tag:theconversation.com,2011:/ca/topics/dead-zones-18643/articlesDead zones – The Conversation2023-09-14T15:02:42Ztag:theconversation.com,2011:article/2132972023-09-14T15:02:42Z2023-09-14T15:02:42ZAs climate change warms rivers, they are running out of breath – and so could the plants and animals they harbor<figure><img src="https://images.theconversation.com/files/547729/original/file-20230912-15-x93l4l.jpg?ixlib=rb-1.1.0&rect=22%2C7%2C5069%2C3382&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Potomac River spills over Great Falls west of Washington, D.C..</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/great-falls-of-the-potomac-river-virginia-maryland-at-great-news-photo/1449185440">Marli Miller/UCG/Universal Images Group via Getty Images</a></span></figcaption></figure><p>As climate change warms rivers, they are losing dissolved oxygen from their water. This process, which is called <a href="https://www.iucn.org/resources/issues-brief/ocean-deoxygenation">deoxygenation</a>, was already known to be occurring in large bodies of water, like oceans and lakes. A study that colleagues and I just published in <a href="https://www.nature.com/articles/s41558-023-01793-3">Nature Climate Change</a> shows that it is happening in rivers as well. </p>
<p>We documented this change using a type of artificial intelligence called a deep learning model – specifically, a <a href="https://www.geeksforgeeks.org/deep-learning-introduction-to-long-short-term-memory/">long short-term memory model</a> – to predict water temperature and oxygen levels. The data that we fed the model included past records of water temperature and oxygen concentrations in rivers, along with past weather data and the features of adjoining land – for example, whether it held cities, farms or forests. </p>
<p>The original water temperatures and oxygen data, however, were measured sparsely and often in different periods and with different frequency. This made it challenging before our study to compare across rivers and in different periods.</p>
<p>Using all of this information from 580 rivers in the U.S. and 216 rivers in central Europe, our AI program reconstructed day-to-day temperatures and oxygen levels in those rivers from 1981 to 2019. We also used future climate projections to predict future water temperature and oxygen levels. This enabled us to consistently compare past and future river water temperatures and oxygen levels across hundreds of rivers, which would not have been possible without using AI. </p>
<p>On average, we found, rivers were warming by 0.29 degrees Fahrenheit (0.16 degrees Celsius) per decade in the U.S. and 0.49 F (0.27 C) per decade in central Europe. Deoxygenation rates reached as high as 1% to 1.5% loss per decade. These rates are faster than deoxygenation rates occurring in oceans, and slower than those in lakes and coastal regions. </p>
<p>Urban rivers are warming up most rapidly, while rivers in agricultural areas are losing oxygen most rapidly. This could be partly due to <a href="https://theconversation.com/to-reduce-harmful-algal-blooms-and-dead-zones-the-us-needs-a-national-strategy-for-regulating-farm-pollution-186286">nutrient pollution</a>, which combines with warmer waters to fuel large blooms of algae. When the algae die and decompose, this process depletes dissolved oxygen in the water.</p>
<h2>Why it matters</h2>
<p>Oxygen is crucial for plants, animals, fish and aquatic insects that live in rivers. These organisms <a href="https://www.usgs.gov/special-topics/water-science-school/science/dissolved-oxygen-and-water">breathe dissolved oxygen from river water</a>. If oxygen levels drop too low, river species will suffocate. </p>
<p>While scientists know that oceans and lakes have been losing oxygen in a warming climate, we have mainly thought that rivers were safe from this problem. Rivers are shallow, and fast-moving water can absorb oxygen directly from the air <a href="https://www.usgs.gov/special-topics/water-science-school/science/dissolved-oxygen-and-water">more rapidly</a> than standing water. Rivers also harbor plants that make oxygen.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/c5JZKUssy9c?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Chelsea Miller of the Maryland Department of Natural Resources explains why dissolved oxygen is important in aquatic environments and shows how researchers test for it.</span></figcaption>
</figure>
<p>The health of rivers affects everything in and around them, from aquatic life to humans who rely on the rivers for water, food, transportation and recreation. Warming rivers with low oxygen could suffer fish die-offs and degraded water quality. Fisheries, tourism and even property values along rivers could decline, affecting livelihoods and economies.</p>
<p>As the air warms in a changing climate, rivers will also become warmer. As a liquid’s temperature increases, <a href="https://doi.org/10.1038/s44221-023-00038-z">its capacity to hold gases declines</a>. This means that climate change will further reduce dissolved oxygen in river water. </p>
<p>At extreme levels, this process can create <a href="https://oceanservice.noaa.gov/facts/deadzone.html">dead zones</a> where fish and other species cannot survive. Dead zones already form in coastal areas, such as the <a href="https://www.noaa.gov/news-release/noaa-and-partners-announce-below-average-dead-zone-measured-in-gulf-of-mexico">Gulf of Mexico</a> and <a href="https://ohioseagrant.osu.edu/research/issues/habs">Lake Erie</a>. We found that some rivers, especially in warmer areas like Florida, may face more low-oxygen days in the future. </p>
<p>Low oxygen in rivers also can promote chemical and biological reactions that lead to the <a href="https://pubs.usgs.gov/circ/circ1133/heavy-metals.html">release of toxic metals from river sediments</a> and increased emissions of greenhouse gases, such as <a href="https://doi.org/10.1038/s41558-019-0665-8">nitrous oxide</a> and <a href="https://doi.org/10.1038/s41586-023-06344-6">methane</a>. </p>
<h2>What’s next</h2>
<p>Most of our data on dissolved oxygen was collected during the day, when plants in rivers are actively making oxygen through photosynthesis, powered by sunlight. This means that our findings may underestimate the low-oxygen problem. At night, when plants aren’t producing oxygen, dissolved oxygen levels could be lower.</p>
<p>I see this research as a wake-up call for more study of how climate change is <a href="https://doi.org/10.1029/2021EF002603">affecting river water quality worldwide</a>. Better monitoring and more analysis can make the full scope of river deoxygenation clearer. Ultimately, I hope more research will lead to policy changes that promote responsible land use and water management and better stewardship of rivers, our planet’s veins.</p>
<p><em>The <a href="https://theconversation.com/us/topics/research-brief-83231">Research Brief</a> is a short take about interesting academic work.</em></p><img src="https://counter.theconversation.com/content/213297/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Li Li has received funding from the US National Science Foundation and the US Department of Energy. She 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 her academic appointment.
