, damage ecosystems and worsen drinking water quality. </p>
<p>Yet many farming regions in poorer countries <a href="https://www.annualreviews.org/doi/10.1146/annurev-environ-010213-113300">don’t have enough</a> fertiliser, which is unjust. </p>
<p>Worldwide, our nitrogen and phosphorus use are up to double their safe and just boundaries. While this needs to be reduced in many countries, in other parts of the world fertiliser use can safely increase.</p>
<p><strong>5. Aerosol pollution boundary: Sharply reduce dangerous air pollution and reduce regional differences</strong></p>
<p><a href="https://doi.org/10.1007/s00382-023-06799-3">New research</a> shows differences in concentration of <a href="https://earthcommission.org/aerosols/">aerosol pollutants</a> between Northern and Southern hemispheres could disrupt wind patterns and monsoons if pollutant levels keep increasing. That is, air pollution could actually upend weather systems. </p>
<p>At present, aerosol concentrations have not yet reached weather-changing levels. But much of the world is exposed to dangerous levels of fine particle pollution (known as PM 2.5) in the air, causing <a href="https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(17)30505-6/fulltext">an estimated</a> 4.2 million deaths a year. </p>
<p>We must significantly reduce these pollutants to safer levels – under 15 micrograms per cubic metre of air. </p>
<h2>We must act</h2>
<p>We must urgently navigate towards a <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020EF001866">safe and just</a> future, and strive to return our planetary systems back within safe and just boundaries through just means.</p>
<p>To stop human civilisation from pushing the Earths’s systems out of balance, we will have to tackle the many ways we damage the planet. </p>
<p>To work towards a world compatible with the Earth’s limits means setting and achieving <a href="https://sciencebasedtargetsnetwork.org/">science-based targets</a>. To <a href="https://www.nature.com/articles/d41586-022-02894-3">translate these boundaries</a> to actions will require urgent support from government to create regulatory and incentive-based systems to drive the changes needed. </p>
<p>Setting boundaries and targets is vital. The Paris Agreement galvanised faster action on climate. But we need similar boundaries to ensure the future holds fresh water, clean air, a planet still full of life and a good life for humans.</p>
<p><em>We would like to acknowledge support from the <a href="https://earthcommission.org/">Earth Commission</a>, which is hosted by <a href="https://futureearth.org/">Future Earth</a>, and is the science component of the <a href="https://globalcommonsalliance.org/">Global Commons Alliance</a></em></p><img src="https://counter.theconversation.com/content/206678/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Steven J Lade receives funding from the Australian Government (Australian Research Council Future Fellowship FT200100381) and the Swedish Research Council Formas (Grant 2020-00371). He is affiliated with Future Earth and the Stockholm Resilience Centre at Stockholm University. This work is part of the Earth Commission, which is hosted by Future
Earth and is the science component of the Global Commons Alliance. The Global Commons Alliance is a sponsored project of Rockefeller Philanthropy Advisors, with support from the Oak Foundation, MAVA, Porticus, the Gordon and Betty Moore Foundation, the Tiina and Antti Herlin Foundation, William and Flora Hewlett Foundation and the Global Environment
Facility. The Earth Commission is also supported by the Global Challenges Foundation and the Frontiers Research Foundation.</span></em></p><p class="fine-print"><em><span>Ben Stewart-Koster receives funding from Future Earth for his role in the Earth Commission under the Global Commons Alliance. The Global Commons Alliance is a sponsored project of Rockefeller Philanthropy Advisors, with support from the Oak Foundation, MAVA, Porticus, the Gordon and Betty Moore Foundation, the Tiina and Antti Herlin Foundation, William and Flora Hewlett Foundation and the Global Environment Facility. The Earth Commission is also supported by the Global Challenges Foundation and the Frontiers Research Foundation.. </span></em></p><p class="fine-print"><em><span>Stuart Bunn receives funding from Future Earth for his role in the Earth Commission under the Global Commons Alliance. This is a sponsored project of Rockefeller Philanthropy Advisors, with support from the Oak Foundation, MAVA, Porticus, the Gordon and Betty Moore Foundation, the Tiina and Antti Herlin Foundation, William and Flora Hewlett Foundation and the Global Environment Facility. The Earth Commission is also supported by the Global Challenges Foundation and the Frontiers Research Foundation. </span></em></p><p class="fine-print"><em><span>Syezlin Hasan receives funding from Future Earth for her role in the Earth Commission under the Global Commons Alliance. The Global Commons Alliance is a sponsored project of Rockefeller Philanthropy Advisors, with support from the Oak Foundation, MAVA, Porticus, the Gordon and Betty Moore Foundation, the Tiina and Antti Herlin Foundation, William and Flora Hewlett Foundation and the Global Environment Facility. The Earth Commission is also supported by the Global Challenges Foundation and the Frontiers Research Foundation. </span></em></p><p class="fine-print"><em><span>This paper was made possible through the voluntary commitment of
time and research by the Earth Commissioners and the support of the
researchers and secretariat from the Global Challenges Foundation;
the Global Commons Alliance, a sponsored project of Rockefeller
Philanthropy Advisors (with support from Oak Foundation, MAVA,
Porticus, Gordon and Betty Moore Foundation, Herlin Foundation and
the Global Environment Facility).</span></em></p>We’ve blown past the safe and just limit for vital Earth systems, from climate change to the biosphere and the use of fertilisers and freshwater. For humans to thrive means living in safe limitsSteven J Lade, Resilience researcher at Australian National University, Australian National UniversityBen Stewart-Koster, Senior research fellow, Griffith UniversityStuart Bunn, Professor, Australian Rivers Institute, Griffith UniversitySyezlin Hasan, Research fellow, Griffith UniversityXuemei Bai, Distinguished Professor, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2022852023-03-22T15:07:53Z2023-03-22T15:07:53ZFreshwater ecosystems are becoming increasingly salty. Here’s why this is a concern<figure><img src="https://images.theconversation.com/files/516784/original/file-20230321-502-l9q2xx.jpeg?ixlib=rb-1.1.0&rect=17%2C28%2C3844%2C2860&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Roads require de-icing strategies in northern regions, but this practice has negative effects on aquatic biodiversity.</span> <span class="attribution"><span class="license">Author provided</span></span></figcaption></figure><p>Freshwater ecosystems around the world <a href="https://doi.org/10.1126/science.aad3488">are becoming saltier and saltier</a>. Many human-driven factors contribute to freshwater salinization, including: irrigation, oil extraction, <a href="https://ici.radio-canada.ca/nouvelle/1287569/mine-potasse-saskatchewan-sedley-environnement-pollution">potash mining</a>, and <a href="https://theconversation.com/laccumulation-des-sels-de-deglacage-dans-les-lacs-menace-ceux-qui-y-vivent-179166">road de-icing</a>. </p>
<p>As a result, salts enter waterways. But as bad news never comes alone, the salts are often accompanied by a toxic cocktail of other pollutants, whose combined toxicological effects are <a href="https://doi.org/10.1073/pnas.1711234115">largely unknown</a>.</p>
<p>Although the problem of rising freshwater salinization went largely unaddressed <a href="https://doi.org/10.1007/978-94-017-2934-5_30">for many decades</a>, it has gained considerable attention<a href="https://doi.org/10.1073/pnas.0507389102"> during the last 20 years</a>. </p>
<p>Scientists around the world are working together to understand the ecological impacts of increasing salinization on aquatic biodiversity and food webs. Our ultimate goal? To examine the adequacy of water quality toxicity thresholds for the protection of aquatic life. </p>
<h2>Salinization, a major problem</h2>
<p>Canada is home to a majority of the world’s freshwater resources, mostly concentrated in the provinces <a href="https://doi.org/10.1038/ncomms13603">of Ontario and Québec</a>, where close to 5 million tons of road salt are applied annually <a href="https://www.canada.ca/en/environment-climate-change/services/pollutants/road-salts/code-practice-environmental-management.html">to de-ice roads</a>. </p>
<p>Combined with climate change and increasing frequency and duration of drought in many regions of the world, <a href="https://doi.org/10.1038/nclimate1633">the problem is getting worse</a>. This is a major concern. Why? Because the availability of freshwater resources will become a critical factor for humanity <a href="https://doi.org/10.1073/pnas.1011615108">over the next 50 years</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=380&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=380&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=380&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516786/original/file-20230321-16-qtyme2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The inequitable global distribution of surface freshwater resource availability. (Source: Philippe Rekacewicz, February 2006).</span>
</figcaption>
</figure>
<h2>Researchers from around the world mobilized</h2>
<p>We recently presented a series of articles in a special issue on freshwater salinization in the journal <em>Limnology and Oceanography Letters</em>, <a href="https://doi.org/10.1002/lol2.10307">published last February</a>. </p>
<p>In this special issue, we focus on sodium chloride (NaCl), the same molecule found in table salt, as a key agent of freshwater salinization. We highlight a series of co-ordinated field experiments, conducted by researchers in North America and Europe, that have addressed the impacts of freshwater salinization on <a href="https://www.thecanadianencyclopedia.ca/fr/article/zooplancton">zooplankton</a> (microscopic crustaceans) at a regional scale.</p>
<p>Zooplankton are an ecologically critical group in aquatic food webs and are often used as indicators to detect environmental change due to their sensitive ecological tolerances. </p>
<p>The main conclusions of these experiments are as follows:</p>
<ul>
<li>Water quality guidelines in Canada and the United States (standards) do not adequately protect freshwater zooplankton, which could lead to <a href="https://doi.org/10.1073/pnas.2115033119">an increase in the abundance of algae</a>, which the zooplankton feed on. This is because when zooplankton abundance decreases, especially for large grazers such as Daphnia, phytoplankton can proliferate under conditions of reduced predation; </li>
<li>Salinization of freshwater systematically leads to a loss of abundance and diversity of zooplankton <a href="https://doi.org/10.1002/lol2.10239">in all regions</a>; and </li>
<li>Individuals of the same zooplankton species do not all exhibit the same tolerance to salinity. Thus, this variation may interfere with our ability to predict community-level responses. Water quality guidelines may therefore need to be adjusted to become <a href="https://doi.org/10.1002/lol2.10277">more region-specific</a>.</li>
</ul>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516423/original/file-20230320-16-m9r9yu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Regional coverage of a co-ordinated field mesocosm experiment (Hintz et al. 2022b, Hébert et al. 2022; Arnott et al. 2022), with an example of one of the experiments that was conducted at Lac Croche (Québec, Canada) (Astorg et al. 2022) (Figure modified from Hintz et al. 2022b).</span>
</figcaption>
</figure>
<h2>A matter of regulation</h2>
<p>Many questions remain unanswered. However, what we do now know is that long-term water quality guidelines (Canada: 120 mg Cl⁻¹L⁻¹; United States: 230 mg Cl⁻¹L⁻¹) and in the short term (Canada: 640 mg Cl⁻¹L⁻¹; United States: 860 mg Cl⁻¹L⁻¹) for chloride concentrations are too high to protect aquatic life <a href="https://doi.org/10.1021/acs.est.0c02396">in Canada and in the United States</a>. For reference, a pinch of salt in a pot of water corresponds to approximately 0.3 mg of Cl⁻¹/L⁻¹. In other words, adverse effects are observed at much lower concentrations. Regulations in Canada and the United States should therefore be reviewed. In Europe, the water quality standards for salinity <a href="https://doi.org/10.1098/rstb.2018.0019">for the protection of aquatic life in freshwater ecosystems are mostly absent</a>. </p>
<h2>The importance of taking concrete action</h2>
<p>Water quality guidelines for the protection of aquatic life are generally established using laboratory tests (called toxicological tests) <a href="https://doi.org/10.1002/lol2.10208">on a single species</a>. </p>
<p>However, aquatic habitats harbour a complex array of predators, prey, competitors, and pathogens, the interactions of which can limit our ability to <a href="https://doi.org/10.1016/j.scitotenv.2013.01.066">predict the responses of communities and species to pollutants </a>. </p>
<p>Thus, the collective research published in this special issue also highlights the importance of understanding ecological responses in multi-species communities in natural settings to assess <a href="https://doi.org/10.1073/pnas.2115033119">the responses of freshwater life to human impacts</a>. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/516409/original/file-20230320-1978-kggv7i.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Aerial view of a field enclosure experiment conducted in a chloride-sensitive lake in the Laurentians (Québec) (Astorg et al. 2022) (Photo credit: Étienne Laliberté).</span>
</figcaption>
</figure>
<p>Overall, we should develop alternative applications and technologies that are <a href="https://doi.org/10.1007/s11270-011-1064-6">more sustainable and efficient</a>.</p>
<p>We also need to establish <a href="https://doi.org/10.1098/rstb.2018.0019">more appropriate water quality guidelines</a> to improve controls on salts entering our freshwater environments to reduce adverse effects on aquatic life <a href="https://doi.org/10.1007/s10533-021-00784-w">and the quality of our freshwater resources</a>.</p><img src="https://counter.theconversation.com/content/202285/count.gif" alt="La Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Les auteurs ne travaillent pas, ne conseillent pas, ne possèdent pas de parts, ne reçoivent pas de fonds d'une organisation qui pourrait tirer profit de cet article, et n'ont déclaré aucune autre affiliation que leur organisme de recherche.</span></em></p>Although it has been considerably less studied than other environmental problems, salinization presents major challenges for biodiversity in freshwater and coastal areas.Alison Derry, Professeure agrégée, Université du Québec à Montréal (UQAM)Miguel Cañedo-Argüelles, Profesor lector en Ecología, Universitat de BarcelonaStephanie J Melles, Associate Professor, Spatial Ecology, Toronto Metropolitan UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2017042023-03-21T08:58:39Z2023-03-21T08:58:39ZAfrica’s aquifers hold more than 20 times the water stored in the continent’s lakes, but they aren’t the answer to water scarcity<figure><img src="https://images.theconversation.com/files/515190/original/file-20230314-2482-5vni0b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Giordano Cipriani/Getty Images</span></span></figcaption></figure><p>Discoveries of aquifers – underground earth formations that hold water – often create excitement around their ability to ease water scarcity in a region. </p>
<p>For instance, about 10 years ago a large aquifer was <a href="https://www.bbc.com/news/science-environment-24049800">discovered</a> in Kenya’s Turkana region. This is one of the hottest, driest parts of Kenya and it frequently suffers from drought. The government claimed that the aquifer could supply the entire country with water for 70 years. More recently, the US announced the <a href="https://www.state.gov/secretary-antony-j-blinken-at-a-press-availability-31/">discovery</a> of five aquifers in Niger, one of Africa’s <a href="https://washdata.org/data/household#!/ner">most water scarce</a> countries, containing over 600 billion cubic metres of water. To put it into perspective, Egypt’s current water demand is <a href="https://www.tandfonline.com/doi/full/10.1080/02508060.2021.1921503">114 billion cubic metres</a> of water per year. </p>
<p>These are welcome announcements. Due to a changing climate and the increasing demands of a growing population, <a href="https://theconversation.com/worrying-insights-from-uns-first-ever-assessment-of-water-security-in-africa-179577#:%7E:text=Only%2013%20of%2054%20countries,to%20reach%20an%20acceptable%20level.">many of Africa’s surface water resources</a> – such as dams and rivers – are under strain. They’re being overused and slowly depleted. </p>
<p>Alternative water sources, like aquifers, need to be explored. Based on Africa’s geology we know aquifers are <a href="https://iopscience.iop.org/article/10.1088/1748-9326/abd661">highly prevalent</a> across the continent. But, as a groundwater and aquifer expert, I want to highlight that they’re not always going to help address water scarcity. For instance, early research findings <a href="https://www.standardmedia.co.ke/rift-valley/article/2001440969/residents-hope-dimmed-as-aquafer-water-unfit-for-use">deemed</a> Kenya’s Turkana aquifer water unfit for use due to high salinity.</p>
<p>It’s important to bear these challenges in mind so that expectations can be managed. It is also useful for planners and governments, as they need to think of other ways around the water scarcity problem.</p>
<h2>Africa’s aquifers</h2>
<p>The volume of groundwater that’s held in African aquifers is <a href="https://iopscience.iop.org/article/10.1088/1748-9326/7/2/024009">estimated to be</a> 0.66 million km³. This is more than 100 times the annual renewable freshwater resources stored in dams and rivers, and 20 times the freshwater stored in Africa’s lakes. </p>
<p>The size and shape of an aquifer is <a href="https://www.epa.gov/sites/default/files/documents/groundwater.pdf">based</a> on the body of rock beneath the Earth’s surface. Some can be in the form of caves and hold water on a large scale. Some can range from a few metres thick to hundreds of metres with multiple layers. Aquifers can also extend for many kilometres or be localised in certain areas. </p>
<p>Water gets into these aquifers in different ways. Some are filled by new rainfall, others hold old, or ancient, rainfall. In Africa, most are found less than <a href="https://iopscience.iop.org/article/10.1088/1748-9326/7/2/024009">50 metres</a> below the ground’s surface.</p>
<p>Many of Africa’s aquifers are <a href="https://www.un-igrac.org/resource/transboundary-aquifers-africa-map-2022">spread across country borders</a>, meaning countries have to share the water resource. The largest volumes of groundwater in Africa are <a href="https://iopscience.iop.org/article/10.1088/1748-9326/7/2/024009">found in</a> large aquifers in Libya, Algeria, Egypt and Sudan.</p>
<p>There are various ways to tap into aquifers, including hand-dug wells, drilled wells and boreholes, and <a href="https://www.mysuwanneeriver.com/56/What-is-a-Spring#:%7E:text=As%20rainwater%20enters%20or%20%22recharges,surface%20at%20places%20called%20springs">natural springs</a>. </p>
<h2>Tapping into the groundwater</h2>
<p>Some countries have already taken steps to tap into aquifers. </p>
<p>South Africa has two massive aquifers. The largest stretches from Cape Town to Gqeberha, a city 750km away. This geological formation <a href="https://core.ac.uk/download/pdf/58914805.pdf">covers</a> a surface area of 37,000km² and ranges in thickness from 900 metres to 4,000 metres. The other big one is the Cape Flats aquifer. It is estimated that by 2036, almost R5 billion (about US$274 million) will have been invested to tap these aquifers. They will yield about half of the amount of water in the Berg River dam, which provides <a href="https://www.sanews.gov.za/south-africa/r15bil-berg-river-dam-supply-20-cape-towns-water">almost 20%</a> of the City of Cape Town’s supply.</p>
<p>Another large aquifer on the continent, containing only ancient trapped water, is the <a href="https://www-naweb.iaea.org/napc/ih/documents/factsheetsPosters/Nubian%20-%20Transboundary%20Aquifers%20and%20Rivers%20Basins.pdf">Nubian Sandstone</a> in North Africa. It covers about 2 million km², and spans Libya, Egypt, Sudan and Chad. It contains more than 150,000km³ of groundwater – more water than the Nile River <a href="https://eos.org/articles/ancient-water-underlies-arid-egypt">discharges</a> in 500 years. The countries it spans <a href="https://reliefweb.int/report/chad/four-african-nations-agree-water-management-programme">are tapping</a> into the aquifer and have agreed on its fair use. </p>