</span></em></p>When water warms, it holds less oxygen, and this can harm aquatic life and degrade water quality. A new study finds that climate change is driving oxygen loss in hundreds of US and European rivers.Li Li (李黎), Professor of Civil and Environmental Engineering, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1862862022-07-18T12:26:45Z2022-07-18T12:26:45ZTo reduce harmful algal blooms and dead zones, the US needs a national strategy for regulating farm pollution<figure><img src="https://images.theconversation.com/files/474164/original/file-20220714-32338-xz3rmp.jpeg?ixlib=rb-1.1.0&rect=52%2C0%2C8713%2C5835&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Satellite photo of an algal bloom in western Lake Erie, July 28, 2015.</span> <span class="attribution"><a class="source" href="https://eoimages.gsfc.nasa.gov/images/imagerecords/86000/86327/erie_oli_2015209_lrg.jpg">NASA Earth Observatory</a></span></figcaption></figure><p>Midsummer is the time for forecasts of the size of this year’s “dead zones” and algal blooms in major lakes and bays. Will the <a href="https://www.nola.com/news/environment/article_bfc1ba32-e2ac-11ec-9909-5fd0e4edb56b.html">Gulf of Mexico dead zone</a> be the size of New Jersey, or only as big as Connecticut? Will Lake Erie’s bloom blossom to a <a href="https://www.toledoblade.com/local/2014/08/03/Water-crisis-grips-area/stories/20140803090">human health crisis</a>, or just devastate the <a href="https://www.ectinc.com/projects/economic-benefits-costs-of-reducing-harmful-algal-blooms-in-lake-erie/">coastal economy</a>? </p>
<p>We are scientists who each have spent almost 50 years figuring out <a href="https://scholar.google.com/citations?user=ARkaE6cAAAAJ&hl=en">what causes dead zones</a> and what it will take to resuscitate them and reduce <a href="https://scholar.google.com/citations?user=-K4wV5QAAAAJ&hl=en">risks of toxic blooms of algae</a>. Researchers can <a href="https://theconversation.com/forecasting-dead-zones-and-toxic-algae-in-us-waterways-a-bad-year-for-lake-erie-43747">forecast</a> these phenomena quite well and have calculated the nitrogen and phosphorus pollution cuts needed to reduce them. </p>
<p>These targets are now written into formal government commitments to clean up <a href="https://doi.org/10.1016/j.jglr.2016.09.007">Lake Erie</a>, the <a href="https://doi.org/10.1073/pnas.1705293114">Gulf</a> and the <a href="https://doi.org/10.1002/eap.2384">Chesapeake Bay</a>. Farmers and land owners nationwide received US$30 billion to support conservation, including practices designed to reduce water pollution, from <a href="https://www.ewg.org/news-insights/news-release/new-ewg-database-details-30-billion-spent-us-farm-conservation-programs">2005 to 2015</a>, and are scheduled to receive $60 billion more between <a href="https://crsreports.congress.gov/product/pdf/IF/IF12024#:%7E:text=Spending%20for%20agricultural%20conservation%20programs,are%20reauthorized%20with%20no%20changes.">2019 and 2028</a>. </p>
<p>But these efforts have fallen short, mainly because controls on nutrient pollution from agriculture are <a href="https://doi.org/10.3389/fmars.2019.00123">weak and ineffective</a>. In our view, there is no shortage of solutions to this problem. What’s needed is technological innovation and stronger political will. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map showing a zone with low oxygen values along the Louisiana coast." src="https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=299&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=299&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=299&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=376&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=376&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474157/original/file-20220714-32176-2cyi2q.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=376&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Gulf of Mexico hypoxic (dead) zone in 2021, which measured 6,334 square miles (16,400 square kilometers). Lower values represent less dissolved oxygen in the water.</span>
<span class="attribution"><a class="source" href="https://nrtwq.usgs.gov/nwqn/Sites/GULF_PRELIM/cruise2021-Final_2021_map_KM.jpg">Louisiana Universities Marine Consortium</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Problems return to Lake Erie</h2>
<p>State and federal agencies have known since the 1970s that overloading lakes and bays with nutrients generates huge blooms of algae. When the algae die and decompose, they deplete oxygen in the water, creating dead zones that can’t support aquatic life. But in each of these “big three” water bodies, efforts to curb nutrient pollution have been slow and halting. </p>
<p>The U.S., Canada and cities around Lake Erie started working to reduce phosphorus pollution in the lake from domestic and industrial wastes <a href="https://clevelandhistorical.org/items/show/58?tour=12&index=11">in 1972</a>. Water quality quickly improved, dead zones shrank and harmful algal blooms became less frequent. </p>
<p>But the scourges of <a href="https://doi.org/10.1016/j.jglr.2014.02.004">low-oxygen waters and sometimes-toxic algae</a> reappeared in the mid-1990s. This time, the source was mostly runoff from farm soils saturated with phosphorus from repeated applications of fertilizer and manure. Climate change made matters worse: Warmer waters hold less oxygen and <a href="https://blog.nature.org/science/2014/08/27/understanding-the-lake-erie-algal-bloom-toledo-water-shutdown/">cause faster growth of algae</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bar chart showing phosphorus entering Lake Erie 1967-2001." src="https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=324&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=324&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=324&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=407&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=407&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474182/original/file-20220714-33068-wgdrw3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=407&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Phosphorus loads to Lake Erie, 1967-2001. Nonpoint sources are wide areas without a distinct discharge point, such as farm fields.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1016/j.jglr.2014.02.004">Scavia et al., 2014</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Slow progress in the Chesapeake Bay</h2>
<p>Nitrogen and phosphorus reach the Chesapeake Bay from sources including wastewater treatment plants; air pollution emitters, such as factories and cars; and runoff from urban, suburban and agricultural lands. In 1987 the federal government and states around the bay agreed to reduce these flows by <a href="https://www.epa.gov/chesapeake-bay-tmdl/chesapeake-bay-agreements">40% by the year 2000</a> to restore water quality. But this effort relied on voluntary action and failed to make much progress. </p>
<p>In 2010 the states and the U.S. Environmental Protection Agency entered <a href="https://www.epa.gov/chesapeake-bay-tmdl/chesapeake-bay-tmdl-document">a legally binding commitment</a>, to reduce pollutant loads below prescribed maximum levels needed to restore water quality. If the states make inadequate progress, the EPA can limit or rescind their permitting authority, and the states may lose federal funding. </p>
<p>Nitrogen and phosphorus pollution has been <a href="https://www.chesapeakeprogress.com/clean-water/2017-watershed-implementation-plans">reduced</a> primarily by tightening permit requirements and upgrading wastewater treatment plants. Air pollution controls for power plants and vehicles have also reduced nitrogen reaching the bay. Water quality has improved, and the yearly dead zone has <a href="https://doi.org/10.1016/j.scitotenv.2021.152722">shrunk modestly</a>. </p>
<p>But with the commitment’s 2025 deadline nearing, nitrogen loads have been reduced by less then 50% of the targeted amounts, phosphorus by <a href="https://www.chesapeakebay.net/news/pressrelease/bay_program_model_shows_decline_in_nutrient_sediment_pollution_entering_the">less then 64%</a>. Most of the remaining pollution comes from <a href="https://doi.org/10.1002/jeq2.20101">farm runoff and urban stormwater</a>.
Intensifying agriculture in rural areas and sprawl in urban areas are counteracting other cleanup efforts. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/Og4gYUR_m94?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Cleaning up water bodies with large watersheds, like the Chesapeake Bay (64,000 square miles/165,000 square kilometers, involves many states and thousands of pollution sources.</span></figcaption>
</figure>
<h2>Failure in the Gulf of Mexico</h2>
<p>The Gulf of Mexico dead zone forms every year during the summer, fueled by nutrients washing down the Mississippi River from Midwest farms. It <a href="https://www.noaa.gov/news-release/larger-than-average-gulf-of-mexico-dead-zone-measured">typically covers at least 6,000 square miles</a>, sometimes expanding up to 9,000 square miles (23,000 square kilometers), and affects an area very rich in fisheries. </p>
<p>In 2001, the EPA and 12 Mississippi River basin states agreed to take action to reduce the Gulf dead zone by two-thirds by 2015. Researchers estimated that this would require <a href="https://www.epa.gov/sites/default/files/2015-03/documents/2008_1_31_msbasin_sab_report_2007.pdf">reducing nitrogen loads reaching the Gulf by about 45%</a>, mostly from the Corn Belt. </p>
<p>Now that deadline has been <a href="https://www.epa.gov/sites/default/files/2015-10/documents/htf_report_to_congress_final_-_10.1.15.pdf">extended to 2035</a>. Nitrogen and phosphorus loadings at the mouth of the Mississippi River <a href="https://nrtwq.usgs.gov/nwqn/#/GULF">haven’t budged in 30 years</a>, so actions taken to date have <a href="https://www.epa.gov/ms-htf/history-hypoxia-task-force">failed to shrink the Gulf dead zone</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Bar chart showing measurements of the Gulf of Mexico dead zone since 1985." src="https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/474158/original/file-20220714-32145-o1yeg7.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">Since 2017 the Gulf of Mexico dead zone has covered an average of 5,380 square miles (14,000 square kilometers), which is 2.8 times larger than the 2035 target set by a federal task force.</span>
<span class="attribution"><a class="source" href="https://www.noaa.gov/news-release/larger-than-average-gulf-of-mexico-dead-zone-measured">LUMCON/NOAA</a></span>
</figcaption>
</figure>
<h2>Overwhelmed by agriculture</h2>
<p>In 2020, the EPA and Ohio <a href="https://epa.ohio.gov/static/Portals/35/tmdl/MaumeeNutrient/Maumee-Nutrient-TMDL-062022.pdf">adopted an agreement</a> similar to that for the Chesapeake to reduce phosphorus pollution below a prescribed maximum load from the Maumee River watershed at the western end of Lake Erie, where algal blooms occur most often. To date, Mississippi River basin states and even the EPA have <a href="https://doi.org/10.15779/Z38T727G2Q">opposed similarly mandating maximum pollution loads</a> to reduce the Gulf of Mexico dead zone. </p>
<p>Despite substantial government subsidies to implement various agricultural management practices, nitrogen and phosphorus pollution in streams in <a href="https://doi.org/10.1371/journal.pone.0195930">Iowa</a> and <a href="https://www2.illinois.gov/epa/topics/water-quality/watershed-management/excess-nutrients/Documents/NLRS-2021-Biennial-Report-FINAL.pdf">Illinois</a> has actually increased over the 1980-1996 baseline of the Gulf agreement. </p>
<p>Even with increasing crop yields and more efficient use of fertilizer, the expansion and intensification of agriculture in the Midwest has overwhelmed any water quality gains. One driver is ethanol production, which has increased <a href="https://www.eia.gov/todayinenergy/detail.php?id=36892">fortyfold</a> since the Gulf action plan was adopted in 2001. Today, over 40% of corn grown in the U.S. is <a href="https://www.ers.usda.gov/topics/crops/corn-and-other-feedgrains/feedgrains-sector-at-a-glance/">used for ethanol</a>, mostly in the Midwest, while most of the rest is used to feed animals. </p>
<p>In all three regions, the growth of large-scale livestock farms – <a href="https://www.vox.com/the-highlight/22344953/iowa-select-jeff-hansen-pork-farming">hogs in the Midwest</a>, <a href="https://www.delmarvanow.com/story/news/2021/10/29/84-poultry-operations-raised-water-pollution-concerns-yet-few-fined-report-environmental-watchdog/6180639001/">poultry around the Chesapeake Bay</a> – is also contributing to nutrient pollution. <a href="https://doi.org/10.1016/j.resconrec.2020.105065">Improper management of animal waste</a> adds to nitrogen and phosphorus loads in soils and local waters. </p>
<p>Studies show that agriculture contributes <a href="http://scavia.seas.umich.edu/wp-content/uploads/2018/02/Final-Report-Update-20160415.pdf">85% of Lake Erie’s Maumee River phosphorus load</a>, <a href="https://pubs.usgs.gov/circ/1486/cir1486.pdf">65% of the Chesapeake Bay’s nitrogen load</a> and 73.2% of the nitrogen load and 56% of the phosphorus load to the <a href="https://doi.org/10.1111/1752-1688.12905">Gulf of Mexico</a>. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1223304943265648642"}"></div></p>
<h2>Incentives aren’t working</h2>
<p>We believe the evidence is clear that the largely voluntary approaches taken to date, with technical assistance and substantial public financing, are not working. </p>
<p>Economists have called for a <a href="https://doi.org/10.1111/1752-1688.13010">fundamental shift in policies controlling agricultural pollution</a>. Instead of offering polluters subsidies to clean up their operations, these experts argue, the strategy should be to pay farmers for performance, based on environmental outcomes that can be measured <a href="https://doi.org/10.13031/trans.12379">or predicted</a> at appropriate scales and specific places. </p>
<p>Under this approach, government would set limits on the amount of nutrients that can be lost to the environment, and farmers would choose how to meet them, based on what kinds of action work best for their specific soils and climate. For example, <a href="https://doi.org/10.1038/s41586-020-03042-5">restoring wetlands</a> within the watershed could help to capture nutrients that unavoidably wash off of farmlands. </p>
<p>The ongoing shift to electric vehicles offers an opportunity to grow far less grain for ethanol, which <a href="https://theconversation.com/the-us-biofuel-mandate-helps-farmers-but-does-little-for-energy-security-and-harms-the-environment-168459">doesn’t even help the climate</a>. And in the long run, developing <a href="https://www.scientificamerican.com/article/heres-how-much-food-contributes-to-climate-change/">efficient, plant-based food systems</a> would both reduce nutrient pollution and limit climate change. </p>
<p>In June 2022, the Government Accountability Office concluded that federal agencies charged with preventing and controlling harmful algal blooms and dead zones under a <a href="https://www.govinfo.gov/content/pkg/PLAW-105publ383/pdf/PLAW-105publ383.pdf">1998 law</a> have <a href="https://www.gao.gov/assets/gao-22-104449.pdf">failed to establish a national program</a> to address these issues. Fifty years after the federal Clean Water Act was enacted, we believe such a program is long overdue.</p><img src="https://counter.theconversation.com/content/186286/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Donald Boesch does not work for, consult, own shares in, or receive funding from any company or organization that would benefit from this article. He currently receives no external funding, but previously received funding from the National Science Foundation, Environmental Protection Agency, National Oceanic and Atmospheric Administration, and the Walton Family Foundation.</span></em></p><p class="fine-print"><em><span>Donald Scavia does not work for, consult, own shares in, or receive funding from any company or organization that would benefit from this article. He has received research funding from the National Science Foundation, Environmental Protection Agency, National Oceanic and Atmospheric Administration, and the Erb Family Foundation.</span></em></p>Nutrient pollution fouls lakes and bays with algae, killing fish and threatening public health. Progress curbing it has been slow, mainly because of farm pollution.Donald Boesch, Professor of Marine Science, University of Maryland Center for Environmental ScienceDonald Scavia, Professor Emeritus of Environment and Sustainability, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1628122021-07-05T15:34:29Z2021-07-05T15:34:29ZNitrous oxide, a powerful greenhouse gas, is on the rise from ocean dead zones<figure><img src="https://images.theconversation.com/files/408973/original/file-20210629-25-zdi7m8.jpg?ixlib=rb-1.1.0&rect=69%2C116%2C5112%2C3068&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Seabed sediments in Bermuda mangroves consumed nitrous oxide from the seawater. Restoring coastal ecosystems might help curb climate change.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>In October 2019, I set sail with a team of scientists aboard the Canadian Coast Guard Vessel John P. Tully in the northeast Pacific Ocean, off the coast of Vancouver Island. Battling rough seas and lack of sleep, we spent the better part of a week working shoulder-to-shoulder in a small stand-up refrigerator, analyzing seafloor sediments to learn more about the effects of low-oxygen conditions on deep-sea environments. </p>