<p>Libya has undertaken the <a href="https://www.researchgate.net/publication/356666715_The_Great_Man-_Made_River_Project">Great Man-Made River project</a> to pipe water hundreds of kilometres from the Nubian sandstone to the coast by means of gravity flow. </p>
<h2>Challenges in using aquifers</h2>
<p>But aquifers aren’t a silver bullet. There are many factors to consider when using them as a water source. </p>
<p><strong>Distance</strong></p>
<p>The distance between the aquifer and where the water is needed can be an obstacle. In some places in Africa, this distance is covered by women carrying buckets and walking for many kilometres. The construction of pipelines and infrastructure can be costly.</p>
<p>A related challenge is the depth required to drill for groundwater, which can incur great costs. A type of X-ray is done of the surface to confirm whether there are groundwater resources worth exploiting, and then there’s the expense of a drilling rig. </p>
<p><strong>Water quality</strong></p>
<p>Water quality in an aquifer isn’t always good. Sometimes it’s polluted by human activity; sometimes the water takes on characteristics of the surrounding material in the ground. </p>
<p>An example is outside Gqeberha, which has one of the largest drilled wells in the Southern Hemisphere. It yields about 100 litres per second. Unfortunately the iron content of the water is <a href="https://issuu.com/glen.t/docs/imiesa_august_2020/s/10926142">above the required standards</a>. It has to be treated before it is drinkable. </p>
<p><strong>Unsustainable groundwater use</strong></p>
<p>Overpumping is becoming common in certain areas, especially cities. <a href="https://www.researchgate.net/publication/223625261_The_use_of_garden_boreholes_in_Cape_Town_South_Africa_Lessons_learnt_from_Perth_Western_Australia">Cape Town</a> and <a href="https://www.the-star.co.ke/counties/nairobi/2019-01-17-no-more-boreholes-to-be-drilled-water-table-dropping-warns-cs/">Nairobi</a> are reporting hundreds of well points being drilled for residents to use. Cases of wells drying up and water levels dropping rapidly <a href="https://www.science.org/doi/10.1126/science.abc2755">have been reported</a> in places.</p>
<p>Industrial activity, agriculture and chemical leaks can also affect groundwater quality.</p>
<p>Overpumping can also cause seawater to get into groundwater. The more dense seawater migrates to replace the freshwater removed from an aquifer. This has devastating implications for the storage capacity of the aquifers as well as the overall groundwater quality. It has been seen in <a href="https://www.sciencedirect.com/science/article/pii/S246822762030140X#:%7E:text=The%20intrusion%20of%20seawater%20into,are%20the%20unconfined%20coastal%20aquifers">certain coastal aquifers</a>. Saline intrusions are very difficult to address.</p>
<h2>Meeting water needs</h2>
<p>Despite these concerns, aquifers have the capacity to provide some water in almost all parts of Africa. Groundwater is part of the solution to water scarcity, but not the entire solution. It should be used in a way that keeps it available long into the future.</p><img src="https://counter.theconversation.com/content/201704/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gaathier Mahed does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Aquifers are highly prevalent across Africa – but they’re not always going to be usable.Gaathier Mahed, Senior lecturer, Nelson Mandela UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1971932023-01-15T14:36:12Z2023-01-15T14:36:12ZCanada, a superpower? Here’s how the country might one day fit the bill<figure><img src="https://images.theconversation.com/files/503627/original/file-20230109-7526-b6x4xo.JPG?ixlib=rb-1.1.0&rect=0%2C0%2C3300%2C2129&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A paddler launches a canoe on Bass Lake in central Ontario on Canada Day, 2021. Could humble Canada be heading towards superpower status in the decades to come?</span> <span class="attribution"><span class="source">THE CANADIAN PRESS/Fred Thornhill</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/canada--a-superpower-here-s-how-the-country-might-one-day-fit-the-bill" width="100%" height="400"></iframe>
<p>For the foreseeable future, <a href="https://now.tufts.edu/2019/11/21/why-united-states-only-superpower">the United States will probably remain the world’s most powerful nation</a>. Yet, like any champion, it must watch for challengers and head them off. At present, <a href="https://www.theatlantic.com/international/archive/2021/10/evergrande-china-us/620360/">China’s rise on the global stage troubles Washington</a>. A few decades ago, it was the Soviet Union.</p>
<p>But will future contenders for superpower status be much closer — specifically, north of the U.S. border? The British Empire ended in the mid-20th century when it was outmanoeuvred not by one of its longtime rivals, France or Germany, but rather by its ally, the U.S. Could Canada do the same?</p>
<p><a href="https://www150.statcan.gc.ca/n1/pub/71-607-x/71-607-x2018005-eng.htm">Canada’s population</a> is just a fraction <a href="https://www.census.gov/popclock/">of its southern neighbour’s</a>, but Prime Minister Justin Trudeau’s Liberal government has announced an <a href="https://www.cbc.ca/news/politics/canada-immigration-500000-2025-1.6636661">ambitious plan to bring in 500,000 immigrants each year</a> by 2025.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-canada-plans-to-break-records-with-its-new-refugee-targets-193880">How Canada plans to break records with its new refugee targets</a>
</strong>
</em>
</p>
<hr>
<p>The vast majority will be young and selected via merit-based criteria that give priority to education and workplace skills. Canada’s population in relation to the U.S. has also been slowly increasing for decades and <a href="https://www150.statcan.gc.ca/n1/daily-quotidien/220209/cg-a001-eng.htm">is growing at a faster pace.</a></p>
<p>Canada and the U.S. are roughly the same size, both accounting for <a href="https://www.worldometers.info/geography/largest-countries-in-the-world/">6.1 per cent of the world’s land mass</a>. Much of Canada’s land at present is cold, barren and largely uninhabitable. But climate change has made Canada’s landscape more temperate and <a href="https://www.ctvnews.ca/could-global-warming-turn-canada-into-a-superpower-1.556373">suitable for agriculture and other activities</a>, a trend expected to continue in the decades to come. </p>
<figure class="align-center ">
<img alt="Ships are seen on open water behind a large chunk of blue-ish sea ice." src="https://images.theconversation.com/files/503628/original/file-20230109-15599-kauvwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/503628/original/file-20230109-15599-kauvwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/503628/original/file-20230109-15599-kauvwj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/503628/original/file-20230109-15599-kauvwj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/503628/original/file-20230109-15599-kauvwj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/503628/original/file-20230109-15599-kauvwj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/503628/original/file-20230109-15599-kauvwj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Ships are framed by pieces of melting sea ice in Frobisher Bay in Iqaluit, Nunavut in July 2019.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Sean Kilpatrick</span></span>
</figcaption>
</figure>
<h2>Economic powerhouse</h2>
<p>In some ways Canada is already a superpower. Its economic output is the <a href="https://www.visualcapitalist.com/countries-by-share-of-global-economy/">eighth largest in the world</a>. The seven countries with larger economies have bigger populations than Canada. Even with a short growing season and relatively small area devoted to agriculture, Canada is the <a href="https://agriculture.canada.ca/en/sector/overview">fifth largest exporter of agri-food and seafood products</a>. </p>
<p>But economic strength is only one measure of a global power. Another is having the resources that others need. In that regard, Canada is extraordinarily rich in natural resources, including clean water. Regardless of future economic, environmental and technological trends, the country will be an energy and natural resources superpower. </p>
<figure class="align-center ">
<img alt="An aerial shot of a large array of lakes." src="https://images.theconversation.com/files/504082/original/file-20230111-32622-hgpv75.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/504082/original/file-20230111-32622-hgpv75.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/504082/original/file-20230111-32622-hgpv75.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/504082/original/file-20230111-32622-hgpv75.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/504082/original/file-20230111-32622-hgpv75.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/504082/original/file-20230111-32622-hgpv75.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/504082/original/file-20230111-32622-hgpv75.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Canada has an abundance of fresh water.</span>
<span class="attribution"><span class="source">(Sergei A, Unsplash)</span></span>
</figcaption>
</figure>
<p>Two other elements are needed for <a href="https://www.foreignaffairs.com/articles/united-states/2022-06-21/what-makes-a-power-great">superpower status</a>: a political system that provides strong governance and a national culture that’s appealing to its own citizens and to people around the world. </p>
<p>Canadian politics prizes stability and moderation, both hallmarks of a superpower. Social change occurs with few ideological battles. For example, becoming the first developed country to legalize <a href="https://www.voanews.com/a/legal-marijuana-makes-few-waves-in-canada/6718512.html">the use and sale of recreational cannabis</a> happened with scant controversy or social division. </p>
<p>Even on <a href="https://www.ctvnews.ca/politics/liberal-government-seeking-delay-to-expanding-medically-assisted-dying-program-1.6196668">expanding the scope of medical assistance in dying legislation</a>, Canadians have remained civil, with all stakeholders willing to listen to each other. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/health-care-providers-and-maid-the-reasons-why-some-dont-offer-medically-assisted-death-186625">Health-care providers and MAID: The reasons why some don't offer medically assisted death</a>
</strong>
</em>
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<h2>Providing inspiration</h2>
<p>Superpowers are not only countries that dominate in various spheres, but also countries that command the aspiration of — and provide inspiration for — people around the globe. For two centuries, the U.S. has made its national dream one that others around the world sought to attain. American-style democracy was the gold standard. </p>
<p>This is now less and less the case. The “city on a hill” acting as <a href="https://www.michigandaily.com/opinion/columns/the-new-world-order-america-in-decline/">a beacon of hope for others</a> has morphed in recent decades into a selfish “America-first” environment. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/503637/original/file-20230109-9407-cwhwi1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A man with orange-blonde hair speaks with his arms spread behind a podium that says Trump. American flags are behind him." src="https://images.theconversation.com/files/503637/original/file-20230109-9407-cwhwi1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/503637/original/file-20230109-9407-cwhwi1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/503637/original/file-20230109-9407-cwhwi1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/503637/original/file-20230109-9407-cwhwi1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/503637/original/file-20230109-9407-cwhwi1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/503637/original/file-20230109-9407-cwhwi1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/503637/original/file-20230109-9407-cwhwi1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Former president Donald Trump announces a third run for president as he speaks at Mar-a-Lago in Palm Beach, Fla., in November 2022.</span>
<span class="attribution"><span class="source">(AP Photo/Rebecca Blackwell)</span></span>
</figcaption>
</figure>
<p><a href="https://www.pewresearch.org/politics/2014/06/12/political-polarization-in-the-american-public/">American citizens have grown disillusioned by their polarized politics</a>, while outsiders question the excesses that drive U.S. capitalism. Donald Trump’s years in the White House have left many <a href="https://www.pewresearch.org/2021/01/29/how-america-changed-during-donald-trumps-presidency/">dismayed about the future</a> of their country and widened the divisions between Republicans and Democrats. </p>
<p>As neighbours, Canadians shake their heads in wonder at the inequities, lack of public health care, lax gun control and debates over abortion and immigration that dominate and <a href="https://www.environicsinstitute.org/insights/insight-details/we-re-witnessing-the-continuing-cultural-divergence-of-canada-and-the-united-states">divide American politics</a>. </p>
<p>Canadian culture, shaped by the country’s history of being a fragment of both the British and French empires, has aspired to promote equality, both between individuals and groups, although it’s failed in its abysmal treatment of Indigenous Peoples.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/delgamuukw-25-years-on-how-canada-has-undermined-the-landmark-decision-on-indigenous-land-rights-196196">Delgamuukw 25 years on: How Canada has undermined the landmark decision on Indigenous land rights</a>
</strong>
</em>
</p>
<hr>
<p>Nonetheless, in an age of globalization and demand for greater personal freedoms, Canada’s <a href="https://thewalrus.ca/canadian-multiculturalism-a-work-in-progress/?gclid=CjwKCAiA8OmdBhAgEiwAShr40-sSjf2t9aarxeliFshUw2DdiDnNGQbUmrKvtGi9uzLhaEWXx9ZFExoCcDgQAvD_BwE">multicultural policies are a beacon of hope</a> in a world often scarred by religious, ethnic and tribal battles. </p>
<h2>Where will Canada be in 2223?</h2>
<p>Much like when the U.S. steadily assumed the role of unchallenged superpower from Great Britain during the first half of the 20th century, it might be that <a href="https://policyoptions.irpp.org/magazines/june-2020/why-canada-may-become-a-great-global-power-this-century/">Canada gradually becomes a great power</a> this century — perhaps first as a partner to the United States, but then increasingly supplanting its neighbour. </p>
<p>For many around the world, such a transition would be preferable to other scenarios, such as China or Russia assuming more dominant roles in global affairs.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/united-states-the-end-of-an-illusion-of-omnipotence-186421">United States: the end of an illusion of omnipotence</a>
</strong>
</em>
</p>
<hr>
<p>A shift in global power relations would occur at a leisurely pace and with minimal disruption. </p>
<p>In 1776, with a population of 2.5 million, few imagined that within two centuries, the U.S. would become the dominant superpower. It’s not inconceivable that Canada could perform the same feat by 2223.</p><img src="https://counter.theconversation.com/content/197193/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thomas Klassen does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>In 1776, with a population of 2.5 million, few imagined that within two centuries, the U.S. would become the dominant superpower. It’s not inconceivable that Canada could do the same by 2223.Thomas Klassen, Professor, School of Public Policy and Administration, York University, CanadaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1971682023-01-06T13:32:37Z2023-01-06T13:32:37ZHow California could save up its rain to ease future droughts — instead of watching epic atmospheric river rainfall drain into the Pacific<figure><img src="https://images.theconversation.com/files/503361/original/file-20230105-24-8a0umi.jpg?ixlib=rb-1.1.0&rect=0%2C16%2C5472%2C3620&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Heavy rain from a series of atmospheric rivers flooded large parts of California from late December 2022 into early January 2023.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/view-of-highway-101-flooding-in-south-san-francisco-as-news-photo/1245913492">Tayfun Coskun/Anadolu Agency via Getty Images</a></span></figcaption></figure><p>California has seen <a href="https://www.washingtonpost.com/weather/2023/01/01/san-francisco-flooding-rainfall-record/">so much rain</a> over the past few weeks that farm fields are inundated and normally dry creeks and drainage ditches have become torrents of water racing toward the ocean. Yet, most of the state <a href="https://droughtmonitor.unl.edu/data/png/20230103/20230103_west_text.png">remains in drought</a>.</p>
<p>All that runoff in the middle of a drought begs the question — why can’t more rainwater be collected and stored for the long, dry spring and summer when it’s needed?</p>
<p>As a <a href="https://eps.ucsc.edu/faculty/Profiles/fac-only.php?uid=afisher">hydrogeologist</a> at the University of California at Santa Cruz, I’m interested in what can be done to collect runoff from storms like this on a large scale. There are two primary sources of large-scale water storage that could help make a dent in the drought: holding that water behind dams and putting it in the ground.</p>
<h2>Why isn’t California capturing more runoff now?</h2>
<p>When California gets storms like the <a href="https://earthobservatory.nasa.gov/images/150804/atmospheric-river-lashes-california">atmospheric rivers</a> that hit in December 2022 and January 2023, water managers around the state probably shake their heads and ask why they can’t hold on to more of that water. The reality is, it’s a complicated issue.</p>
<p>California has <a href="https://cdec.water.ca.gov/resapp/RescondMain">big dams and reservoirs</a> that can store large volumes of water, but they tend to be in the mountains. And once they’re near capacity, water has to be released to be ready for the next storm. Unless there’s another reservoir downstream, a lot of that water is going out to the ocean.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/sKx-wSICxQQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A video captures flooding from record rainfall on the last weekend of 2022.</span></figcaption>
</figure>
<p>In more populated areas, one of the reasons storm water runoff isn’t automatically collected for use on a large scale is because the first runoff from roads is <a href="https://doi.org/10.1007/s00244-021-00906-3">often contaminated</a>. Flooding can also cause <a href="https://www.bio-sol.ca/blog/en/septic-system-during-heavy-rain/">septic system overflows</a>. So, that water would have to be treated.</p>
<p>You might say, well, the captured water doesn’t have to be drinking water, we could just use it on golf courses. But then you would need a place to store the water, and you would need a way to distribute it, with separate pipes and pumps, because you can’t put it in the same pipes as drinking water.</p>
<h2>Putting water in the ground</h2>
<p>There’s another option, and that’s to put it in the ground, where it could help to replenish groundwater supplies.</p>
<p>Managed recharge has been used for decades in <a href="http://www.fresnofloodcontrol.org/groundwater-recharge/">many areas</a> to actively replenish groundwater supplies. But the techniques have been gaining more attention lately as wells run dry amid the long-running drought. Local agencies have proposed more than <a href="https://resources.ca.gov/-/media/CNRA-Website/Files/Initiatives/Water-Resilience/CA-Water-Supply-Strategy.pdf">340 recharge projects</a> in California, and the state estimates those could recharge an additional 500,000 <a href="https://www.watereducation.org/general-information/whats-acre-foot">acre-feet</a> of water a year on average if all were built.</p>
<p>One method being discussed by the state Department of Water Resources and others is <a href="https://water.ca.gov/programs/all-programs/flood-mar">Flood-MAR, or flood-managed aquifer recharge</a>. During big flows in rivers, water managers could potentially divert some of that flow onto large parts of the landscape and inundate thousands of acres to recharge the aquifers below. The concept is to flood the land in winter and then farm in summer.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/502983/original/file-20230103-64877-pfntf2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Illustration showing different techniques with fields flooded in different ways" src="https://images.theconversation.com/files/502983/original/file-20230103-64877-pfntf2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/502983/original/file-20230103-64877-pfntf2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=737&fit=crop&dpr=1 600w, https://images.theconversation.com/files/502983/original/file-20230103-64877-pfntf2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=737&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/502983/original/file-20230103-64877-pfntf2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=737&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/502983/original/file-20230103-64877-pfntf2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=926&fit=crop&dpr=1 754w, https://images.theconversation.com/files/502983/original/file-20230103-64877-pfntf2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=926&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/502983/original/file-20230103-64877-pfntf2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=926&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Flood-managed aquifer recharge methods.</span>