<p>When organisms die, they sink through the water column, consuming oxygen in the sub-surface ocean as they decompose. This leads to bands of oxygen-depleted water called oxygen minimum zones, or “dead zones.” </p>
<p>These harsh environments are uninhabitable for most organisms. Although they occur naturally in some areas, dead zones often appear after fertilizer and sewage wash downstream into coastal areas, sparking algal blooms, which then die off and decompose. </p>
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<p>One <a href="https://doi.org/10.1002/lol2.10174">of our studies from that expedition</a> suggested that the sediments below oxygen-depleted waters are a significant source of nitrous oxide (N2O). This gas is released into the atmosphere when deep water rises to the surface in a process known as upwelling. </p>
<p>Nitrous oxide, more commonly known as “laughing gas,” is a potent greenhouse gas, 300 times more powerful than carbon dioxide. Global <a href="https://doi.org/10.5194/essd-10-985-2018">emissions of N2O are increasing</a> as a result of human activities that stimulate its production.</p>
<h2>N2O hotspots</h2>
<p>The oceans currently account for <a href="https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter06_FINAL.pdf">around 25 per cent</a> of global N2O emissions, and scientists are working to improve estimates of marine contributions. Most research has focused on oxygen minimum zones, which are known as <a href="https://doi.org/10.1038/ngeo2469">hotspots of N2O emissions</a>. </p>
<figure class="align-left ">
<img alt="Experiment room on a ship full of gear." src="https://images.theconversation.com/files/407532/original/file-20210621-21-13m4dt1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/407532/original/file-20210621-21-13m4dt1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/407532/original/file-20210621-21-13m4dt1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/407532/original/file-20210621-21-13m4dt1.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/407532/original/file-20210621-21-13m4dt1.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/407532/original/file-20210621-21-13m4dt1.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/407532/original/file-20210621-21-13m4dt1.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">Sediment incubation experiments underway in cold room on board the Tully.</span>
<span class="attribution"><span class="source">(Brett Jameson)</span></span>
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<p>Warming of the ocean due to climate change is driving the <a href="https://oceana.ca/en/blog/climate-change-driving-ocean-oxygen-declines">expansion of marine oxygen minimum zones</a> globally. This has led to speculation that <a href="https://doi.org/10.3389/fmars.2019.00157">N2O emissions from the oceans will continue to increase</a> and further accelerate climate change. Our results indicate that even more N2O production may be expected where these low-oxygen waters are in contact with the seafloor. </p>
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<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=401&fit=crop&dpr=1 600w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=401&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=401&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=504&fit=crop&dpr=1 754w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=504&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/369797/original/file-20201117-13-180ibt9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=504&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><strong><em>This story is part of <a href="https://theconversation.com/uk/topics/oceans-21-96784">Oceans 21</a></em></strong>
<br><em>Our series on the global ocean opened with <a href="https://oceans21.netlify.app/">five in-depth profiles</a>. Look out for new articles on the state of our oceans in the lead up to the UN’s next climate conference, COP26. The series is brought to you by The Conversation’s international network.</em></p>
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<p>Nitrogen is an essential component to life on Earth and exists in the environment in many different forms. Specialized groups of single-celled microbes use nitrogen-containing compounds, such as ammonium and nitrate, for energy to drive cellular functions. These metabolic reactions mediate the transformation of nitrogen between its various states in the environment, during which N2O can leak out into the environment as a byproduct.</p>
<p>Aside from its effects as a greenhouse gas, N2O is also the predominant <a href="https://www.doi.org/10.1126/science.1176985">ozone-depleting</a> substance emitted to the atmosphere.</p>
<h2>Mangroves as N2O banks</h2>
<p>Our team travelled to Bermuda in the fall of 2020 to measure N2O emissions in a pristine mangrove forest in collaboration with the Bermuda Institute of Ocean Sciences. These sediments were shallower and accessible to snorkelers, which allowed us to thoroughly investigate their role in N2O cycling under different environmental conditions.</p>
<p>We found the seabed sediments in the Bermuda mangroves were actually consuming N2O from the overlying seawater. Similar N2O “sinks” have been described previously in other pristine systems, <a href="https://doi.org/10.3389/fmars.2016.00040">including estuaries</a>, <a href="https://doi.org/10.1038/srep25701">mangroves</a> and even <a href="https://doi.org/10.1080/1943815X.2010.497492">terrestrial soils</a>. </p>
<figure class="align-center ">
<img alt="a man swimming near shore towing a small row boat" src="https://images.theconversation.com/files/407534/original/file-20210621-34897-vz0ybj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/407534/original/file-20210621-34897-vz0ybj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=392&fit=crop&dpr=1 600w, https://images.theconversation.com/files/407534/original/file-20210621-34897-vz0ybj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=392&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/407534/original/file-20210621-34897-vz0ybj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=392&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/407534/original/file-20210621-34897-vz0ybj.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=492&fit=crop&dpr=1 754w, https://images.theconversation.com/files/407534/original/file-20210621-34897-vz0ybj.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=492&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/407534/original/file-20210621-34897-vz0ybj.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=492&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">UVic PhD candidate Brett Jameson returns with samples collected from Bermudian mangroves.</span>
<span class="attribution"><span class="source">(Brett Jameson)</span></span>
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<p>The ability of these areas to draw N2O from the atmosphere is tied to the concentrations of nitrogen-containing nutrients in the environment. Nitrous oxide production is inhibited when these nitrogen-containing nutrients are in short supply. When nutrient levels are sufficiently low, marine habitats can act as net consumers of N2O.</p>
<p>Sediments that act as N2O sinks can also act as <a href="https://doi.org/10.1111/gcb.12923">net sources of N2O</a> to the atmosphere when subjected to increased nitrogen loading from agricultural runoff and urban waste water. Indeed, mangroves and other near-shore ecosystems that experience sustained inputs of dissolved nitrogen tend to be large N2O emitters.</p>
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Read more:
<a href="https://theconversation.com/new-mangrove-forest-mapping-tool-puts-conservation-in-reach-of-coastal-communities-151458">New mangrove forest mapping tool puts conservation in reach of coastal communities</a>
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<p>The extent to which pristine environments can serve as buffers against increases in atmospheric N2O concentrations is still uncertain. Most studies to date have focused on densely populated and highly disturbed regions of Europe and Asia, which act as sources of N2O. This leaves much to be learned about the role of pristine marine habitats as N2O sinks and their overall influence on global N2O budgets. </p>
<h2>Targeting fertilizer</h2>
<p>Although reducing future marine N2O emissions hinges on the more complex problem of slowing the growth and spread of marine oxygen minimum zones, actions to conserve and restore pristine coastal environments are tractable interventions that can be implemented in the short term.</p>
<p>At present, human agricultural practices account for over <a href="https://theconversation.com/new-research-nitrous-oxide-emissions-300-times-more-powerful-than-co-are-jeopardising-earths-future-147208">two-thirds</a> of global N2O emissions. As a result, much attention has been directed at reducing the amount of <a href="https://fertilizercanada.ca/wp-content/uploads/2018/08/NERP-Science-Review-Paper-.pdf">excess nitrogen added to agricultural soils via fertilizer</a>. Since nutrients that are not taken up by plants often end up in watersheds that drain into the ocean, policies that address overuse of fertilizers will also benefit adjacent aquatic ecosystems.</p>
<p>However, further reducing marine emissions will require a multifaceted approach that also addresses coastal development and waste-water disposal practices in heavily impacted areas. </p>
<p>The United Nations has declared 2021 as the start of a <a href="https://oceandecade.org/">Decade of Ocean Science for Sustainable Development</a>. Detailing the vital link between oceans and climate change has never been more timely than now.</p><img src="https://counter.theconversation.com/content/162812/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Brett Jameson receives funding from the University of Victoria, the Canadian Healthy Oceans Network (CHONe), the National Sciences and Engineering Research Council (NSERC), and the Bermuda Institute of Ocean Sciences. </span></em></p>Nitrous oxide is a potent greenhouse gas, 300 times more powerful than carbon dioxide. Global emissions of N2O are on the rise as a result of human activities — and their impact on ocean ecosystems.Brett Jameson, PhD Candidate in Biological Oceanography , University of VictoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1460692021-03-09T13:32:33Z2021-03-09T13:32:33ZGrowing food and protecting nature don’t have to conflict – here’s how they can work together<figure><img src="https://images.theconversation.com/files/387851/original/file-20210304-17-izkl00.jpg?ixlib=rb-1.1.0&rect=25%2C8%2C2770%2C1986&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Paul and Becky Rogers converted 14 acres of land in Kent County, Mich. to habitat that supports pollinators, songbirds and wildlife.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/tbUyzx">USDA/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Growing food in a sustainable, environmentally friendly way – while also producing enough of it – is among the most important challenges facing the U.S. and the world today. </p>
<p>The ongoing COVID-19 pandemic has reminded us that food security can’t be taken for granted. Putting affordable food on the table requires both innovative producers and well-functioning markets and global supply chains. With <a href="https://theconversation.com/why-farmers-are-dumping-milk-down-the-drain-and-letting-produce-rot-in-fields-136567">disruptions to the system</a>, prices rise, food is scarce – and people go hungry. </p>
<p>But feeding the world’s <a href="https://www.worldometers.info/world-population/us-population/">7.8 billion</a> people sustainably – <a href="https://doi.org/10.1038/s41586-018-0594-0">including 332 million Americans</a> – presents significant environmental challenges. Farming uses <a href="https://www.routledge.com/Water-for-Food-Water-for-Life-A-Comprehensive-Assessment-of-Water-Management/Molden/p/book/9781844073962">70% of the world’s fresh water</a>. Fertilizers pollute water with nitrates and phosphates, sparking algal blooms and creating dead zones like the one that forms every summer in the <a href="https://doi.org/10.1002/lob.10351">Gulf of Mexico</a>. </p>
<p>Clear-cutting land for farms and ranches is the main driver of <a href="https://www.journals.uchicago.edu/doi/abs/10.1093/reep/rew013">deforestation</a>. Overall, the planet loses about 48,000 square miles (125,000 square kilometers) of forest each year. Without habitat, wildlife disappears. Farming also produces roughly <a href="https://www.ipcc.ch/site/assets/uploads/2018/02/ipcc_wg3_ar5_chapter11.pdf">one-quarter of global greenhouse gas emissions</a>. </p>
<p>All of these challenges make balancing food production with environmental security a crucial issue for the Biden administration, which is working to address both a <a href="https://www.cnbc.com/2021/01/22/bidens-executive-orders-address-hunger-crisis-raise-minimum-wage.html">hunger crisis</a> and an <a href="https://www.bbc.com/news/world-us-canada-55829189">environmental crisis</a> in the U.S.</p>
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<figcaption><span class="caption">Climate change is wreaking havoc on weather patterns, making conditions more challenging for farmers. But scholars and the Biden administration believe agriculture can be part of the solution.</span></figcaption>
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<h2>Two different pathways</h2>
<p>As an <a href="https://scholar.google.com/citations?user=DulicT8AAAAJ&hl=en">economist studying food systems</a>, I’m keenly aware that trying to provide affordable food and a thriving agricultural sector while also preserving the environment can result in <a href="http://link.springer.com/book/10.1007%2F978-3-319-22662-0">many trade-offs</a>. Consider the different strategies that the U.S. and Northern Europe have pursued: The U.S. prioritizes increased agricultural output, while the EU emphasizes environmental services from farming. </p>
<p>Over the past 70 years, the U.S. has <a href="https://www.ers.usda.gov/data-products/international-agricultural-productivity/">increased crop production</a> with ever more <a href="https://www.ers.usda.gov/webdocs/publications/89114/err-249.pdf?v=0">sophisticated seed technologies</a> and highly mechanized farming methods that employ far fewer workers. These new technologies have contributed to farm productivity growth which has, in turn, allowed U.S. farm output to rise without significant growth in the aggregate economic index of agricultural input use.</p>
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<p>This approach contrasts sharply with Northern Europe’s strategy, which emphasizes using less land and other inputs in order to protect the environment. Nonetheless, by achieving a comparable rate of agricultural productivity growth (output growth minus the growth rate inputs), Northern Europe has been able to <a href="https://www.ers.usda.gov/webdocs/publications/89114/err-249.pdf?v=0">maintain its level of total farm output</a> over the past three decades. </p>
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<h2>Boosting prices versus benefiting nature</h2>
<p>The U.S. also has a long history of <a href="https://farmdocdaily.illinois.edu/2020/06/production-controls-set-aside-acres-part-1-reviewing-history.html">setting aside agricultural land</a> that dates back nearly a century. In response to low prices in the 1920s, farmers had flooded the market with grain, pork and other products, desperately seeking to boost revenues but only pushing prices down further. </p>
<p>Under the Agricultural Adjustment Act of 1933, the U.S. government paid farmers to reduce their output and limited the supply of land under cultivation to boost farm prices. This strategy is <a href="https://farmdocdaily.illinois.edu/2020/06/production-controls-set-aside-acres-part-1-reviewing-history.html">still in use today</a>. </p>
<p>In 1985 the U.S. launched a new program that created real incentives to protect environmentally sensitive land. Farmers who enroll in the <a href="https://www.fsa.usda.gov/Assets/USDA-FSA-Public/usdafiles/Conservation/PDF/35_YEARS_CRP_B.pdf">Conservation Reserve Program</a> “rent” environmentally valuable tracts to the U.S. Department of Agriculture for 10-15 years. Withdrawing these acres from production provides food and shelter for pollinators and wildlife, reduces erosion and improves water quality.</p>
<p>But this is a voluntary program, so enrollment ebbs and flows in tandem with crop prices. For example, when corn, soy and wheat prices fell in the late 1980s and early 1990s, enrollment grew. Then with the commodity price boom of 2007, farmers could make more money from cultivating the land. Protected acreage dropped more than 40% through 2019, erasing many of the environmental benefits that had been achieved. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/385667/original/file-20210222-17-1hvmgcd.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/385667/original/file-20210222-17-1hvmgcd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/385667/original/file-20210222-17-1hvmgcd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=459&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385667/original/file-20210222-17-1hvmgcd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=459&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385667/original/file-20210222-17-1hvmgcd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=459&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385667/original/file-20210222-17-1hvmgcd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=577&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385667/original/file-20210222-17-1hvmgcd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=577&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385667/original/file-20210222-17-1hvmgcd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=577&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">Enrollment in the USDA Conservation Reserve Program dropped by almost 13 million acres from 2007 to 2016.</span>