<span class="attribution"><a class="source" href="https://water.ca.gov/programs/all-programs/flood-mar">California Department of Water Resources</a></span>
</figcaption>
</figure>
<p>Flood-MAR is promising, provided we can find people who are willing to inundate their land and can secure water rights. In addition, not every part of the landscape is prepared to take that water.</p>
<p>You could inundate 1,000 acres on a ranch, and a lot of it might stay flooded for days or weeks. Depending on how quickly that water soaks in, some crops will be OK, but other crops could be harmed. There are also concerns about creating habitat that encourages pests or risks food safety.</p>
<p>Another challenge is that most of the big river flows are in the northern part of the state, and many of the areas experiencing the <a href="https://www.ppic.org/publication/groundwater-recharge/">worst groundwater deficits</a> are in central and southern California. To get that excess water to the places that need it requires transport and distribution, which can be complex and expensive.</p>
<h2>Encouraging landowners to get involved</h2>
<p>In the Pajaro Valley, an important agricultural region at the edge of Monterey Bay, regional colleagues and I are trying <a href="https://www.youtube.com/watch?v=U_BtWaM3SC4">a different type of groundwater recharge project</a> where there is a lot of runoff from hill slopes during big storms.</p>
<p>The idea is to siphon off some of that runoff and divert it to infiltration basins, occupying a few acres, where the water can pool and percolate into the ground. That might be on agricultural land or open space with the right soil conditions. We look for coarse soils that make it easier for water to percolate through gaps between grains. But much of the landscape is covered or underlain by finer soils that don’t allow rapid infiltration, so careful site selection is important.</p>
<p>One program in the Pajaro Valley encourages landowners to participate in recharge projects by giving them a rebate on the fee they pay for water use through a “<a href="https://www.uctv.tv/shows/Recharge-Net-Metering-ReNeM-36130">recharge net metering</a>” mechanism.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/7ZPKqqa6cas?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">How recharge net metering works.</span></figcaption>
</figure>
<p>We did a cost-benefit analysis of this approach and found that even when you add in all the capital costs for construction and hauling away some soil, the costs are competitive with finding alternative supplies of water, and it is cheaper than desalination or water recycling.</p>
<h2>Is the rain enough to end the drought?</h2>
<p>It’s going to take many methods and several wet years to make up for the region’s long period of low rainfall. One storm certainly doesn’t do it, and even one wet year doesn’t do it.</p>
<p>For basins that are dependent on groundwater, the recharge process takes years. If this is the last rainstorm of this season, a month from now we could be in trouble again.</p><img src="https://counter.theconversation.com/content/197168/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Funding: U.S. National Science Foundation, U.S. Department of Agriculture, National Aeronautics and Space Administration, Gordon and Betty Moore Foundation, Santa Clara Valley Water District, U.S. Geologic Survey
Affiliation: Research Network with the Public Policy Institute of California</span></em></p>Urban infrastructure was designed to take stormwater out to the ocean quickly. Now, California needs that precious water.Andrew Fisher, Professor of Earth and Planetary Sciences, University of California, Santa CruzLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1954022022-11-28T16:56:11Z2022-11-28T16:56:11ZMussels are disappearing from the Thames and growing smaller – and it’s partly because the river is cleaner<figure><img src="https://images.theconversation.com/files/497604/original/file-20221128-533-pch8v5.jpg?ixlib=rb-1.1.0&rect=1%2C0%2C997%2C657&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The population of River Thames freshwater mussels has declined by almost 95% since 1964.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/two-large-river-mussels-on-pier-2021878166">BadPixma/Shutterstock</a></span></figcaption></figure><p>Freshwater ecosystems, including rivers, are home to <a href="https://onlinelibrary.wiley.com/doi/epdf/10.1017/S1464793105006950">10% of all known animal species</a>. Yet at the same time, they are losing their <a href="https://livingplanet.panda.org/en-GB/">species diversity</a> faster than any other ecosystem type globally. Because species of animals respond to different threats in various ways, it makes it difficult to assess the health of these river systems.</p>
<p>But the population status of species such as freshwater mussels can reveal wider trends in the ecosystem. Freshwater mussels live in riverbeds and feed by filtering algae and other organic particles from the water. As they burrow into the riverbed and remain largely stationary, they are exposed to many of the stressors threatening rivers and are therefore a useful indicator the health of the river in which they live.</p>
<p>Mussels also serve as ecosystem engineers. They maintain clear water and prevent the development of harmful algal blooms. They also promote freshwater biodiversity by providing habitat and nutrients for <a href="https://onlinelibrary.wiley.com/doi/abs/10.1002/aqc.815">riverbed invertebrates</a>. Freshwater mussels are among the <a href="https://link.springer.com/article/10.1007/s10750-017-3486-7">most threatened animal groups</a> in the world. Yet in Britain we have little information on the health of these species.</p>
<p>I participated in a <a href="https://doi.org/10.1111/1365-2656.13835">recent survey</a> which evaluated the population status of freshwater mussels in the River Thames. We found an alarming deterioration in the number and size of the mussels, which could harm the health of the river ecosystem. But some of the changes we observed may be the outcome of efforts to return the River Thames to a more “natural state”. </p>
<h2>The river’s mussels under threat</h2>
<p><a href="https://www.jstor.org/stable/2489">One influential survey</a>, carried out in 1964, underpins much of our understanding about freshwater mussels in the River Thames. The survey was one of the first to quantitatively evaluate freshwater mussel populations. It was conducted at a site near Reading by Christina Negus, then a postgraduate researcher from the University of Reading.</p>
<p>Her research found that freshwater mussels represent 90% of living organisms by weight on the Thames’ riverbed. The survey’s findings emphasised the role of freshwater mussels as some of the river’s key species. </p>
<p>Our survey reassessed the population of freshwater mussels along the same stretch of the river and used methods identical to those used by Negus. We found that the population of freshwater mussels has declined by almost 95% since 1964. One species, the <a href="https://freshwaterhabitats.org.uk/pond-clinic/identifying-creatures-pond/depressed-river-mussel/">depressed river mussel</a>, may have disappeared entirely from the river. </p>
<p>The results of our survey also suggest that River Thames mussels are smaller than they were at the time of the original survey. Their total size and rates of growth have fallen by 10%-35% compared to 1964.</p>
<p>We also identified the presence of an invasive species of mussel, the <a href="https://www.usgs.gov/faqs/what-are-zebra-mussels-and-why-should-we-care-about-them">zebra mussel</a>. Zebra mussels are found across Europe and North America and threaten native mussel species by settling directly on their shells, competing for food, and sometimes preventing a mussel from opening. The presence of the highly invasive Zebra mussel, which was not observed in the 1964 survey, could have contributed to the decline in the overall number of freshwater mussels recorded by our survey.</p>
<figure class="align-center ">
<img alt="A closed zebra mussel with an orange shell marked with a zebra-like pattern." src="https://images.theconversation.com/files/497643/original/file-20221128-22-n9yes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/497643/original/file-20221128-22-n9yes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/497643/original/file-20221128-22-n9yes.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/497643/original/file-20221128-22-n9yes.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/497643/original/file-20221128-22-n9yes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/497643/original/file-20221128-22-n9yes.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/497643/original/file-20221128-22-n9yes.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The survey recorded the invasive zebra mussel in the River Thames.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/zebra-mussels-invasive-species-that-has-1225419361">RLS Photo/Shutterstock</a></span>
</figcaption>
</figure>
<h2>A cleaner river</h2>
<p>Lower levels of nutrients, such as phosphate, in the river may be part of the reason why mussels are smaller and slower to grow than observed in 1964. Nutrients stimulate the growth of algae, a key source of food for mussels. Reduced nutrient content could therefore lead to lower food availability for mussels and slower growth rates as a result.</p>
<p>The Thames was heavily polluted at the time of the original survey. We spoke to Negus, who recalled having a sore throat for the entire two years she conducted her survey, a symptom she attributes to the polluted river. This implies that the size and growth rates of the freshwater mussels recorded in 1964 may have increased artificially due to nutrient pollution from human sources.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/497606/original/file-20221128-20-n56lpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A slick of green algae covering a pond." src="https://images.theconversation.com/files/497606/original/file-20221128-20-n56lpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/497606/original/file-20221128-20-n56lpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=277&fit=crop&dpr=1 600w, https://images.theconversation.com/files/497606/original/file-20221128-20-n56lpd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=277&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/497606/original/file-20221128-20-n56lpd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=277&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/497606/original/file-20221128-20-n56lpd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=348&fit=crop&dpr=1 754w, https://images.theconversation.com/files/497606/original/file-20221128-20-n56lpd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=348&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/497606/original/file-20221128-20-n56lpd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=348&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Algae is a food source for mussels.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/algal-blooms-due-over-phosphate-materials-1824637664">Manishankar Patra/Shutterstock</a></span>
</figcaption>
</figure>
<p>But since being declared “biologically dead” in 1957 due to its level of pollution, the Thames has <a href="https://www.zsl.org/natureatheart/the-state-of-the-thames-2021">recovered</a> and is now ranked among the <a href="https://www.mylondon.news/news/zone-1-news/thames-cleanest-river-world-dirty-20601885">cleanest urban rivers</a> globally. </p>
<p><a href="https://ec.europa.eu/environment/water/water-framework/info/intro_en.htm">Tighter rules</a> around the release of sewage have resulted in concentrations of phosphate in the River Thames falling considerably since the 1960s. Viewed this way, today’s smaller mussels may be indicative of the river’s return to a more “natural” state.</p>
<h2>Changing ecosystem</h2>
<p>However, the picture is more complicated than this implies. Invasive species and broader threats to habitat, such as <a href="https://www.newcivilengineer.com/latest/tideway-river-bed-dredging-begins-at-deptford-creek-19-03-2020/">dredging</a> and intensive land use along the riverbank, may also have driven the decline in what were once some of the river’s most abundant animals. So these declines sound a warning about the health of the river’s ecosystems. </p>
<p>Among the mussels experiencing the greatest declines are the <a href="https://www.iucnredlist.org/species/155667/4818080">duck mussel</a> and the <a href="https://www.iucnredlist.org/species/155543/4796089">painter’s mussel</a>, the populations of which have declined by 98.9% and 96.8% respectively. Both of these species are generally considered common and are not listed as threatened. There are no monitoring programmes or protections currently in place for these species as a result. </p>
<figure class="align-center ">
<img alt="Several of the species of mussel that are found in the Thames positioned on grass." src="https://images.theconversation.com/files/497639/original/file-20221128-14-cny4cz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/497639/original/file-20221128-14-cny4cz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=284&fit=crop&dpr=1 600w, https://images.theconversation.com/files/497639/original/file-20221128-14-cny4cz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=284&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/497639/original/file-20221128-14-cny4cz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=284&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/497639/original/file-20221128-14-cny4cz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=357&fit=crop&dpr=1 754w, https://images.theconversation.com/files/497639/original/file-20221128-14-cny4cz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=357&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/497639/original/file-20221128-14-cny4cz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=357&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Several of the freshwater mussel species found in the Thames – the painter’s mussel, the swollen river mussel, and the duck mussel.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>If our findings reflect a wider decline in the status of freshwater mussels in rivers across the UK, then we could be approaching a critical and unexpected population collapse. Such a collapse is likely to have a negative impact on freshwater ecosystems because of mussels’ role in promoting invertebrate biodiversity.</p>
<p>So while a cleaner river is positive for river biodiversity, such severe declines in these once abundant species suggest we should increase our efforts to protect these valuable yet fragile ecosystems.</p><img src="https://counter.theconversation.com/content/195402/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Isobel Ollard does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A new survey has revealed an alarming deterioration in the health of the River Thames ecosystem – but some of the recorded changes may be the result of a cleaner river.Isobel Ollard, PhD Researcher, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1920772022-11-08T19:34:30Z2022-11-08T19:34:30ZThe use of natural outdoor laboratories can reduce threats to freshwater biodiversity<figure><img src="https://images.theconversation.com/files/491462/original/file-20221024-19-6p77s4.jpg?ixlib=rb-1.1.0&rect=52%2C21%2C3432%2C1175&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Studying the impacts of climate and landscape stressors on freshwater biodiversity can only help find more strategic solutions when conducted in the messy, yet realistic, outdoor environment.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>From densely developed cities and geometric agricultural plots to the ubiquitous roadways, pipelines and power grids, an aerial view of the earth reveals our impact on our landscapes. In less populated areas, <a href="https://www.theguardian.com/environment/2021/apr/28/speed-at-which-worlds-glaciers-are-melting-has-doubled-in-20-years">unprecedented glacial melt</a> and <a href="https://www.youtube.com/watch?v=-IM57fWq8pg&ab_channel=NorthwestTerritoriesGeologicalSurvey">deep craters caused by the thawing of frozen soil and rock called permafrost megaslumps</a> give stark reminders of the ongoing climate crisis.</p>
<p>Our entire global biodiversity, from these deforested lands and glaciers to coral reefs and tiny <a href="https://www.youtube.com/watch?v=tdJUD03Pn6c&ab_channel=ChesapeakeBayFoundation">freshwater mussels</a>, <a href="https://livingplanet.panda.org/en-us/">is now in jeopardy</a>. The <a href="https://www.iucn.org/news/water/202002/emergency-recovery-plan-could-halt-catastrophic-collapse-worlds-freshwater-biodiversity">collapsing freshwater systems</a> are already affecting our health and well-being <a href="https://doi.org/10.1139/er-2015-0064">by weakening our resilience to extreme climatic events and our local economies, while also disrupting water and food security</a>. </p>
<p>These vital freshwater ecosystems are increasingly affected by various <a href="https://publications.gc.ca/collections/collection_2022/mpo-dfo/Fs97-4-3243-eng.pdf">co-occurring threats or “cumulative effects” of human actions including urbanization, agriculture, resource development and climate change</a>. However, managing these cumulative effects remains a challenge as their impacts on biodiversity highly vary depending on the specific mixture of threats and other ecological factors. </p>
<p>To address this growing need for strategic solutions for the biodiversity crisis, our team of scientists from Carleton University and Wildlife Conservation Society Canada conducted a <a href="https://doi.org/10.1007/s40823-022-00074-7">global review of over 150 studies</a> to understand the impacts of climate and landscape stressors on freshwater biodiversity in the messy, yet realistic, outdoor environments.</p>
<h2>Studying real world threats to biodiversity</h2>
<p>Studying how cumulative effects like urbanization, agriculture and climate change, or a combination of such man-made threats, influence freshwater biodiversity outside of a controlled laboratory setting can be complicated and difficult. </p>
<figure class="align-right ">
<img alt="Aerial view of mining tailings outside of Dawson City, Yukon." src="https://images.theconversation.com/files/490661/original/file-20221019-15255-tit42e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/490661/original/file-20221019-15255-tit42e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490661/original/file-20221019-15255-tit42e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490661/original/file-20221019-15255-tit42e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490661/original/file-20221019-15255-tit42e.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490661/original/file-20221019-15255-tit42e.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490661/original/file-20221019-15255-tit42e.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Human actions can influence and threaten freshwater biodiversity.</span>
<span class="attribution"><span class="source">(Alyssa Murdoch)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Climate change and land-use stressors may affect species differently depending on their surrounding environment.</p>
<p>For example, some species may benefit from warming air and waters, while others may have <a href="https://doi.org/10.1111/gcb.13028">wildly different responses to warming</a> depending on additional factors such as the level of human disturbance or the presence of an invasive species. </p>
<p>To further complicate things, other seemingly straightforward stressors, such as industrial or road development, can also be challenging to predict. </p>
<p>In fact, <a href="https://doi.org/10.1111/j.1365-2427.2011.02619.x">less human disturbance may benefit certain species</a> due to increased food availability or the exclusion of predators from the impacted area, but may eventually lead to declines with continuous additional stress. </p>
<p>To create effective on-the-ground conservation and management solutions, it is crucial to understand how these stressors influence biodiversity across varying ecosystems.</p>
<h2>Taking the lab outside</h2>
<p>Through our study, we found some examples of scientific discovery that came from outdoor laboratories — places where scientists could manipulate entire lakes or create artificial streams to mimic the real thing.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/AfOGKhPW-0A?wmode=transparent&start=36" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Scientific experiments conducted at Ontario’s Experimental Lakes Area have uncovered numerous challenging environmental issues.</span></figcaption>
</figure>
<p>The whole-lake experiments conducted in the <a href="https://www.iisd.org/ela/">Experimental Lakes Area in Ontario</a>, for instance, uncovered well-known environmental issues ranging from acid rain to the impacts of pervasive nutrient runoff into freshwater bodies. </p>
<p>In New Zealand, researchers have developed an <a href="https://vimeo.com/243219546">ExStream system</a> containing 128 miniature artificial stream systems that can be manipulated to have different conditions like warmer or cooler temperatures. </p>
<p>This world-class facility has produced ground-breaking work demonstrating how <a href="https://doi.org/10.1371/journal.pone.0049873">individual environmental stressors may combine or even interact</a> to produce unexpected impacts on freshwater biodiversity.</p>
<h2>Out of the lab and into the field</h2>
<p>The results of studies conducted in outdoor environments can be influenced by numerous factors like habitat type, the regional climate or by the presence of other species. Very little of this can be realistically controlled.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/490660/original/file-20221019-25-h6a0ka.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Guidelines for designing cumulative effects studies in two contrasting environments." src="https://images.theconversation.com/files/490660/original/file-20221019-25-h6a0ka.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/490660/original/file-20221019-25-h6a0ka.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=741&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490660/original/file-20221019-25-h6a0ka.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=741&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490660/original/file-20221019-25-h6a0ka.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=741&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490660/original/file-20221019-25-h6a0ka.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=931&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490660/original/file-20221019-25-h6a0ka.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=931&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490660/original/file-20221019-25-h6a0ka.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=931&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Different geographical areas face differing sets of major threats to biodiversity and ecological factors.</span>
<span class="attribution"><span class="source">(WCS Canada)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Different geographical areas such as remote, high-latitude regions versus more developed low-latitude areas, may have an entirely different suite of major threats to biodiversity and ecological factors to consider. </p>
<p>In our review, we found that identifying and categorizing potential study sites ranging from pseudo “control” sites, which face little to no climate and land-use stress, to more moderate and high stress areas can help develop a more strategic outdoor study. </p>
<p>This approach is similar to manipulated experimental set-ups in nature. In one such set-up, a team of scientists conducted an <a href="https://www.jstor.org/stable/44743556">extensive nationwide survey of cumulative effects</a> on stream fish in the U.S. by first identifying reference sites with relatively low human disturbance levels. This was done to support the U.S. National Fish Habitat Action Plan.</p>
<p>Another key step for scientists to strengthen their strategic outdoor study is to figure out what other environmental factors they want to measure (and possibly control for). This approach can help them understand biodiversity’s response to cumulative climate and land-use stressors in different habitats.</p>
<p>This in turn can help inform more strategic conservation strategies, benefiting the entire ecosystem. </p>
<h2>A unified way forward</h2>
<p>Today, more and more environmental managers and scientists working in academia or with governments or conservation groups are shifting their focus from single threats on individual species towards <a href="https://publications.gc.ca/site/fra/9.883883/publication.html">broader ecosystem-level approaches that incorporate cumulative effects</a>, including various human development activities.</p>
<figure class="align-center ">
<img alt="Two people standing in ankle deep water of a steam studying fish." src="https://images.theconversation.com/files/490658/original/file-20221019-18-qds5lu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/490658/original/file-20221019-18-qds5lu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/490658/original/file-20221019-18-qds5lu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/490658/original/file-20221019-18-qds5lu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/490658/original/file-20221019-18-qds5lu.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/490658/original/file-20221019-18-qds5lu.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/490658/original/file-20221019-18-qds5lu.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Monitoring programs like this fish monitoring project in Yukon could help fill in our cumulative effects knowledge gaps.</span>
<span class="attribution"><span class="source">(Alyssa Murdoch)</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>While <a href="https://www.talkfishhabitat.ca/">developing environmental policies</a> often includes new language around the need to consider cumulative effects during decision-making, putting these initiatives to practice remains challenging in many information-poor regions of the world. </p>
<p>However, there are many monitoring programs that could help fill in our cumulative effects knowledge gaps. </p>
<p>In Canada, several large-scale monitoring programs like the <a href="https://www.abmi.ca/home.html">Alberta Biodiversity Monitoring Program</a>, Ontario’s <a href="https://www.ontario.ca/page/broad-scale-monitoring-program">Broad-scale Monitoring Program</a> and the <a href="https://doi.org/10.1016/j.scitotenv.2019.133668">NSERC Canadian Lake Pulse</a> could be altered to strategically study areas with varying climate and land-use disturbance levels.</p>
<p>When we recognize the value of data from “outdoor laboratories,” we can see that it is also important to tap into all possible sources of such information, including information <a href="https://doi.org/10.1139/facets-2017-0104">gathered through Impact Assessments or land-use planning</a>. </p>
<p>Making sure this information is widely accessible can help everyone — from governments and scientists to citizens — understand potential solutions that can address the biodiversity crisis. We all need to grab an oar and pull in the same direction to address the freshwater biodiversity crisis we are in today.</p><img src="https://counter.theconversation.com/content/192077/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alyssa Murdoch is a postdoctoral fellow with Wildlife Conservation Society Canada and Carleton University. She receives funding from Mitacs Elevate, the Yukon Fish & Wildlife Enhancement Trust, and Wildlife Conservation Society Canada.</span></em></p><p class="fine-print"><em><span>Chrystal Mantyka-Pringle receives funding from Wilburforce Foundation, William and Flora Hewlett Foundation, Environment and Climate Change Canada, and Yukon Fish and Wildlife Enhancement Trust. She is affiliated with Wildlife Conservation Society Canada and the University of Saskatchewan. </span></em></p>Governments, industrial and development companies and scientists need to take a leading role in finding strategic solutions to the cumulative threats impacting our freshwater ecosystems.Alyssa Murdoch, Postdoctoral fellow, Cooke Lab, Carleton UniversityChrystal Mantyka-Pringle, Conservation Planning Biologist, Wildlife Conservation Society Canada and Adjunct Professor of Conservation Biology, University of SaskatchewanLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1870422022-11-02T17:27:05Z2022-11-02T17:27:05ZRipple effect: As global freshwater basins dry up, the threat to ecosystems and communities grows<figure><img src="https://images.theconversation.com/files/492515/original/file-20221031-15-781iqe.jpg?ixlib=rb-1.1.0&rect=14%2C85%2C1942%2C1217&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hundreds of freshwater basins across the world, including the dried-up Santa Olalla permanent freshwater lagoon, in Spain's Doñana National Park, are the most likely to experience social and ecological impacts due to freshwater use.</span> <span class="attribution"><span class="source">(Donana Biological Station/CSIC)</span></span></figcaption></figure><p>When people use freshwater beyond a physically sustainable rate, <a href="https://doi.org/10.1038/nature09440">it sets off a cascade of impacts on ecosystems, people and the planet</a>. These impacts include groundwater <a href="https://calmatters.org/environment/2021/08/california-groundwater-dry/">wells running dry</a>, fish populations becoming stranded <a href="https://hakaimagazine.com/features/what-to-do-with-fish-when-the-river-runs-dry/">before they are able to spawn</a> and <a href="https://www.euronews.com/2022/05/27/spain-s-donana-national-park-under-threat-as-groundwater-pumping-continues">protected wetland ecosystems turning into dry landscapes</a>. </p>
<p>Developments in computer models and satellites have fostered a new understanding of how freshwater is being redistributed around the planet and have made clear the central role that people play in this change. This human impact is so significant that organizations like the United States Geological Survey are <a href="https://www.usgs.gov/special-topics/water-science-school/science/water-cycle-diagrams">redrawing their water cycle diagram</a> to include the impacts of human actions. </p>
<p>Equally important to understanding how people affect freshwater availability, is understanding how people and ecosystems will respond to amplified freshwater challenges including drought, water stress and groundwater depletion. While these challenges impact localized sites, their impacts are scattered across the world. To address this <a href="https://public.wmo.int/en/media/press-release/wake-looming-water-crisis-report-warns">global water crisis</a>, global action is urgently needed. </p>
<p><a href="https://doi.org/10.1038/s41467-022-28029-w">In our recent study</a>, we identified the basins of the world that are most likely to be impacted by two central and interrelated aspects of water scarcity: <a href="https://doi.org/10.1038/srep38495">freshwater stress</a>, which occurs when the consumption of water surpasses renewable water supply, and <a href="https://doi.org/10.1038/s41586-018-0123-1">freshwater storage loss</a>, which is the depletion of freshwater in reservoirs or in groundwater bodies due to persistent overuse. </p>
<h2>Global basins impacted by water scarcity</h2>
<p>We identified <a href="https://www.nature.com/articles/s41467-022-28029-w/figures/3">168 basins</a> across the world that are the most likely to experience social and ecological impacts due to insufficient freshwater availability. These hotspot basins are found on every continent — a clear indication of the widespread, global nature of these challenges.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/492717/original/file-20221101-16-rfgko6.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A map of hotspot basins" src="https://images.theconversation.com/files/492717/original/file-20221101-16-rfgko6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/492717/original/file-20221101-16-rfgko6.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=339&fit=crop&dpr=1 600w, https://images.theconversation.com/files/492717/original/file-20221101-16-rfgko6.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=339&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/492717/original/file-20221101-16-rfgko6.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=339&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/492717/original/file-20221101-16-rfgko6.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=426&fit=crop&dpr=1 754w, https://images.theconversation.com/files/492717/original/file-20221101-16-rfgko6.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=426&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/492717/original/file-20221101-16-rfgko6.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=426&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Hotspot basins (in orange and red), which are the most likely basins to experience severe social and ecological impacts due to limited freshwater availability.</span>
<span class="attribution"><span class="source">(Xander Huggins)</span></span>
</figcaption>
</figure>
<p>To identify these hotspot basins, we assessed patterns in <a href="https://www.nature.com/articles/s41467-022-28029-w/figures/1">freshwater stress and freshwater storage trends</a> and compared these to patterns in <a href="https://www.nature.com/articles/s41467-022-28029-w/figures/2">societal ability to adapt to environmental hazards</a> and freshwater-based ecological sensitivity indicators. </p>
<p>The hotspot basins are most vulnerable largely because they are likely to experience social and ecological impacts at the same time. <a href="https://www.millenniumassessment.org/documents/document.312.aspx.pdf">People and societies depend on freshwater ecosystems</a> for drinking water, irrigation water, water filtration, erosion control, as cultural sites and for recreation. This means that ecological impacts of freshwater stress and storage loss double as social impacts through degraded ecosystem services. </p>
<h2>Managing vulnerable basins</h2>
<p>Hotspot basins are vulnerable as they are likely to face impacts such as low streamflow that harms aquatic biodiversity, reduced food security as agriculture is heavily reliant on freshwater supply, <a href="https://doi.org/10.1088/1748-9326/aa8ac0">wells running dry</a> and higher potential for <a href="https://www.worldwater.org/conflict/map/">social unrest</a>. </p>
<figure class="align-center ">
<img alt="A field irrigation sprinkler system waters rows of lettuce crops on farmland." src="https://images.theconversation.com/files/488148/original/file-20221004-11-fu8x9h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/488148/original/file-20221004-11-fu8x9h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/488148/original/file-20221004-11-fu8x9h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/488148/original/file-20221004-11-fu8x9h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/488148/original/file-20221004-11-fu8x9h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/488148/original/file-20221004-11-fu8x9h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/488148/original/file-20221004-11-fu8x9h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Declining freshwater supply can affect food security as the agriculture sector heavily relies on it.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<p>Reducing vulnerability in intertwined societal and environmental systems requires improved policy and management integration across sectors. <a href="https://www.unep.org/explore-topics/disasters-conflicts/where-we-work/sudan/what-integrated-water-resources-management">Integrated Water Resources Management</a> considers and balances social, ecological and hydrological sustainability goals by co-ordinating management across water, land and other related resources. Its <a href="https://www.sdg6monitoring.org/indicator-651/">inclusion in the United Nations Sustainable Development Goal framework</a> highlights its importance.</p>
<p>Our research found that countries including Afghanistan, Algeria, Argentina, Egypt, India, Iraq, Kazakhstan, Mexico, Somalia, Ukraine, Uzbekistan and Yemen have hotspot basins yet low implementation levels of much-needed integrated management practices. </p>
<h2>Prioritizing hotspot basins</h2>
<p>The location of hotspot basins across the world emphasizes the need for global and urgent action. Prioritizing regions based on their potential to experience social and ecological impacts can improve the effectiveness of global freshwater sustainability initiatives.</p>
<p>Our study calculated how vulnerable all the basins in the world were to the social and ecological impacts of freshwater stress and storage loss. We identified the most vulnerable basins as hotspots for global prioritization. However, while we focus on the identified hotspot basins, this does not mean that impacts cannot occur in basins with lower vulnerabilities. </p>
<figure class="align-right ">
<img alt="A dry section of a river." src="https://images.theconversation.com/files/487948/original/file-20221004-26-t92w96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/487948/original/file-20221004-26-t92w96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487948/original/file-20221004-26-t92w96.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487948/original/file-20221004-26-t92w96.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487948/original/file-20221004-26-t92w96.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1131&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487948/original/file-20221004-26-t92w96.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1131&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487948/original/file-20221004-26-t92w96.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1131&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A dry section of the Cowichan River on Vancouver Island, B.C.</span>
<span class="attribution"><span class="source">THE CANADIAN PRESS/Kevin Rothbauer</span></span>
</figcaption>
</figure>
<p>For instance, only a number of Canadian basins — all located in the prairies — are identified with moderate vulnerability in our global study. Yet, <a href="https://watershedsentinel.ca/articles/groundwater-pumping-drains-rivers-in-bc-and-globally/">dry streams on Vancouver Island</a>, <a href="https://doi.org/10.1080/07011784.2014.885677">falling groundwater levels in the Lower Mainland</a>, <a href="https://www.cbc.ca/news/canada/manitoba/drought-agriculture-disaster-rm-of-armstrong-manitoba-1.6100138">crop yields affected by drought throughout the prairies</a> and potential for <a href="https://www.cbc.ca/news/canada/nova-scotia/n-s-panel-discussing-climate-change-impacts-on-well-water-groundwater-1.6210051">salt-water intrusion along the East Coast</a> are all instances of freshwater security challenges being faced in Canada. </p>
<p>With <a href="https://thenarwhal.ca/saskatchewan-irrigation-project-explained/">massive expansion planned for irrigated agriculture in Saskatchewan</a> and increasing <a href="https://watershedwatch.ca/wp-content/uploads/2019/09/2019-09-24-Tapped-Out-RGB.pdf">water scarcity across British Columbia</a>, Canada’s current (and enviable) position of being able to act proactively on water security challenges is rapidly shrinking.</p>
<h2>Global action starts locally</h2>
<p>While our study took a global focus, the approach of mapping vulnerability to guide priority setting can be applied at other geographical scales. For instance, this analysis could be refined and applied to Canada or specific provinces or cities using globally unavailable data that may be available for these jurisdictions.</p>
<p>These insights could help boost urgency to act on the emerging national water crisis, aid the <a href="https://gwf.usask.ca/documents/meetings/water-security-for-canada/WaterSecurityForCanada_April-25-2019-2pg1.pdf">modernization of the Canada Water Act</a> or help identify communities that would benefit most from <a href="https://poliswaterproject.org/files/2019/10/POLIS-WSP2019-6e1-web.pdf">water sustainability plans</a> in British Columbia.</p>
<p>While global studies, such as ours, are helpful at systematically highlighting regions for prioritization, they do not — and should not — provide explicit solutions. Rather, in such intricate social and ecological environments, actions to reduce impacts need to be attuned to place-based social norms, cultural values, hydrological conditions and local knowledge systems. </p>