<span class="attribution"><a class="source" href="https://www.fsa.usda.gov/Assets/USDA-FSA-Public/usdafiles/Conservation/PDF/ChangeInCRPAcreagefrom2007_2016.pdf">U.S. Department of Agriculture</a></span>
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<p>Rental rates for agricultural land in the U.S. vary widely, with the most productive lands bringing the highest rent. Current rental rates under the Conservation Reserve Program 2021 range from US$243 per acre in Cuming, Nebraska to <a href="https://www.fsa.usda.gov/programs-and-services/conservation-programs/reports-and-statistics/conservation-reserve-program-statistics/index">just $6 in Sutton, Texas</a>.</p>
<p>The EU also began <a href="https://eur-lex.europa.eu/legal-content/en/ALL/?uri=CELEX%3A31988R1272">setting aside farmland</a> to <a href="https://eur-lex.europa.eu/legal-content/en/ALL/?uri=CELEX%3A31988R1272">curb overproduction</a> in 1988. Now, however, their program focuses heavily on environmental quality. Policy reforms in 2013 required farmers to allocate 5% of their land to <a href="https://doi.org/10.1111/1477-9552.12217">protected ecological focus areas</a>. The goal is to generate long-term environmental benefits by prioritizing nature. </p>
<p>This program supports both production and conservation. Within this mix of natural and cultivated lands, wild pollinators benefit both native plants and crops. Birds, insects and small predators offer natural bio-control of pests. In this way, “rewilded” tracts foster biodiversity while also <a href="https://doi.org/10.1016/j.tree.2020.06.012">improving crop yields</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/387068/original/file-20210301-20-140maye.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/387068/original/file-20210301-20-140maye.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/387068/original/file-20210301-20-140maye.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=198&fit=crop&dpr=1 600w, https://images.theconversation.com/files/387068/original/file-20210301-20-140maye.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=198&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/387068/original/file-20210301-20-140maye.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=198&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/387068/original/file-20210301-20-140maye.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=249&fit=crop&dpr=1 754w, https://images.theconversation.com/files/387068/original/file-20210301-20-140maye.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=249&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/387068/original/file-20210301-20-140maye.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=249&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A rewilded area in Germany, near Dresden.</span>
<span class="attribution"><span class="source">Thomas Hertel</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Who will feed the world?</h2>
<p>What would happen if the U.S., a major exporter of agricultural products, followed the EU model and permanently withdrew land from production to improve environmental quality? Would such action make food unaffordable for the world’s poorest consumers? </p>
<p>In a study that I conducted in 2020 with colleagues at Purdue and the U.S. Department of Agriculture, we set up a computer model to find out. We wanted to chart what might happen to food prices across the globe through 2050 if the U.S. and other rich economies followed Northern European conservation strategies. Our analysis focused on <a href="http://www.fao.org/publications/sofi/2020/en/">the world’s most food-insecure region</a>, sub-Saharan Africa. </p>
<p>We discovered that altering food production in this way would raise food prices in that region by about 6%. However, this upward price trend could be reversed by <a href="https://doi.org/10.1016/j.euroecorev.2020.103479">investing in local agriculture and new technologies</a> to increase productivity in Africa. In short, our research suggested that conserving the environment in the U.S. doesn’t have to cause food insecurity in other countries. </p>
<h2>Implications for US farm policy</h2>
<p>Many experts on hunger and agriculture agree that to feed a growing global population, world food output must <a href="https://doi.org/10.1371/journal.pone.0066428">increase substantially</a> in the next several decades. At the same time, it’s clear that agriculture’s <a href="https://doi.org/10.1038/nature10452">environmental impacts need to shrink</a> in order to protect the natural environment. </p>
<p>In my view, meeting these twin goals will require renewed government investments in research and dissemination of new technologies. Reversing a two-decade <a href="https://www.thelugarcenter.org/newsroom-news-409.html">decline in science funding</a> will be key. Agriculture is now a <a href="https://doi.org/10.1093/aepp/ppx045">knowledge-driven industry</a>, fueled by <a href="http://link.springer.com/chapter/10.1007/978-1-4419-0658-8_8">new technologies and improved management practices</a>. Publicly funded research laid the foundations for these advances. </p>
<p>To reap environmental gains, I believe the U.S. Department of Agriculture will need to revamp and stabilize the Conservation Reserve Program, so that it is economically viable and enrollment does not fluctuate with market conditions. The Trump administration <a href="https://www.usda.gov/media/press-releases/2021/02/05/usda-extends-general-signup-conservation-reserve-program">reduced incentives and rental payment rates</a>, which drove down enrollments. The Biden administration has already taken a modest step forward by <a href="https://www.usda.gov/media/press-releases/2021/02/05/usda-extends-general-signup-conservation-reserve-program">extending the yearly sign-up for the program indefinitely</a>.</p>
<p>[<em>Over 100,000 readers rely on The Conversation’s newsletter to understand the world.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=100Ksignup">Sign up today</a>.]</p>
<p>As I see it, following Northern Europe’s model by permanently protecting ecologically rich areas, while simultaneously investing in knowledge-driven agricultural productivity, will enable the U.S. to better preserve wildlife and its natural environment for future generations, while maintaining an affordable food supply.</p><img src="https://counter.theconversation.com/content/146069/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Thomas Hertel receives funding from the National Science Foundation, the US Department of Agriculture and the US Department of Energy.</span></em></p>It’s possible to feed the world’s 7.8 billion people with more environmentally friendly farming practices. Here’s how.Thomas Hertel, Professor of Agricultural Economics, Purdue UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1469802020-11-02T13:24:50Z2020-11-02T13:24:50ZA few heavy storms cause a big chunk of nitrogen pollution from Midwest farms<figure><img src="https://images.theconversation.com/files/364813/original/file-20201021-23-1sop9qc.jpg?ixlib=rb-1.1.0&rect=26%2C0%2C3000%2C1998&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Corn plants in a flooded field near Emden, Ill., May 29, 2019.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.ie/detail/news-photo/corn-grows-in-a-saturated-farm-field-on-may-29-2019-near-news-photo/1152539969?adppopup=true">Scott Olson/Getty Images</a></span></figcaption></figure><p>Some effects of extreme weather are visible – like <a href="https://www.marketwatch.com/story/devastating-august-derecho-prompts-usda-to-cut-iowa-corn-acres-by-550-000-11599849936">half a million acres of flattened corn in Iowa</a> left behind after a <a href="https://theconversation.com/what-is-a-derecho-an-atmospheric-scientist-explains-these-rare-but-dangerous-storm-systems-140319">derecho</a> that hit the Midwestern United States on Aug. 10. </p>