<p>Our hotspot basins can help guide such community-driven local action to help conserve freshwater resources that are most under threat and mitigate the ripple effects of these threats on people and ecosystems.</p><img src="https://counter.theconversation.com/content/187042/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Xander Huggins receives funding from the Natural Sciences and Engineering Research Council of Canada through a doctoral Canada Graduate Scholarship.</span></em></p>While we know how global changes in freshwater pose risks to humans and ecosystems, we know less about how people and ecosystems will respond to these global freshwater challenges.Xander Huggins, PhD Candidate in the Department of Civil Engineering (University of Victoria) and the Global Institute for Water Security (University of Saskatchewan), University of VictoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1908982022-09-19T11:45:55Z2022-09-19T11:45:55ZTyphoon Merbok, fueled by unusually warm Pacific Ocean, pounded Alaska’s vulnerable coastal communities at a critical time<figure><img src="https://images.theconversation.com/files/485177/original/file-20220918-52219-igrjib.jpg?ixlib=rb-1.1.0&rect=28%2C7%2C1649%2C1058&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A satellite image shows how vast the remnants of Typhoon Merbok were as the storm hit the Alaska coast.</span> <span class="attribution"><a class="source" href="https://twitter.com/NWSFairbanks/status/1571054643383533569">National Weather Service</a></span></figcaption></figure><p><em>The powerful remnants of Typhoon Merbok pounded Alaska’s western coast on Sept. 17, 2022, pushing homes off their foundations and tearing apart protective berms as water flooded communities.</em> </p>
<p><em>Storms aren’t unusual here, but Merbok built up over unusually warm water. Its <a href="https://twitter.com/NWSOPC/status/1570883906794311682">waves reached 50 feet</a> over the Bering Sea, and its storm surge sent water levels into communities at <a href="https://twitter.com/AlaskaWx/status/1571266836771270659">near record highs</a> along with near hurricane-force winds.</em></p>
<p><em>Merbok also hit during the fall subsistence harvest season, when the region’s Indigenous communities are stocking up food for the winter. Rick Thoman, a <a href="https://news.uaf.edu/expertsguide/rick-thoman/">climate scientist at the University of Alaska Fairbanks</a>, explained why the storm was unusual and the impact it’s having on coastal Alaskans.</em></p>
<h2>What stands out the most about this storm?</h2>
<p>It <a href="https://www.weather.gov/media/arh/RN-05-0003.pdf">isn’t unusual</a> for typhoons to affect some portion of Alaska, typically in the fall, but Merbok was different. </p>
<p>It <a href="https://twitter.com/Climatologist49/status/1571218582293610496/photo/1">formed in a part of the Pacific</a>, far east of Japan, where historically few typhoons form. The water there is typically too cold to support a typhoon, but right now, we have extremely warm water in the north-central Pacific. Merbok traveled right over waters that are the warmest on record going back about 100 years.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/485179/original/file-20220918-51705-mljo8r.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map shows warm waters off Japan and Russia's Kamchatka region." src="https://images.theconversation.com/files/485179/original/file-20220918-51705-mljo8r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485179/original/file-20220918-51705-mljo8r.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=396&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485179/original/file-20220918-51705-mljo8r.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=396&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485179/original/file-20220918-51705-mljo8r.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=396&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485179/original/file-20220918-51705-mljo8r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=498&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485179/original/file-20220918-51705-mljo8r.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=498&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485179/original/file-20220918-51705-mljo8r.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=498&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Sea surface temperatures show unusually warm water over the eastern Pacific Ocean, where Typhoon Merbok passed through.</span>
<span class="attribution"><a class="source" href="https://uaf-accap.org/">Alaska Center for Climate Assessment</a></span>
</figcaption>
</figure>
<p>The Western Bering Sea, closer to Russia, has been running above normal sea surface temperature since last winter. The Eastern Bering Sea – the Alaska part – has been normal to slightly cooler than normal since spring. That temperature difference in the Bering Sea helped to feed the storm and was probably part of the reason the storm intensified to the level it did. </p>
<p>When Merbok moved in to the Bering Sea, it wound up being by far the strongest storm this early in the autumn. We’ve had stronger storms, but they typically occur in October and November.</p>
<h2>Did climate change have a bearing on the storm?</h2>
<p>There’s a strong likelihood that Merbok was able to form where it did because of the <a href="https://www.ncei.noaa.gov/cag/global/time-series/globe/ocean/12/12/1880-2022">warming ocean</a>.</p>
<p>With warm ocean water, there’s <a href="https://climate.nasa.gov/ask-nasa-climate/3143/steamy-relationships-how-atmospheric-water-vapor-amplifies-earths-greenhouse-effect/">more evaporation going in the atmosphere</a>. Because all the atmospheric ingredients came together, Merbok was able to bring that very warm moist air along with it. Had the ocean been a <a href="https://www.ncei.noaa.gov/cag/global/time-series/globe/ocean/12/12/1880-2022">temperature more typical of 1960</a>, there wouldn’t have been as much moisture in the storm.</p>
<figure class="align-center ">
<img alt="Bar chart showing temperatures rising" src="https://images.theconversation.com/files/485199/original/file-20220919-62263-2t01r9.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/485199/original/file-20220919-62263-2t01r9.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/485199/original/file-20220919-62263-2t01r9.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/485199/original/file-20220919-62263-2t01r9.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/485199/original/file-20220919-62263-2t01r9.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=453&fit=crop&dpr=1 754w, https://images.theconversation.com/files/485199/original/file-20220919-62263-2t01r9.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=453&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/485199/original/file-20220919-62263-2t01r9.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=453&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Global ocean temperatures have been rising. The bars show how annual temperatures departed from the 20th century average.</span>
<span class="attribution"><a class="source" href="https://www.ncei.noaa.gov/cag/global/time-series/globe/ocean/12/12/1880-2022">NOAA</a></span>
</figcaption>
</figure>
<h2>How extreme was the flooding compared to past storms?</h2>
<p>The most outstanding feature as far as impact is the tremendous area that was damaged. All coastal regions north of Bristol Bay to just beyond the Bering Strait – hundreds of miles of coastline – had some impact. </p>
<p>At Nome – one of the very few places in western Alaska where we have long-term ocean level information – the ocean was <a href="https://twitter.com/AlaskaWx/status/1571266836771270659">10.5 feet</a> (3.2 meters) above the low-tide line on Sept. 17, 2022. That’s the highest there in nearly half a century, since the historic storm of <a href="https://doi.org/10.1080/00431672.1975.9931740">November 1974</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1571514507041595392"}"></div></p>
<p>In <a href="https://www.nytimes.com/2022/09/17/us/alaska-storm.html">Golovin</a> and <a href="https://www.ktoo.org/2022/09/17/powerful-storm-slams-western-alaska/">Newtok</a>, multiple houses floated off their foundations and are no longer habitable.</p>
<p><a href="https://savingplaces.org/stories/fighting-the-rising-tide-in-shaktoolik-alaska#.Yyd7pHbML8A">Shaktoolik</a> lost its protective berm, which is very bad news. Prior to building the berm, the community’s freshwater supply was easily inundated with saltwater. The community is now at greater risk of flooding, and even a moderate storm could inundate their fresh water supply. They can rebuild it, but how fast is a matter of time and money and resources. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1571310275739156480"}"></div></p>
<p>Another important impact is to hunting and fishing camps along the coasts. Because of the <a href="https://www.nps.gov/gis/storymaps/cascade/v1/index.html?appid=42e0af0fd1ab485596a0475d186a0919">region’s subsistence economy</a>, those camps are crucial, and they are expensive to rebuild. </p>
<p>There are no roads into these coastal communities, and <a href="https://www.ktoo.org/2022/02/21/construction-supply-chain-woes-in-rural-alaska/">getting lumber for rebuilding</a> homes and these camps is difficult. And we’re moving into typically the stormiest time of year, which makes recovery harder and planes often can’t land.</p>
<p>Lots of places also lost power and cell phone communication. The power in these remote areas is generated in the community – if that goes out there is no alternative. People lose power to their freezers, which they’re stocking up for the winter. Towns might have one grocery store, and if that can’t open or loses power, there is no other option. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1571235158342373383"}"></div></p>
<p>Winter is coming, and the time when it’s feasible to make repairs is running short. This is also the middle of hunting season, which in western Alaska is not recreation – it’s how you feed your family. These are almost all predominantly or almost exclusively Indigenous communities. Repairs are going to take time away for subsistence hunters, so all of these things are coming together at once. </p>
<h2>Does the lack of sea ice as a buffer make a difference for erosion?</h2>
<p>Historically, with storms later in the season, even a small bit of sea ice can offer protection to dampen the waves. But there’s <a href="http://nsidc.org/arcticseaicenews/2022/09/the-arctics-bald-spot/">no ice in the Bering Sea</a> at all this time of year. The full wave action pounds right to the beach. </p>
<p>As sea ice <a href="https://climate.nasa.gov/vital-signs/arctic-sea-ice/">declines with warming global temperatures</a>, communities will see more damage from storms later in the year, too.</p>
<h2>Are there lessons from this storm for Alaska?</h2>
<p>As bad as this storm was, and it was very bad, others will be coming. This is a stormy part of the world, and state and federal governments need to do a better job of communicating risks and helping communities and tribes ahead of time. </p>
<p>That might mean evacuating vulnerable people. Because if you wait until it’s certain that there’s a problem, it’s too late. Almost all of these communities are isolated. </p>
<p>I would say this is a classic case of large-scale weather models showing a general idea of the risk far in advance, but it takes longer to respond for isolated communities like those in rural Alaska. By Sept. 12, <a href="https://twitter.com/Climatologist49/status/1571218582293610496">Merbok’s storm track was clear</a>, but if communities aren’t briefed until a day or two days before the storm, there isn’t enough time for them to fully prepare.</p><img src="https://counter.theconversation.com/content/190898/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Rick Thoman does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Most of the flooded communities are Indigenous and rely on subsistence hunting that residents would normally be doing right now. Recovering from the damage will make that harder.Rick Thoman, Alaska Climate Specialist, University of Alaska FairbanksLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1841152022-08-02T17:07:43Z2022-08-02T17:07:43ZFish passes can reconnect species with habitats blocked by dams – here’s how they work<p>Over one million dams and <a href="https://theconversation.com/culverts-the-major-threat-to-fish-youve-probably-never-heard-of-143629">culverts</a> (tunnels that encircle rivers passing under roads) block the movements of fish and other wildlife in Europe. Scientists <a href="https://amber.international/stream-fragmentation-in-great-britain/">estimate</a> that less than 1% of catchments in the UK are free of obstruction. A <a href="https://worldfishmigrationfoundation.com/wp-content/uploads/2020/07/LPI_report_2020.pdf">report</a> released in 2020 showed the effect this trend is having worldwide: a more than 75% decline in the abundance of 247 migratory fish species globally since 1970. </p>
<p><a href="https://youtu.be/RuxBMBEAnJk">Brown trout</a>, for example, must swim upriver into streams to spawn. Adult <a href="https://www.nationalgeographic.com/animals/fish/facts/european-eel">European eels</a> meanwhile need to make their way downriver and out to <a href="https://theconversation.com/satellite-tagged-eels-are-leading-us-towards-their-mysterious-birthplace-66594">sea</a> to do the same. Even small dams like weirs that are a metre tall can prevent fish from swimming upstream because they are higher than most fish can jump. </p>
<p>Suitable spawning areas aren’t found everywhere in a river: every fish species <a href="https://www.frontiersin.org/articles/10.3389/fevo.2019.00286/full">has its own needs</a>. If a dam prohibits fish from reaching those habitats, the shortfall in offspring can cause populations to decline. Species <a href="https://theconversation.com/habitat-loss-doesnt-just-affect-species-it-impacts-networks-of-ecological-relationships-117687">living on the edge</a> of suitable habitats are more vulnerable to droughts and pollution and are therefore at greater risk of extinction.</p>
<p>One solution is to <a href="https://twitter.com/SCRiversTrust/status/1545052431620313094?cxt=HHwWjMCooYTAkPEqAAAA">remove dams</a>. The EU <a href="https://ec.europa.eu/commission/presscorner/detail/en/ip_22_3746">plans</a> to reconnect at least 25,000km of river across the continent by 2030, restoring the pathways migratory fish take to reproduce or feed. Completely removing a dam isn’t always possible, though, particularly where they are still used to help boats navigate. Instead, fish passes – also called fishways or ladders – can be built alongside dams to help fish <a href="https://worcesterobserver.co.uk/news/first-major-fish-pass-unlocked-by-river-severn-conservation-project/">swim up and around</a>. So how do fish passes work – and what can they do to help river ecosystems recover? </p>
<h2>Go, fish!</h2>
<p>The River Severn is the UK’s longest. Like the Mississippi in the US, the Severn has a <a href="https://www.teachengineering.org/lessons/view/cub_dams_lesson03">lock and dam</a> system on its main stem. This was built in the mid-19th century to help barges move from one section of the river to another, and is still used today. Dams raise the water level behind them and locks (giant gates) open and close to raise boats up and over.</p>
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<p>Damming caused populations of <a href="https://canalrivertrust.org.uk/enjoy-the-waterways/fishing/caring-for-our-fish/freshwater-fish-species/rare-and-protected-fish/twaite-shad">Twaite shad</a> – a silvery, herring-like fish which must move up and down the Severn to feed, grow and reproduce – to crash almost overnight. Today, it remains one of the country’s <a href="https://www.youtube.com/watch?v=YX9Pc197z44">rarest species</a>.</p>
<p><a href="https://www.unlockingthesevern.co.uk/about-this-project/">The Severn Rivers Trust</a> and partners set out to help the Twaite shad reach its historical spawning habitat upriver. Scientists <a href="https://www.unlockingthesevern.co.uk/2021/03/08/unlocking-the-secrets-of-how-fish-move-within-the-uks-longest-river/">tracked</a> the fish returning to the Severn from the sea to spawn and found that the Diglis weir near Worcester was blocking their passage. Just months after the <a href="https://youtu.be/YX9Pc197z44">largest fish pass</a> in England opened in May 2021, Twaite shad were <a href="https://youtu.be/yq06qWnH90M">recorded</a> making their way upstream and beyond the locks and dams for the first time in over a century.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/475855/original/file-20220725-19-unq819.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An aerial view of a river with a weir and a stone passage bypassing it." src="https://images.theconversation.com/files/475855/original/file-20220725-19-unq819.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/475855/original/file-20220725-19-unq819.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/475855/original/file-20220725-19-unq819.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/475855/original/file-20220725-19-unq819.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/475855/original/file-20220725-19-unq819.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/475855/original/file-20220725-19-unq819.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/475855/original/file-20220725-19-unq819.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Diglis Weir with the fish pass visible to its left.</span>
<span class="attribution"><span class="source">Skynique/Severn Rivers Trust</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Fish passes come in <a href="https://theconstructor.org/water-resources/types-fish-ladders-fishways/33911/">different designs and sizes</a>, but all are supposed to allow fish to ascend rivers through lower gradient channels or smaller steps around the side of a dam they cannot swim or jump over. Fish swimming upriver must find a narrow entrance to the pass, and the water flowing out of it is often the clue they need. Just like the river, water flows from upstream to downstream in a fish pass. If the flow is too gentle for most fish to notice or it’s too fast or turbulent for them to swim up it, the pass will either be used by some species or none at all. </p>
<p>Fish passes tend to have small, subdivided sections that act as areas for fish to rest during their journey too. The incline, the number of resting places and the flow of water both inside and at the entrance are all important for determining whether fish use the pass and if they can make it upriver.</p>
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<p>The fish pass at Diglis weir was designed for Twaite shad, which are not strong swimmers or leapers. A fish pass that this species can traverse will probably allow fish of <a href="https://www.youtube.com/watch?v=z_FO0R48d3Y&list=PL5tw6FzDfCrmQ4fk3ATD0-JFq_k8h5Z9a">various sizes and swimming abilities</a> to make their way upriver too. Not all fish passes are designed to accommodate weaker swimmers, however. Globally, fish passes have largely been built to <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/faf.12258">benefit</a> a single species or group, particularly those that are economically important, like salmon.</p>
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<p>To begin to reverse the plunge in migratory fish populations, countries should build fish passes and remove dams in ways which benefit the greatest number of species. This will require governments establishing appropriate design standards and making it a national priority to reconnect their many disjointed rivers.</p><img src="https://counter.theconversation.com/content/184115/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Stephanie Januchowski-Hartley receives funding from the Welsh government and the European Regional Development Fund. </span></em></p><p class="fine-print"><em><span>Virgilio Hermoso receives funding from the Junta de Andalucia through an Emergia contract. </span></em></p>Migratory fish populations have collapsed worldwide in the last 50 years.Stephanie Januchowski-Hartley, Sêr Cymru Research Fellow in Environmental Sciences, Swansea UniversityVirgilio Hermoso, Investigador distinguido, Universidad de SevillaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1854252022-07-05T13:37:46Z2022-07-05T13:37:46ZSouth Africa’s sandfish are on the brink of extinction: how farmers are helping rescue them<figure><img src="https://images.theconversation.com/files/471579/original/file-20220629-14-d4f8yo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sandfish migrate to the Biedouw River to spawn. They must swim through fences and over rocks, which takes a toll on them.</span> <span class="attribution"><span class="source">Jeremy Shelton</span></span></figcaption></figure><p><a href="https://www.youtube.com/watch?v=jM4jNpvemBw&t=1s">Sandfish</a> are migratory freshwater fish found only in South Africa that can grow to over half a metre in length. They sport a pronounced downturned mouth which is used to graze algae off rocks and to grub in mud and sand on the stream bed. </p>
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<figcaption><span class="caption">Sandfish: conserving one of South Africa’s most threatened large-bodied fish.</span></figcaption>
</figure>
<p>As one of the largest grazers in South Africa’s Doring River system, sandfish keep the rivers clean and the food web balanced. They also act as an <a href="https://www.worldatlas.com/articles/what-is-an-umbrella-species.html">umbrella species</a> – protecting them indirectly protects river ecosystems and other species that inhabit them. That’s by virtue of their migratory life cycle: sandfish move over long distances of river at different life stages. To thrive, they need healthy, connected rivers that hold water year-round and don’t harbour alien species. </p>
<p>Unfortunately, their migratory life cycle also makes them particularly vulnerable to human-linked impacts. Sandfish were once abundant and widespread across the Olifants and Doring River systems, but have recently disappeared from the Olifants. Their numbers in the Doring are in sharp decline.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/471351/original/file-20220628-12-ja8n83.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map with red and blue lines showing sandfish range." src="https://images.theconversation.com/files/471351/original/file-20220628-12-ja8n83.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/471351/original/file-20220628-12-ja8n83.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=704&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471351/original/file-20220628-12-ja8n83.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=704&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471351/original/file-20220628-12-ja8n83.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=704&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471351/original/file-20220628-12-ja8n83.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=884&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471351/original/file-20220628-12-ja8n83.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=884&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471351/original/file-20220628-12-ja8n83.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=884&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Map of the sandfish’s past and current range.</span>
<span class="attribution"><span class="source">Dr Bruce Paxton</span></span>
</figcaption>
</figure>
<p>We published <a href="https://onlinelibrary.wiley.com/doi/10.1002/aqc.3785?af=R">a study</a> showing that sandfish numbers in a critical tributary had declined significantly over just five years. Between 2013 and 2018, rangers from the Oorlogskloof Nature Reserve in the Northern Cape province surveyed the fish in the Oorlogskloof River. The results were sobering: a population decline of 92.6% by 2018, led by a 99.6% decrease in numbers of young sandfish. </p>
<p>Catastrophic unseasonal flows due to climate change during the 2013 spawning season likely catalysed this decline. The long <a href="https://onlinelibrary.wiley.com/doi/10.1002/aqc.3785?af=R">drought</a> that followed prevented population recovery. Adding to the problem was the presence of non-native black bass and bluegill sunfish. Where these were found, sandfish were all but absent, effectively isolating the Oorlogskloof sandfish population from those in the Doring River and creating a population sink – a low quality habitat which only contributes to a population’s decline.</p>
<p>These conditions, ubiquitous throughout the sandfish’s remaining range, have resulted in bringing the species to the brink of extinction.</p>
<p>This sort of knowledge is invaluable in focusing South Africa’s limited freshwater conservation resources where they are needed most.</p>
<h2>Threats and sanctuaries</h2>
<p>The historical range of the sandfish has more than halved in the last century. This is the result of decades of predation by introduced non-native fishes, the construction of dams that block upstream spawning migrations, extreme climatic events, and rivers that are drying due to climate change, thirsty alien plants, and the excessive withdrawal of water to supply agriculture and towns in arid regions. </p>
<p>The biggest worry is the lack of juvenile and subadult sandfish in the Doring River. It indicates an ageing population with few, if any, young sandfish surviving the precarious early life stages.</p>
<p>In 2013, a colleague accidentally stumbled on some tiny sandfish in the Doring River and discovered that they were still spawning despite the odds.</p>
<p>It catalysed the first sandfish conservation efforts, which were followed in 2018 by the Saving Sandfish Project. The goal was to better understand the most pressing threats to the sandfish and restore the species to sustainable numbers.</p>
<p>The sandfish has an impressive spawning strategy. It migrates dozens (perhaps even hundreds) of kilometres each year to reach its tributary spawning grounds. Protecting the species therefore requires collaboration with landowners whose farms and lands are crossed by the rivers that the sandfish inhabit.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471580/original/file-20220629-11-cwh89b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A fish in murky water." src="https://images.theconversation.com/files/471580/original/file-20220629-11-cwh89b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471580/original/file-20220629-11-cwh89b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471580/original/file-20220629-11-cwh89b.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471580/original/file-20220629-11-cwh89b.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471580/original/file-20220629-11-cwh89b.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471580/original/file-20220629-11-cwh89b.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471580/original/file-20220629-11-cwh89b.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Non-native species like bass have displaced native fish from most of the Doring River through predation.</span>
<span class="attribution"><span class="source">Jeremy Shelton</span></span>
</figcaption>
</figure>
<p>Since the project’s inception, six sets of landowners in the Doring River catchment have transformed their off-stream farm dams into “sandfish sanctuaries”. The safe stop-over habitats for juvenile sandfish are free of alien fish that would eat them. Tributaries that once provided nurseries for young sandfish now dry up completely each year by the end of summer, so these fish are rescued en masse and relocated to the sanctuary dams – a vital step for sandfish to complete their life cycle. </p>
<p>Once sandfish reach a predator-proof size of around 20cm, they are released back into the wild. They are tagged to allow for monitoring of how many survive and return to spawn in later years. The first release took place in 2021, so data from this year’s spawning migration will give us an indication of whether our efforts have been successful.</p>
<h2>Working with farmers</h2>
<p>In addition to providing sanctuary dams, landowners help to transport rescued sandfish, replace old in-stream fencing with sandfish-friendly fencing, provide accommodation for scientists, and even help with river monitoring.</p>
<p>The project’s approach has been unusual in partnering with farmers who directly influence the rivers. Several fruit and livestock farmers in the Biedouw River valley take water out of the river for irrigation. The conservation project recognises that farming is an equally important part of the landscape and that it is only through collaboration that progress is possible for the mutual benefit of biodiversity and people.</p>
<p>All the stakeholders in the project, be they goat farmers, guest farm owners, or nature reserve management staff, are heavily invested in the outcome of the conservation efforts.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/471583/original/file-20220629-18-hm5y9o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="People working in a body of water with buckets." src="https://images.theconversation.com/files/471583/original/file-20220629-18-hm5y9o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/471583/original/file-20220629-18-hm5y9o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/471583/original/file-20220629-18-hm5y9o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/471583/original/file-20220629-18-hm5y9o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/471583/original/file-20220629-18-hm5y9o.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/471583/original/file-20220629-18-hm5y9o.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/471583/original/file-20220629-18-hm5y9o.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Collecting 10-month-old bass-proof sandfish from the dam on Enjo Nature farm for release back into the wild.</span>
<span class="attribution"><span class="source">Dr Otto Whitehead</span></span>
</figcaption>
</figure>
<h2>Moving forward</h2>
<p>While still in its infancy, this conservation project can already count a series of successes. Thousands of sandfish have been successfully reared in off-stream farm dams, creating source populations for reintroductions for years to come. Over 1,200 nursery-reared sandfish have been released back into the wild. Countless relationships have been forged with landowners, farmworkers and other stakeholders in the Doring River catchment which will ensure the sustainability of the project into the future.</p>
<p>Perhaps most importantly, the Saving Sandfish project has created awareness of the problems of river conservation in this arid region. And it acts as a rallying point for a community of diverse land-users who share a common goal: to protect the natural environment for the benefit of all.</p><img src="https://counter.theconversation.com/content/185425/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cecilia Cerrilla receives funding from the University of Cape Town and the Rufford Foundation. </span></em></p><p class="fine-print"><em><span>The Saving Sandfish project is funded by the National Geographic Society (Co-funded by the IUCN Species Survival Commission), IUCN Save Our Species (Co-funded by the European Union), The Rufford Foundation, The Mohamed Bin Zayed Species Conservation Fund, the Federation of Southern African Flyfishers (FOSAF), Mount Ceder, Investec, Caleo Capital, Bushmans Kloof and the Ford Wildlife Foundation.</span></em></p><p class="fine-print"><em><span>Charles L. Griffiths does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Sandfish keep the rivers clean and the food web balanced but their numbers are declining. Farmers are helping to lift these numbers.Cecilia Cerrilla, PhD student, University of Cape TownCharles L. Griffiths, Emeritus Professor, University of Cape TownLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1838062022-05-29T19:54:24Z2022-05-29T19:54:24Z11,000 litres of water to make one litre of milk? New questions about the freshwater impact of NZ dairy farming<figure><img src="https://images.theconversation.com/files/465427/original/file-20220526-13-lehs4k.jpg?ixlib=rb-1.1.0&rect=22%2C14%2C4898%2C3231&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Water scarcity and water pollution are increasingly <a href="https://www.nature.com/articles/s41545-019-0039-9#:%7E:text=At%20present%2C%20slightly%20less%20than,least%201%20month%20each%20year.&text=According%20to%2C3%20the%20number,52%25%20of%20the%20global%20population">critical global issues</a>. Water <a href="https://www.nature.com/articles/nature21403">scarcity is driven</a> not only by shortages of water, but also by rendering water unusable through pollution. New Zealand is no exception to these trends.</p>
<p>Demand for water has rapidly increased, and New Zealand now has the <a href="https://www.oecd.org/newzealand/oecd-environmental-performance-reviews-new-zealand-2017-9789264268203-en.htm">highest per capita</a> take of water for agriculture among OECD countries. Regulatory failures have also led to <a href="https://www.sbc.org.nz/__data/assets/pdf_file/0005/99419/A-Best-Use-Solution-for-NZs-Water-Problems.pdf">over-allocation</a> of many ground and surface water resources.</p>
<p>Some water sources are also well on the way to being unusable. Over the past few decades, nutrient and sediment emissions into waterways <a href="https://www.oecd.org/newzealand/oecd-environmental-performance-reviews-new-zealand-2017-9789264268203-en.htm">have increased</a>, driven by agricultural and horticultural intensification.</p>
<p>Much is made of the environmental benefits of New Zealand’s “grass-fed” dairy systems. But a major downside of high-intensity outdoor farming systems is the nitrate leaching from animal waste and synthetic fertilisers that contaminates fresh water.</p>
<h2>Milk’s grey water footprint</h2>
<p>Our <a href="https://www.tandfonline.com/doi/abs/10.1080/14486563.2022.2068685?journalCode=tjem20">new paper</a> focuses on nitrate pollution in Canterbury. We comprehensively quantify, for the first time, the nitrate “grey water” footprint of milk production in the region.</p>
<p>A <a href="https://waterfootprint.org/media/downloads/TheWaterFootprintAssessmentManual_2.pdf">water footprint</a> (WF) is a measure of the volume of fresh water used to produce a given mass or volume of product (in this case, milk).</p>
<p>It’s made up of both “consumptive” and “degradative” components. The consumption component is rainwater (green WF) and groundwater or surface water (blue WF) used in irrigation. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/air-of-compromise-nzs-emissions-reduction-plan-reveals-a-climate-budget-thats-long-on-planning-short-on-strategy-181478">Air of compromise: NZ's Emissions Reduction Plan reveals a climate budget that’s long on planning, short on strategy</a>
</strong>
</em>
</p>
<hr>
<p><a href="https://waterfootprint.org/media/downloads/Report65-GreyWaterFootprint-Guidelines_1.pdf">Grey water</a> is the degradative part – the volume of water needed to dilute the pollutants produced to the extent the receiving water remains above water quality standards.</p>
<p>Most water footprint studies of food systems highlight the consumptive water component and often neglect the degradative component. However, we found Canterbury’s pasture-based systems mean grey water is the biggest component.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/465446/original/file-20220526-24-7k1e0b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/465446/original/file-20220526-24-7k1e0b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/465446/original/file-20220526-24-7k1e0b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/465446/original/file-20220526-24-7k1e0b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/465446/original/file-20220526-24-7k1e0b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/465446/original/file-20220526-24-7k1e0b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/465446/original/file-20220526-24-7k1e0b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Too many cows? Recalculating the impact of milk production.</span>
<span class="attribution"><span class="source">Getty Images</span></span>
</figcaption>
</figure>
<h2>Standards and thresholds</h2>
<p>Our analysis found the nitrate grey water footprint for Canterbury ranged from 433 to 11,110 litres of water per litre of milk, depending on the water standards applied and their nitrate thresholds. </p>
<p>The 11,110 litre figure is to meet the Australasian <a href="https://environment.govt.nz/publications/australian-and-new-zealand-guidelines-for-fresh-and-marine-water-quality/">guideline level</a> to protect aquatic ecosystems, and the 433 litre figure is to meet current drinking water limits. </p>
<p>(Drinking water having lower limits may seem counter-intuitive, but the limit is based on 70-year-old research that has been superseded without legislation catching up.)</p>
<p>The larger footprint is higher than many estimates for global milk production. It reveals that footprints are very dependent on the inputs (such as feed and fertiliser) included in analyses and water quality standards.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/if-we-want-to-improve-nzs-freshwater-quality-first-we-need-to-improve-the-quality-of-our-democracy-159322">If we want to improve NZ’s freshwater quality, first we need to improve the quality of our democracy</a>
</strong>
</em>
</p>
<hr>
<p>A previous <a href="https://doi.org/10.1016/j.agsy.2012.03.006">dairy water footprint study</a> in Canterbury gave a grey water footprint of about 400 litres of water to make a litre of milk. However, it used the New Zealand drinking water standard for nitrate-nitrogen (nitrogen present in the form of nitrate ion) of 11.3 milligrams per litre (mg/l). </p>
<p>This vastly underestimates the problem. <a href="https://waterfootprint.org/media/downloads/TheWaterFootprintAssessmentManual_2.pdf">The Water Footprint Assessment Manual</a>, which sets a global standard, stipulates the concentration of pollutants should meet “prevailing” freshwater quality standards. </p>
<p>In New Zealand, the National Policy Statement for Freshwater Management sets a bottom line for <a href="https://environment.govt.nz/assets/Publications/Files/national-policy-statement-for-freshwater-management-2020.pdf">nitrate-nitrogen of 2.4mg/l</a>, much lower than the level for drinking water.</p>
<p>Our analysis – based on prevailing freshwater quality standards – shows the production of one litre of milk in Canterbury requires about 11,000 litres of water to meet the <a href="https://www.tandfonline.com/doi/full/10.1080/14486563.2022.2068685?journalCode=tjem20">ecosystem health standards</a>.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1420184973584199680"}"></div></p>
<h2>12-fold reduction needed</h2>
<p>The large footprint for milk in Canterbury indicates just how far the capacity of the environment has been overshot. To maintain that level of production and have healthy water would require either 12 times more rainfall in the region or a 12-fold reduction in cows.</p>
<p>Dairy farming at current levels of intensity is clearly unsustainable. We know <a href="https://environment.govt.nz/publications/environment-aotearoa-2019/">85% of waterways</a> in pasture catchments, which make up half the country’s waterways (measured by length), exceed nitrate-nitrogen guideline values for healthy ecosystems.</p>
<p>Evidence is also <a href="https://pubmed.ncbi.nlm.nih.gov/29435982/">emerging</a> of the direct <a href="https://www.sciencedirect.com/science/article/pii/S001393511930218X">human health</a> effects (colon cancer and birth defects) of nitrate in drinking water. Extensive dairy farming in Canterbury is already leading to significant pollution of the region’s groundwater, much of which is used for drinking water.</p>
<p>Current practices also threaten the market perception of the sustainability of New Zealand’s dairy industry and its products. The “grass-fed” marketing line overlooks the huge amounts of fossil-fuel-derived fertiliser used to make the extra grass that supports New Zealand’s very high animal stock rates. </p>
<p>Also overlooked is the palm kernel expeller (PKE) fed directly to cows. New Zealand is the <a href="https://www.indexmundi.com/agriculture/?commodity=palm-kernel-meal&graph=imports">biggest importer globally</a> of this byproduct of palm oil production.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/without-a-better-plan-new-zealand-risks-sleepwalking-into-a-biodiversity-extinction-crisis-182279">Without a better plan, New Zealand risks sleepwalking into a biodiversity extinction crisis</a>
</strong>
</em>
</p>
<hr>
<h2>The synthetic fertiliser problem</h2>
<p>Growing use of synthetic nitrogen fertiliser has helped dramatically increase nitrate levels and the water pollution problems New Zealand faces.</p>
<p>Until the 1990s, reactive nitrogen (a term used for a variety of nitrogen compounds that support growth) in pastures was predominantly obtained through nitrogen-fixing clover plants. But synthetic nitrogen fertiliser from fossil fuels displaced natural systems and drove intensification.</p>
<p>Globally, synthetic nitrogen production has now <a href="https://www.nature.com/articles/ngeo325">eclipsed</a> all that produced by natural systems. This disruption of the nitrogen cycle seriously threatens global human sustainability, not only through its impacts on the climate, but also through localised impacts on fresh water.</p>
<p>The European Science Foundation <a href="https://www.cambridge.org/core/books/abs/european-nitrogen-assessment/summary-for-policy-makers/8C71929358438A6F1BDBEADB38E44E67">described</a> the industrial-scale production of synthetic nitrogen as “perhaps the greatest single experiment in global geo-engineering that humans have ever made”.</p>