<p>Other effects are harder to measure, but can be just as harmful. One example is agricultural nitrogen runoff from farmlands in the Mississippi River Basin. It mainly comes from fertilizer that farmers apply to <a href="https://pubs.usgs.gov/fs/old.2003/fs-105-03/">millions of acres of crops</a>. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/366499/original/file-20201029-19-1c171bd.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Map of Mississippi River basin" src="https://images.theconversation.com/files/366499/original/file-20201029-19-1c171bd.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/366499/original/file-20201029-19-1c171bd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=550&fit=crop&dpr=1 600w, https://images.theconversation.com/files/366499/original/file-20201029-19-1c171bd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=550&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/366499/original/file-20201029-19-1c171bd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=550&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/366499/original/file-20201029-19-1c171bd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=691&fit=crop&dpr=1 754w, https://images.theconversation.com/files/366499/original/file-20201029-19-1c171bd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=691&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/366499/original/file-20201029-19-1c171bd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=691&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Mississippi River Basin covers over 1.245 million square miles across 32 U.S. states and two Canadian provinces.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Mississippi_River_System#/media/File:Mississippiriver-new-01.png">Shannon1/Wikipedia</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Plants can’t use all of the nitrogen in fertilizer because fertilizers are usually applied in excess. This excess can wash off farm fields into local rivers and lakes, degrading water quality and <a href="https://theconversation.com/how-your-diet-contributes-to-nutrient-pollution-and-dead-zones-in-lakes-and-bays-118902">stimulating algae blooms</a>. Traveling down the Mississippi River, it contributes to the yearly formation of a <a href="https://coastalscience.noaa.gov/news/large-dead-zone-measured-in-gulf-of-mexico/">dead zone in the northern Gulf of Mexico</a>, covering several thousand square miles; oxygen levels there are so low that fish and shellfish cannot survive. </p>
<p>Excess nitrogen in drinking water also <a href="https://www.wsj.com/articles/farms-more-productive-than-ever-are-poisoning-drinking-water-in-rural-america-11547826031">threatens public health</a>. Ingesting high levels of nitrate, a nitrogen compound, can <a href="https://www.atsdr.cdc.gov/toxfaqs/tf.asp?id=1186&tid=258">reduce red blood cells’ ability to transport oxygen</a>, a condition that is especially dangerous for infants. </p>
<p>My work as a <a href="https://scholar.google.com/citations?user=VI_Lb-YAAAAJ&hl=en">quantitative ecologist</a> examines how ecosystems respond to external factors such as adding nitrogen. In a recently published study, I worked with colleagues to quantify nitrogen runoff from land into rivers and streams. We found that infrequent but heavy rainfall events account for <a href="https://doi.org/10.1038/s43247-020-00020-7">one-third of annual total runoff and nitrogen leaching from soils</a> across the Mississippi Basin. This tells us that managing nitrogen is likely to be more challenging if climate change continues to make heavy rains more frequent.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/OQFjmWGONCA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">To use nitrogen fertilizer efficiently, farmers need to consider factors including yield goals, soil quality, chemistry and weather.</span></figcaption>
</figure>
<h2>Too much of a good thing</h2>
<p>Plants can’t grow without nitrogen, but using too much or applying it improperly can cause problems. In the U.S. Midwest, one of the <a href="https://pubs.usgs.gov/fs/fs155-99/fs155-99.html">most intensively farmed areas in the world</a>, farmers have added <a href="https://doi.org/10.5194/essd-10-969-2018">large amounts of synthetic nitrogen fertilizer</a> to the land to boost crop yields. </p>
<p>Long-term monitoring data from river gauges shows large year-to-year variations in the quantity of nitrogen that flows down from the Mississippi River Basin into the Gulf of Mexico. Yearly changes in farmers’ fertilizer use are not large enough to explain these fluctuations.</p>
<p>Studies show that annual total precipitation is a <a href="https://carnegiescience.edu/news/projected-precipitation-increases-are-bad-news-water-quality">significant factor in these changes</a>. But we know less about the role of daily rainfall – particularly heavy rains – in mobilizing and transporting nitrogen. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/366164/original/file-20201028-19-1obdcnf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Graph showing nitrogen runoff from Midwest states to the Gulf of Mexico, 1980-2017." src="https://images.theconversation.com/files/366164/original/file-20201028-19-1obdcnf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/366164/original/file-20201028-19-1obdcnf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=381&fit=crop&dpr=1 600w, https://images.theconversation.com/files/366164/original/file-20201028-19-1obdcnf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=381&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/366164/original/file-20201028-19-1obdcnf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=381&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/366164/original/file-20201028-19-1obdcnf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=479&fit=crop&dpr=1 754w, https://images.theconversation.com/files/366164/original/file-20201028-19-1obdcnf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=479&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/366164/original/file-20201028-19-1obdcnf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=479&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Stream gauge measurements show that the amount of dissolved inorganic nitrogen (DIN) moving from Mississippi River Basin states to the Gulf of Mexico fluctuates dramatically from year to year. Heavy rainfalls can produce higher nitrogen levels.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.1038/s43247-020-00020-7">Modified from Lu et al., 2020</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Heavy rains have an outsized impact</h2>
<p>My collaborators and I wanted to assess the impacts of extreme rainfall events in the Midwest. In this region, many cropped fields are laced with buried networks of drainage channels, known locally as <a href="https://en.wikipedia.org/wiki/Tile_drainage">tile drainage</a>. These pipelines are designed to move excess moisture out of fields. But they can also channel large surges of water and nutrients into rivers and streams after heavy rainfalls.</p>
<p>It is challenging to determine how individual rainfall events affect nitrogen leaching and movement within a <a href="https://www.britannica.com/science/drainage-basin">drainage basin</a>. Rain happens here and there, so it’s hard to distinguish a single storm’s impact from river gauge monitoring data. Rainfall events also vary a lot by season and intensity. </p>
<p>Our study used a well-tested model to quantify how much nitrogen is washed out by each rainfall event, as well as total nitrogen delivered to the Gulf of Mexico. We looked closely at heavy rainfall events, which we defined as the top 10% of historical daily precipitation amounts for any location in a given month. </p>
<p>Climate records show that over the past 20 years, a growing share of annual precipitation has come in heavy rainfall events across two-thirds of the Mississippi River Basin’s land area. The region that receives a total of more than 15.7 inches (400 millimeters) of heavy rain per year has expanded from areas in Louisiana and Arkansas northward to Corn Belt states like Illinois and Indiana, where nitrogen fertilizer is heavily used.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/366496/original/file-20201029-21-1uua7k7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="U.S. map showing more precipitation falling during very heavy events" src="https://images.theconversation.com/files/366496/original/file-20201029-21-1uua7k7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/366496/original/file-20201029-21-1uua7k7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=541&fit=crop&dpr=1 600w, https://images.theconversation.com/files/366496/original/file-20201029-21-1uua7k7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=541&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/366496/original/file-20201029-21-1uua7k7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=541&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/366496/original/file-20201029-21-1uua7k7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=679&fit=crop&dpr=1 754w, https://images.theconversation.com/files/366496/original/file-20201029-21-1uua7k7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=679&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/366496/original/file-20201029-21-1uua7k7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=679&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Percentage increases in the amount of precipitation falling in very heavy events (defined as the heaviest 1% of all daily events) from 1958 to 2012.</span>
<span class="attribution"><a class="source" href="https://nca2014.globalchange.gov/report/our-changing-climate/heavy-downpours-increasing#:~:text=National%20Climate%20Assessment%20Home&text=Heavy%20downpours%20are%20increasing%20nationally,Explore%20extreme%20precipitation.">Globalchange.gov</a></span>
</figcaption>
</figure>
<p>We found that one-third of annual total runoff and nitrogen leaching loss come from heavy rainfall events, which happen on only about nine days per year on average across the basin. Nearly half to three-quarters of heavy rainfall in the basin occurs in spring and summer, with a monthly peak in May. </p>