<p>It is clear that water is becoming a defining political and economic issue. Changing attitudes to its quality and accessibility depends on accurate information – including how water is used to dilute agricultural waste.</p><img src="https://counter.theconversation.com/content/183806/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mike Joy is affiliated with The Environmental Law Initiative (ELI). </span></em></p>A new study of dairying in Canterbury shows previous estimates vastly underestimate the impact of intensive farming. A 12-fold reduction in cow numbers could be needed to meet safe water standards.Mike Joy, Senior Researcher; Institute for Governance and Policy Studies, Te Herenga Waka — Victoria University of WellingtonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1807962022-04-21T09:50:32Z2022-04-21T09:50:32ZNigeria’s pristine freshwater ecosystems need protection before they are lost<figure><img src="https://images.theconversation.com/files/457952/original/file-20220413-24-hya8l8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/arinta-waterfall-royalty-free-image/1327194505?adppopup=true">Fela Sanu via GettyImages </a></span></figcaption></figure><p>As human populations grow, pure freshwater systems are becoming <a href="https://onlinelibrary.wiley.com/doi/10.1002/aqc.3778">rare</a> around the world. Urbanisation and infrastructure development have had <a href="https://www.fni.no/publications/the-anthropocene-is-functionally-and-stratigraphically-distinct-from-the-holocene">an impact</a> on the natural environment in African countries, as elsewhere. Many species have become <a href="https://www.sciencedirect.com/science/article/abs/pii/S0147651319314848?via%3Dihub">extinct</a>.</p>
<p>In Nigeria, various environmental pressures have <a href="https://www.ajol.info/index.php/wajae/article/view/108003">jeopardised</a> freshwater biodiversity in recent years. Undisturbed freshwater systems have become scarce, as <a href="https://www.sciencedirect.com/science/article/abs/pii/S0147651319314848?via%3Dihub">human activity</a> has destroyed many rivers, lakes and streams. </p>
<p>Cutting down trees, using water for domestic and industrial purposes, farming on river banks, dumping garbage and washing are some of the activities that <a href="https://www.sciencedirect.com/science/article/abs/pii/S0147651319314848?via%3Dihub">contribute</a> to reducing freshwater biodiversity. </p>
<p><a href="https://onlinelibrary.wiley.com/doi/10.1002/aqc.3778?af=R">Studies</a> have found that the animals in Nigeria’s freshwater ecosystems are mostly species that indicate low or moderate water quality. In the waters studied, there are fewer species that indicate excellent water quality. Larvae of non-biting midges, soldier flies and hover flies are examples of <a href="https://www.sciencedirect.com/science/article/abs/pii/0043135483901884">species that indicate</a> poor water quality. But biological indicators of excellent water quality, such as mayflies, stoneflies and caddisflies, are <a href="https://onlinelibrary.wiley.com/doi/10.1002/aqc.3778">frequently underrepresented</a>. </p>
<p>My research group recently <a href="https://onlinelibrary.wiley.com/doi/10.1002/aqc.3778">conducted an ecological study</a> of the freshwater systems of three waterfalls in Nigeria’s remote regions. They are all far from human settlement and are situated in Nigeria’s different vegetation and geographical zones. Our findings revealed that the streams had exceptional biological water quality, which is unusual in Nigeria.</p>
<p>It’s important to protect these places because pristine freshwater ecosystems are becoming rarer globally.</p>
<h2>Freshwater systems in Nigeria</h2>
<p>Three insect orders are frequently employed as <a href="https://www.sciencedirect.com/science/article/abs/pii/S1470160X13000459">indicators</a> of high-quality freshwater habitats. </p>
<p>Ephemeroptera (commonly known as mayflies), Plecoptera (stoneflies), and Trichoptera (caddisflies) <a href="https://www.sciencedirect.com/science/article/abs/pii/S1470160X13000459">make up</a> the indicator. In most cases globally, pristine freshwater systems have no fewer than <a href="https://pubs.usgs.gov/fs/2002/0118/fs20020118.pdf">10 species</a> of the three insect groups. The three insect groups are used as the benchmark for identifying top-quality sites. Such sites should support a wide range of species of the three insect orders. The higher the indicator value, the richer a freshwater system is in terms of biological diversity.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/we-found-a-rare-insect-at-an-unspoilt-stream-in-nigeria-sign-of-a-need-to-explore-and-protect-171966">We found a rare insect at an unspoilt stream in Nigeria – sign of a need to explore and protect</a>
</strong>
</em>
</p>
<hr>
<p>At Arinta Waterfalls in Ekiti State, southwest Nigeria, we discovered 19 species indicating excellent water quality. At Ekor Waterfalls in Cross River State, southern Nigeria we found 13. We discovered 29 indicator species at Oowu Waterfalls in Kwara State, north-central Nigeria. These records exceeded <a href="https://pubs.usgs.gov/fs/2002/0118/fs20020118.pdf">the benchmark</a> for freshwater systems with excellent ecological integrity. In Nigeria it’s rare to exceed this benchmark.</p>
<p>Our findings also revealed that the three sites had very high conservation value. An index value of not less than 20 is the standard. At all three locations, the index was greater than 20. The conservation index has been applied in Britain and Ireland for identifying freshwater systems of conservation importance. Its application has been <a href="https://vdoc.pub/documents/conservation-monitoring-in-freshwater-habitats-a-practical-guide-and-case-studies-30fnpn5nj8v0">recommended</a> for international use. This study is the first application of the index in tropical Africa. </p>
<p>Freshwater environments with high conservation value have great promise for both terrestrial and freshwater biological diversity. They also bode well for human survival. Many insects <a href="https://link.springer.com/article/10.1007/s00027-022-00850-x">require clean water</a> to survive as larvae before maturing into adults and moving to forested areas near water. They become part of the food chain in these forests, passing their chemical energy to other animals. The larval insects are also <a href="https://www.sciencedirect.com/science/article/abs/pii/S0377840115000802?via%3Dihub">essential food</a> for fishes. </p>
<p>When present in significant numbers, the indicator group is a <a href="https://onlinelibrary.wiley.com/doi/10.1111/fwb.12211">clear signal</a> of natural freshwater with preserved riparian forests – little <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5584830/">altered</a> by human activity. Such freshwater systems <a href="https://www.sciencedirect.com/science/article/abs/pii/S1470160X13000459?via%3Dihub">imply</a> a high level of naturalness and make an excellent ecotourism destination.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/destroying-nigerias-riverside-forests-is-bad-for-the-freshwater-ecosystem-132022">Destroying Nigeria's riverside forests is bad for the freshwater ecosystem</a>
</strong>
</em>
</p>
<hr>
<h2>Potential for ecotourism</h2>
<p>Apart from their biodiversity value, the three locations we studied have the potential to become ecotourism destinations in Nigeria. At present, ecotourists under-appreciate the sites, and ecologists under-report them. Only the Arinta Waterfalls site is under the close supervision of Ekiti State Tourism Board. The Abia village community in Cross River State is responsible for managing the Ekor Waterfalls site. Though the Kwara State Government recognises the Oowu Waterfalls as an ecotourism site, poor management and a poor road network leading to the site indicate that it is neglected. </p>
<p>Among the three, Oowu Waterfalls is <a href="https://www.sciendo.com/article/10.1515/agta-2018-0002">remarkable</a> for being the steepest and one of the highest waterfalls in West Africa.</p>
<p>The absence of well-organised management at the locations foreshadows a serious threat to these exceptional freshwater systems. There are already symptoms of uncontrolled human activity such as deforestation and tourist garbage dumping, albeit on a small scale. </p>
<p>Concerned governments should devise ways to protect and conserve these excellent streams. <a href="https://onlinelibrary.wiley.com/doi/10.1002/aqc.1010">The goal</a> is to identify freshwater habitats of high ecological integrity for conservation before they are spoilt by human activities. Protecting biodiversity will also meet other human needs like tourism, agriculture and mining.</p>
<p>The authorities need plant and animal ecologists to take an inventory of the sites’ terrestrial and aquatic biodiversity. This baseline data is critical to draw up conservation plans, monitor naturalness and protect sites during future infrastructure developments.</p><img src="https://counter.theconversation.com/content/180796/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emmanuel O. Akindele works for Obafemi Awolowo University, Ile-Ife, Nigeria. He receives funding from the British Ecological Society. </span></em></p>Nigeria should urgently protect three freshwater ecosystems as these undisturbed environments are becoming rare globally.Emmanuel O. Akindele, Senior Lecturer, Obafemi Awolowo UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1796202022-03-21T18:09:53Z2022-03-21T18:09:53ZGroundwater: depleting reserves must be protected around the world<figure><img src="https://images.theconversation.com/files/453335/original/file-20220321-21-1hj00o7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A well brings groundwater to the surface at an oasis in Egypt. </span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/water_alternatives/36424070724/in/photolist-26if5jE-XuETeo-7PABtL">Water Alternatives Photos</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>Though water is central to our everyday lives and indeed life itself, we often mark World Water Day on March 22 not by reminding ourselves of all that water brings, but of the consequences of its absence or contamination. </p>
<p>As the American polymath <a href="https://archive.org/details/privatelifeoflat00franrich/mode/2up?ref=ol&view=theater">Benjamin Franklin noted</a>, “when the well runs dry, we (shall) know the worth of water”. This direct reference to groundwater, the water flowing through the pores and cracks in rocks beneath our feet, is fitting as the theme of this year’s water day is <a href="https://www.worldwaterday.org/">Groundwater: Making the Invisible, Visible</a>. </p>
<p>Groundwater is our planet’s invaluable natural store of freshwater but it is woefully neglected. It differs from the water running off into rivers, lakes and wetlands as this underground flow derives from precipitation that occurred years, decades or even millennia ago. Much of the estimated <a href="http://www.doi.org/10.1038/ngeo2590">23 million km³</a> of groundwater in the upper 2 km of the Earth’s crust is ancient. Yet even the shallower and more easily accessible water, part which has been replenished by rain over the past half century, still greatly exceeds all other unfrozen water on Earth.</p>
<p>Found throughout landscapes on all continents, groundwater plays a vital role in not only sustaining water-dependent ecosystems during period of low or absent rainfall, but also providing people with access to safe water, especially off-grid communities. In drylands that stretch across around 40% of the world, groundwater is often the only perennial source of freshwater. It is estimated that <a href="https://www.un-igrac.org/sites/default/files/resources/files/Groundwater_around_world.pdf">half of</a> the world’s drinking water and <a href="https://doi.org/10.5194/gmd-14-1037-2021">a quarter of</a> all the water used in irrigation are currently sourced by groundwater drawn from wells and springs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453325/original/file-20220321-23-mdis59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A woman uses a well" src="https://images.theconversation.com/files/453325/original/file-20220321-23-mdis59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453325/original/file-20220321-23-mdis59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453325/original/file-20220321-23-mdis59.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453325/original/file-20220321-23-mdis59.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453325/original/file-20220321-23-mdis59.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453325/original/file-20220321-23-mdis59.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453325/original/file-20220321-23-mdis59.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">‘Water, water every where nor any drop to drink’ – a woman pumps fresh deep.
groundwater in coastal Bangladesh while surrounded by brackish surface
water.</span>
<span class="attribution"><span class="source">Richard Taylor</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Groundwater flowing within rocks underground known as aquifers is generally more resilient to climate variability and change than surface waters. Therefore droughts – whose frequency and severity are amplified by global warming – often increase dependence upon groundwater. This was recently witnessed in Cape Town in South Africa, which narrowly avoided <a href="https://www.nature.com/articles/d41586-018-05649-1">“day zero”</a> when the municipal water supply would be turned off. It has even been argued that <a href="https://doi.org/10.1371/journal.pone.0107358">human evolution itself</a> relied on continuous spring discharges during periods of extreme drought.</p>
<p>The world is expected to become more dependent upon fresh water stored as groundwater as societies adapt to a world in which rain falls <a href="https://doi.org/10.1038/nclimate3110">less frequently but in heavier bursts</a> brought about by climate change. Recent evidence suggests such changes in rainfall may <a href="https://doi.org/10.1038/s41586-019-1441-7">favour groundwater replenishment</a> in the tropics to cope with drier periods, and that irrigation with groundwater could address climate change threats to rain-fed agriculture. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453330/original/file-20220321-13-831xiz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Man in field beside pipe" src="https://images.theconversation.com/files/453330/original/file-20220321-13-831xiz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453330/original/file-20220321-13-831xiz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453330/original/file-20220321-13-831xiz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453330/original/file-20220321-13-831xiz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453330/original/file-20220321-13-831xiz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=541&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453330/original/file-20220321-13-831xiz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=541&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453330/original/file-20220321-13-831xiz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=541&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Onion crops irrigated by groundwater in southeastern Niger.</span>
<span class="attribution"><span class="source">Boukari Issoufou</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Exploited and contaminated</h2>
<p>Despite groundwater’s invaluable attributes, it is not immune to overexploitation or contamination. For instance, continued groundwater pumping in some of the world’s most productive food-growing regions – California’s Central Valley, the North China Plain, northwest India, the High Plains of the US – is rapidly depleting reserves. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/453320/original/file-20220321-13-1ny1oc1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of global groundwater depletion" src="https://images.theconversation.com/files/453320/original/file-20220321-13-1ny1oc1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/453320/original/file-20220321-13-1ny1oc1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=242&fit=crop&dpr=1 600w, https://images.theconversation.com/files/453320/original/file-20220321-13-1ny1oc1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=242&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/453320/original/file-20220321-13-1ny1oc1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=242&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/453320/original/file-20220321-13-1ny1oc1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=304&fit=crop&dpr=1 754w, https://images.theconversation.com/files/453320/original/file-20220321-13-1ny1oc1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=304&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/453320/original/file-20220321-13-1ny1oc1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=304&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Groundwater is running low in some of the world’s main agricultural areas.</span>
<span class="attribution"><a class="source" href="https://www.unesco.org/reports/wwdr/2022/en">UNESCO</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Similarly, some of the world’s fastest growing cities such as <a href="https://doi.org/10.1007/s10040-007-0226-5">Dhaka (Bangladesh)</a> and <a href="https://doi.org/10.1007/s10040-020-02236-5">Nairobi (Kenya)</a> are struggling to reliably provide safe water as the groundwater below is running out. Groundwater depletion in both contexts disproportionately affects lower-income households and farmers who are typically less able to engage in a “race to the bottom” and drill deeper wells.</p>
<p>Groundwater in coastal areas is also becoming more salty, thanks to intensive pumping and rising sea levels, which both serve to drive sea water into underground aquifers. This salinisation especially affects groundwater in low-lying nations across the world and has the potential <a href="https://www.worldbank.org/en/news/press-release/2021/09/13/climate-change-could-force-216-million-people-to-migrate-within-their-own-countries-by-2050">to force</a> millions of people to leave their homes. </p>
<p>Use of groundwater is also impaired by the natural leaching of pollutants such as <a href="https://www.who.int/water_sanitation_health/water-quality/unicef-who-arsenic-primer.pdf">fluoride and arsenic</a> from their host rocks – arsenic leaking into wells in Bangladesh has been described as the <a href="https://www.who.int/bulletin/archives/78%289%291093.pdf">largest mass poisoning</a> in history. Human activity, be it indiscriminate use of pesticides and fertilisers in agriculture, inadequate sanitation infrastructure, or ineffective regulation of industrial practices, also threatens the sustainability of groundwater use.</p>
<h2>A common resource</h2>
<p>As groundwater is out of sight, it has long been out of mind. Many countries struggle to monitor and evaluate their supplies, and only invest a tiny fraction of the resources they allocate to tracking surface water. There has also been a lack of investment in training and education in groundwater science, known as hydrogeology. </p>
<p>Like fisheries, groundwater is a commons, which is constantly threatened by <a href="https://www.jstor.org/stable/1724745">The Tragedy of the Commons</a> – a situation where individual users act in their own self-interest to deplete or degrade a resource, contrary to the collective good. The Nobel-Prize winning economist Elinor Ostrom showed that <a href="https://doi.org/10.1017/CBO9781316423936">cooperation is possible</a>, however. She identified a set of conditions from case studies that included shared use of groundwater in which a community of users regulates individual access to develop common-pool resources prudently and sustainably. If we are to make groundwater visible, and ensure it provides equitable and climate-resilient access to water throughout the world, then such cooperative approaches are urgently required.</p>
<hr>
<figure class="align-right ">
<img alt="Imagine weekly climate newsletter" src="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/434988/original/file-20211201-21-13avx6y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<p><strong><em>Don’t have time to read about climate change as much as you’d like?</em></strong>
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<hr><img src="https://counter.theconversation.com/content/179620/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Taylor receives funding from UKRI, The Royal Society and FCDO. </span></em></p><p class="fine-print"><em><span>Mohammad Shamsudduha ('Shams') does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Our planet’s invaluable natural store of freshwater is woefully neglected.Richard Taylor, Professor of Hydrogeology, UCLMohammad Shamsudduha ('Shams'), Associate Professor in Humanitarian Science, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1778392022-02-27T08:33:18Z2022-02-27T08:33:18ZNigeria’s plastic pollution is harming the environment: steps to combat it are overdue<figure><img src="https://images.theconversation.com/files/448357/original/file-20220224-33175-1cixqce.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/man-puts-into-bags-plastic-waste-collected-from-various-news-photo/967173232?adppopup=true">Pius Utomi Ekpei/ AFP via Getty Images </a></span></figcaption></figure><p>A key theme at <a href="https://www.unep.org/news-and-stories/story/un-environment-assembly-tackle-plastics-green-recovery-and-chemicals">this year’s</a> United Nations Environment Assembly in Kenya is plastic pollution. It will be returning to a <a href="https://sdg.iisd.org/events/world-environment-day-2018/#:%7E:text=India%20will%20serve%20as%20the,%2C%20'Beat%20Plastic%20Pollution'">theme</a> from 2018 World Environment Day. The <a href="https://link.springer.com/article/10.1007/s11356-020-11736-6">evidence</a> for the prevalence and consequences of plastic pollution has been building up and the assembly needs to <a href="https://theconversation.com/plastic-pollution-is-a-global-problem-heres-how-to-design-an-effective-treaty-to-curb-it-176226">lead action</a> on this issue.</p>
<p>Individuals, communities, businesses, and governments all have a part to play to reduce plastic pollution in their environments.</p>
<p>The 2018 World Environment Day provided much-needed impetus for some countries to launch or appraise their plastic pollution initiatives. An example is <a href="https://www.unep.org/news-and-stories/press-release/india-sets-pace-global-race-beat-plastic-pollution">India</a>, which committed itself to proscribing and eliminating all single-use plastics in all Indian states by 2022. <a href="https://www.businessinsider.in/which-states-in-india-have-banned-plastic/articleshow/70218756.cms">Many Indian states</a> have keyed into this initiative and a national ban on most single-use plastics is due to <a href="https://www.hindustantimes.com/india-news/states-told-to-ready-single-use-plastic-ban-starting-july-1-101645382162965.html">take effect</a> from 1 July 2022.</p>
<p>Unfortunately, Nigeria hasn’t done much in this regard. Compared to other <a href="https://planetpatrol.co/blog/2021/06/01/which-countries-have-banned-plastic-bags/#:%7E:text=Kenya%20%E2%80%93%20the%20%E2%80%9Cworld's%20strictest%E2%80%9D,blocking%20waterways%20and%20drainage%20systems">developing countries</a> such as Kenya, Rwanda, <a href="https://allafrica.com/stories/202107300434.html">Uganda</a> and <a href="https://worldexpeditions.com/Blog/tanzania-plastic-ban-what-travellers-need-to-know">Tanzania</a>, its commitments to combating plastic pollution are far below average. </p>
<h2>Plastic pollution thrives in Nigeria</h2>
<p>Lagos, Nigeria’s megacity of <a href="https://worldpopulationreview.com/world-cities/lagos-population">nearly 16 million people</a>, produces between 13,000 and 15,000 tonnes of waste per day, including <a href="https://phys.org/news/2021-04-cleanup-plastic-polluted-lagos-beach.html">2,250 tonnes of plastic</a>, according to a local recycling business.</p>
<p>Nigerian lawmakers <a href="https://www.thecable.ng/reps-pass-bill-to-ban-plastic-bags-prescribe-3-year-jail-term-for-sale">considered</a> a bill in 2019 to prohibit the use of plastic bags. The bill is still in limbo. It is yet to undergo further reading and has not been enacted into law. Consequently, plastic bags are being indiscriminately used in Nigeria. </p>
<p>The evidence of the harm this does is mounting.</p>
<p>My research group published the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0075951119300970?via%20percent%203DDihub">first empirical finding</a> of freshwater microplastics in Nigeria. We used snails from the Osun River in southwest Nigeria as biological indicators of plastic pollution. Snails in the river had consumed polyethylene plastic bags, which were common along riverbanks. </p>
<p>We have also <a href="https://link.springer.com/article/10.1007/s11356-020-08763-8">found</a> plastic polymers such as polyester, polypropylene, acrylonitrile butadiene styrene, styrene-ethylene butylene styrene, and chlorinated polyethylene in the Osun and Ogun Rivers. The plastic polymers recorded in our study are traceable to different sources such as textiles, biscuit wrappers, automotive tyre cords, bottle caps, and drinking straws. We also saw larger items in the rivers, such as tyres, plastic bags and plastic bottles. Studies indicate that such plastics could affect the <a href="https://www.sciencedirect.com/science/article/abs/pii/S004896971931530X?via%3Dihub">life history</a>, survival, growth and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0269749117341234?via%3Dihub">development of insect larvae</a> into adults. </p>
<p>Our studies of plastic pollution in Nigeria, particularly freshwater and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0048969720325304?via%20percent%203Dihub#!">marine</a> environments, have recorded plastics in <a href="https://link.springer.com/article/10.1007/s11356-020-09031-5">fish</a> too.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-microplastics-found-in-nigerias-freshwaters-raise-a-red-flag-147432">Why microplastics found in Nigeria's freshwaters raise a red flag</a>
</strong>
</em>
</p>
<hr>
<h2>Effects of plastics</h2>
<p>When animals <a href="https://link.springer.com/chapter/10.1007/698_2016_21">ingest plastics</a>, it blocks the gut and windpipe and reduces their physiological fitness. Aquatic animals can also become entangled in plastics, <a href="https://pubmed.ncbi.nlm.nih.gov/23809333/">resulting</a> in malnutrition and death.</p>
<p>Plastics <a href="https://link.springer.com/article/10.1007/s11356-020-11736-6">degrade</a> the aesthetic value of Nigerian landscapes and aquatic systems. This compromises cultural ecosystem services such as ecotourism.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/lagos-beaches-have-a-microplastic-pollution-problem-128133">Lagos beaches have a microplastic pollution problem</a>
</strong>
</em>
</p>
<hr>
<p>Plastic pollution has become such a serious problem in Nigeria that it has virtually become a sign of human activity or visits to a location. People who visit beaches, riverbanks, parks and waterfalls frequently dump their plastic bottles carelessly, despite the dangers that such plastics pose to the environment. </p>
<p>In one <a href="https://theconversation.com/we-found-a-rare-insect-at-an-unspoilt-stream-in-nigeria-sign-of-a-need-to-explore-and-protect-171966">case</a>, plastic bottles were found at a natural site where an ecologically important rare insect was found.</p>
<p>Our <a href="https://link.springer.com/article/10.1007/s11356-020-11736-6">studies</a> show that plastic can affect the water-holding capacity of drains, river channels and reservoirs. This <a href="https://library.oapen.org/bitstream/id/3b91f626-4aed-4058-86ad-3a8334bf6b3a/1002">leads</a> to flooding of adjacent lands and loss of biological diversity and livelihoods. </p>
<p>Losing natural sites to plastic pollution also means people don’t get the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0272494413000224">health benefits</a> of outdoor activity.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/nigerian-river-snails-carry-more-microplastics-than-rhine-snails-126622">Nigerian river snails carry more microplastics than Rhine snails</a>
</strong>
</em>
</p>
<hr>
<h2>Action to end plastic pollution in Nigeria</h2>
<p>Combating plastic pollution in Nigeria will require action on several fronts.</p>
<p>The first step will be to address poor waste management practices prevalent in the country. </p>
<p>Also, businesses will have to stop providing free plastic bags. These bags are often <a href="https://link.springer.com/article/10.1007/s11356-020-11736-6">discarded</a> after a single use. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/kenya-should-be-focused-on-recycling-not-banning-plastic-bags-79679">Kenya should be focused on recycling, not banning plastic bags</a>
</strong>
</em>
</p>
<hr>
<p>To discourage the practice, governments should levy a high fee on each plastic bag that shoppers get at malls and markets. Paying for a bag could discourage people from discarding them after a single use. Paper bags, <a href="https://www.dw.com/en/the-ugandan-women-making-paper-bags-from-bananas/av-44642676">used in Uganda</a>, should be encouraged. Since packaging is the <a href="https://ourworldindata.org/plastic-pollution#total-plastic-waste-by-country">leading cause</a> of plastic pollution in the environment, the Nigerian government needs to launch a campaign and crack down on plastic bags and bottles in the country. The public will need to be educated on the three Rs: reduce, recycle, and reuse plastic materials. </p>
<p>Water sachets and bottles have proliferated in Nigeria due to a lack of drinkable water in many homes. The government needs to <a href="https://theconversation.com/top-tips-for-tackling-plastic-pollution-from-marine-scientists-164602">educate the public</a> about the dangers of discarding water sachets and bottles in the environment. And it must ensure access to clean water. </p>
<p>Whatever strategy the government employs will be ineffective unless the long-awaited “plastic pollution bill” is passed by Nigerian legislators and swiftly signed into law.</p>
<p>Citizens and leaders have the responsibility of bequeathing an environment that future Nigerians can be proud of. Kenya, Uganda, Tanzania, Rwanda, and other countries have taken steps to protect their environments from more plastic pollution. Nigeria can no longer afford to wait.</p><img src="https://counter.theconversation.com/content/177839/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Emmanuel O. Akindele works for Obafemi Awolowo University, Ile-Ife, Nigeria. He receives funding from the German Academic Exchange Service and the British Ecological Society. </span></em></p>The Nigerian government must do more to combat increasing plastic pollution in the country.Emmanuel O. Akindele, Senior Lecturer, Obafemi Awolowo UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1774532022-02-23T19:13:03Z2022-02-23T19:13:03ZClimate change is warping our fresh water cycle – and much faster than we thought<figure><img src="https://images.theconversation.com/files/447974/original/file-20220223-15-1xyzaw5.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4665%2C3456&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Shutterstock</span></span></figcaption></figure><p>Fresh water cycles from ocean to air to clouds to rivers and back to the oceans. This constant shuttling can give us the illusion of certainty. Fresh water will always come from the tap. Won’t it? </p>
<p>Unfortunately, that’s not guaranteed. Climate change is shifting where the water cycle deposits water on land, with drier areas becoming drier still, and wet areas becoming even wetter. </p>
<p>Our research <a href="https://www.nature.com/articles/s41586-021-04370-w">published today in <em>Nature</em></a> has found the water cycle is changing faster than we had thought, based on changes in our oceans. </p>
<p>This concerning finding underlines the ever more pressing need to end the emissions of gases warming the atmosphere before the water cycle changes beyond recognition.</p>
<p>If this sounds serious, it is. Our ability to harness fresh water makes possible modern society. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/447981/original/file-20220223-21-tecojb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Rain falling on ocean" src="https://images.theconversation.com/files/447981/original/file-20220223-21-tecojb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/447981/original/file-20220223-21-tecojb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/447981/original/file-20220223-21-tecojb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/447981/original/file-20220223-21-tecojb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/447981/original/file-20220223-21-tecojb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/447981/original/file-20220223-21-tecojb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/447981/original/file-20220223-21-tecojb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">It’s hard to track how much rain falls on our oceans.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<h2>The water cycle has already changed</h2>
<p>As the Earth warms up, the water cycle has begun to intensify in a “<a href="https://www.doi.org/10.1111/nyas.14337">wet-gets-wetter-dry-gets-drier</a>” pattern. </p>
<p>This means more and more freshwater is leaving dry regions of the planet and ending up in wet regions.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-water-cycle-is-intensifying-as-the-climate-warms-ipcc-report-warns-that-means-more-intense-storms-and-flooding-165590">The water cycle is intensifying as the climate warms, IPCC report warns – that means more intense storms and flooding</a>
</strong>
</em>
</p>
<hr>
<p>What might this look like? <a href="https://theconversation.com/the-water-cycle-is-intensifying-as-the-climate-warms-ipcc-report-warns-that-means-more-intense-storms-and-flooding-165590">Weather, intensified</a>. In relatively dry areas, more intense droughts, more often. In relative wet areas, more extreme storms and flooding. </p>
<p>Think of the <a href="https://www.theguardian.com/environment/2022/feb/15/us-west-megadrought-worst-1200-years-study">megadrought afflicting </a>America’s west, of the unprecedented floods <a href="https://www.theguardian.com/environment/2021/jul/16/climate-scientists-shocked-by-scale-of-floods-in-germany">in Germany</a>, or of the increase in severe rainfall seen in <a href="https://www.theatlantic.com/science/archive/2022/02/mumbai-flooding-climate-change/621471/">cities like Mumbai</a>. </p>
<p>This shift is already happening. In its landmark 2021 report, the UN’s Intergovernmental Panel on Climate Change (IPCC) drew on this growing body of research to conclude climate change was already causing <a href="https://www.ipcc.ch/report/sixth-assessment-report-working-group-i/">long-term changes to the water cycle</a>. </p>
<p>The changes we’re seeing are just the start. Over the next few decades, this water cycle intensification could make it much harder for people to get reliable supplies of fresh water across large areas of the planet. </p>
<p>Troublingly, while we know the water cycle is intensifying, we don’t fully know how much and how fast. That’s where the ocean comes into play. </p>
<h2>How to use the ocean as a rain gauge</h2>
<p>The main reason it’s hard to directly measure changes to the water cycle is that we don’t have enough measurements of rainfall and evaporation over our planet. </p>
<p>On a practical level, it’s very hard to set up permanent rain gauges or evaporation pans on the 70% of our planet’s surface covered in water. Plus, when we assess change over the long term, we need measurements from decades ago. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/447980/original/file-20220223-15-1l9rs2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="evaporation off ocean" src="https://images.theconversation.com/files/447980/original/file-20220223-15-1l9rs2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/447980/original/file-20220223-15-1l9rs2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/447980/original/file-20220223-15-1l9rs2p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/447980/original/file-20220223-15-1l9rs2p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/447980/original/file-20220223-15-1l9rs2p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/447980/original/file-20220223-15-1l9rs2p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/447980/original/file-20220223-15-1l9rs2p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Evaporation over the Barents Sea, which has been warming rapidly.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>The solution scientists have landed on is to use the ocean. Many may not realise the ocean can be less or more salty depending on the region. For instance, the Atlantic is saltier than the Pacific on average. </p>
<p>Why? Rain. When fresh water falls as rain on the ocean, it dilutes the sea water and makes it less salty. When water evaporates from the surface, the salt is left behind, increasing the salinity. This means we can use the better-recorded changes in the ocean’s salinity as a kind of rain gauge to detect water cycle changes. </p>
<p>Earlier research used this method to track changes to the salinity at the ocean’s surface. This research suggested the water cycle is <a href="https://www.doi.org/10.1126/science.1212222">intensifying dramatically</a>. </p>
<p>Unfortunately, the ocean does not stay still like a conventional rain gauge. Currents, waves and circular eddy currents keep the ocean’s waters in constant motion. This uncertainty has left a question mark over how exact the link between salinity and water cycle change actually is. </p>
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Read more:
<a href="https://theconversation.com/predicting-droughts-and-floods-why-were-studying-19th-century-ocean-records-164985">Predicting droughts and floods: why we're studying 19th-century ocean records</a>
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<p>In response, we have developed new methods enabling us to precisely link changes in the ocean’s salinity to changes in the part of the water cycle moving fresh water from warmer to colder regions. Our estimates indicate how the broader water cycle is changing in the atmosphere, over land and through our oceans. </p>
<p>What did we find in our <a href="https://www.nature.com/articles/s41586-021-04370-w">new study</a>? The fresh water equivalent of 123,000 times the waters of Sydney Harbour have shifted from the tropics to the cooler areas since 1970. That’s an estimated 46,000 to 77,000 cubic kilometres of water. </p>
<p>This is consistent with an intensification of the water cycle of up to 7%. That means up to 7% more rain in wetter areas and 7% less rain (or more evaporation) in dryer areas. </p>
<p>This is at the upper end of estimates established by several <a href="https://doi.org/10.1038/srep38752">previous studies</a>, which suggested an intensification closer to 2-4%. </p>
<p>Unfortunately, these findings suggest potentially disastrous changes to the water cycle may be approaching faster than previously thought. </p>
<h2>What would the future be like with an altered water cycle?</h2>
<p>If our water cycle is getting more intense at a faster rate, that means stronger and more frequent extreme droughts and rainfall events. </p>
<p>Even if the world’s governments meet their target and keep global warming to a ceiling of 2°C, the IPCC predicts we would still endure extreme events <a href="https://www.ipcc.ch/report/sixth-assessment-report-working-group-i/">an average of 14% stronger</a> relative to a baseline period of 1850-1900. </p>
<p>Some people and ecosystems will be hit harder than others, as the IPCC report last year made clear. For example, Mediterranean nations, south-west and south-east Australia, and central America will all become drier, while monsoon regions and the poles will become wetter (or snowier).</p>
<p>In dry areas hit by these water cycle changes, we can expect to see real threats to the viability of cities unless alternatives such as desalination are put in place.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/447982/original/file-20220223-19-t000s8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Hand under tap with no water coming out" src="https://images.theconversation.com/files/447982/original/file-20220223-19-t000s8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/447982/original/file-20220223-19-t000s8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/447982/original/file-20220223-19-t000s8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/447982/original/file-20220223-19-t000s8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/447982/original/file-20220223-19-t000s8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/447982/original/file-20220223-19-t000s8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/447982/original/file-20220223-19-t000s8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Droughts are likely to be more severe and more common in dry parts of the world.</span>
<span class="attribution"><span class="source">Shutterstock</span></span>
</figcaption>
</figure>
<p>What should we do? You already know the answer. </p>
<p>Decades of scientific research have shown the extremely clear relationship between greenhouse gas emissions and rising global temperatures, which in turn drives water cycle intensification. </p>
<p>This is yet another reason why we must move as quickly as humanly possible towards net-zero emissions to reduce the damage from climate change. </p>
<p>The changes to the water cycle we observed were largely due to older emissions, from the mid 20th century and earlier. We have increased our emissions dramatically since then. </p>
<p>What comes next is entirely up to us.</p><img src="https://counter.theconversation.com/content/177453/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Taimoor Sohail receives funding from the Australian Research Council. </span></em></p><p class="fine-print"><em><span>Jan Zika receives funding from the Australian Research Council and has received funding from the Natural Environment Research Council (United Kingdom).</span></em></p>Dry regions will get drier and wet regions wetter as the climate changes. How quickly? Quicker than we thought, unfortunately.Taimoor Sohail, Postdoctoral research associate, UNSW SydneyJan Zika, Associate Professor, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.