<p>This timing coincides with the planting and seed germinating stages of corn, when the plants are using <a href="http://nmsp.cals.cornell.edu/publications/factsheets/factsheet98.pdf">minimal amounts of nitrogen</a>. We wondered whether changing when and how farmers apply fertilizer could reduce nitrogen runoff.</p>
<h2>When to fertilize</h2>
<p>When during the year to apply fertilizer is a long-standing question in both <a href="https://theconversation.com/farmers-of-the-future-will-utilize-drones-robots-and-gps-37739">precision agriculture</a> and environmental science. Midwest farmers apply over 90% of nitrogen fertilizer before crops germinate in springtime and after harvesting. This means that a fair amount of available nitrogen accumulates in the soil before crops start taking it up. When heavy rainfalls occur, it is likely to be washed out. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1318214328403767303"}"></div></p>
<p>We set up modeling experiments to test whether postponing fertilizer application could make the water running off of farmlands cleaner. In our alternative fertilizer management scenario, we assumed fertilizer was applied only twice, after crops developed. We expected this would reduce the amount of unused nitrogen accumulating in soils.</p>
<p>Our results predicted that this modification could reduce nitrogen loading to the Gulf of Mexico by up to 16%. This would be a significant step toward goals set by the U.S. Environmental Protection Agency, which is working with states to reduce nutrient loads entering the Gulf of Mexico by <a href="https://archive.epa.gov/epa/newsreleases/states-develop-new-strategies-reduce-nutrient-levels-mississippi-river-gulf-mexico.html">20% by 2025 and 45% by 2035</a>. </p>
<p>However, even under the postponed fertilizer application scenario, we still found the frequent heavy rains in the recent decade could enhance nitrogen loss during summer and early fall. Scientists predict that if climate change continues at its current rate, it will cause <a href="https://nca2014.globalchange.gov/highlights/regions/midwest#intro-section-2">more extreme rainfall events in the Midwest</a>, which, we think, would reduce environmental benefits from alternative nitrogen management practices. </p>
<p>Reducing the amount of nitrogen that escapes from land into water bodies while maintaining food production is a significant challenge. Our study complements the well-known <a href="https://www.nrcs.usda.gov/wps/portal/nrcs/ia/technical/ecoscience/nutrient/nrcs142p2_008196/">4R concept</a> for managing nutrients: Using the right fertilizer product, at the right rate, at the right time, and in the right place. To get that timing right, our research shows that along with crop nitrogen demand, farmers should also consider the occurrence of heavy rainfall.</p>
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<p class="fine-print"><em><span>Chaoqun Lu receives funding from the National Science Foundation, Iowa State University, and the Iowa Nutrient Research Center.</span></em></p>New research shows that one-third of yearly nitrogen runoff from Midwest farms to the Gulf of Mexico occurs during a few heavy rainstorms. New fertilizing schedules could reduce nitrogen pollution.Chaoqun Lu, Assistant Professor of Ecology, Evolution and Organismal Biology, Iowa State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1364742020-06-01T15:55:12Z2020-06-01T15:55:12ZHow we’re turning local environmental problems into global issues by engineering nature<figure><img src="https://images.theconversation.com/files/338424/original/file-20200528-51496-1k4q5on.jpg?ixlib=rb-1.1.0&rect=277%2C179%2C3289%2C2817&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Tourists observe the shore chock full of sargassum in Bahia La Media Luna, near Akumal in Quintana Roo, Mexico, in August 2018.</span> <span class="attribution"><span class="source">(AP Photo/Eduardo Verdugo)</span></span></figcaption></figure><p>The current coronavirus pandemic is a poignant example of our hyperconnected planet. A small, localized infection in Wuhan, China, rapidly spread around the world on transcontinental flight paths in a remarkable and transformative fashion. </p>
<p>The consequences of a massively connected globe are real and, unfortunately, not limited to disease pandemics. </p>
<p>As an ecologist who studies landscape connectivity in natural environments and those altered by humans, I think about how <a href="https://doi.org/10.1101/2020.04.20.050302">human activities establish new connections across the Earth and reinforce others — and their consequences</a>. </p>
<p>One of the foremost human impacts on the planet comes from land modification, where large-scale conventional agriculture replaces high-diversity ecosystems with low-diversity crops. </p>
<p>At first glance, one might imagine that this fragmentation of natural habitat reduces connectivity. But a closer look reveals that the modifications act to move nutrients from fertilizers across farmers’ fields and into rivers, lakes and oceans with dramatic outcomes. </p>
<h2>Flowing water, flowing fertilizer</h2>
<p>Conventional farm fields often use a system of below-ground pipes to drain wetlands and to avoid soggy landscapes. The combination of these drain tiles, lost wetlands and absence of trees and other plants (called riparian buffers) mean that unused fertilizer and sediment move rapidly into streams and rivers. </p>
<p>These stream and rivers are often channelized (straightened and sometimes recast in concrete or metal) to move water rapidly across a region. But they also wind up rapidly shuttling excess nutrients to large water bodies, like a lake or an ocean, where they come to rest en masse. </p>
<p>In this distant ecosystem, the fertilizer does as it is designed to do: drive the exponential growth of plants, but in this case it’s feeding algae in the coastal ecosystem. In nature, this <a href="https://doi.org/10.1038/35012234">runaway growth is a hallmark of ecological instability</a>. </p>
<p>Because the algae are inedible to animals, they accumulate and form large green mats in the surface waters. The algae then die and sink slowly into the depths of the water, where in the dark, bacteria proliferate on the dead algae. These huge densities of bacteria make the deep waters devoid of oxygen, forming “dead zones,” and kill much of the local aquatic life. </p>
<h2>Connected aquatic ecosystems</h2>
<p><a href="https://www.doi.org/10.1126/science.1156401">Dead zones are increasing in number and size globally on the planet</a>, producing a pandemic of diseased ecosystems. Notably, this excessive algal growth is also further fuelled by climate warming.</p>
<p>Once again, nature’s profound connectedness may not stop here. Other even larger impacts can occur, as coastal zones may be connected to ocean currents that gather and move the fertilized algae across the globe. Tourist hot spots in the Caribbean and the Gulf of Mexico have mysteriously found <a href="http://www.doi.org/10.1126/science.aaw7912">sargassum, a macroalgae, gathered in gigantic and costly piles on beaches for almost a decade</a>. </p>
<p>Using impressive satellite pictures, scientists have shown that the seaweed-laden beaches are likely driven by actions far away in the Amazon coined the Great Atlantic Sargassum Belt. The story is familiar. </p>
<p>Agricultural run-off from the fields in the Amazon River watershed enter the ocean and, in a warming climate, fuel the exponential growth of sargassum seaweed. This time, the large algae get picked up by an oceanic current system that moves it thousands of kilometres to the Caribbean, Florida and Africa. </p>
<p>Other instances of macroalgal beach deposits, now collectively called <a href="https://doi.org/10.1038/nature12860">green and golden tides for the colour of the algae, appear to be populating the globe with increasing frequency</a>.</p>
<h2>Gluttonous snow geese</h2>
<p>Other distant impacts driven by nutrients and nature’s connectivity are also occurring. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/338422/original/file-20200528-51516-wf3d8x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/338422/original/file-20200528-51516-wf3d8x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/338422/original/file-20200528-51516-wf3d8x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/338422/original/file-20200528-51516-wf3d8x.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/338422/original/file-20200528-51516-wf3d8x.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/338422/original/file-20200528-51516-wf3d8x.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/338422/original/file-20200528-51516-wf3d8x.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">Migrating snow geese arrive at Middle Creek Wildlife Area in Lancaster County, Penn., in March 2015.</span>
<span class="attribution"><span class="source">(AP Photo/PennLive.com, Sean Simmers)</span></span>
</figcaption>
</figure>
<p>Snow geese populations, for example, that overwinter in the southern U.S. and eat cereal crops have <a href="http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.505.7684&rep=rep1&type=pdf">grown enormously since the 1950s</a>. Scientists documented the rise in snow geese parallel to the <a href="http://www.fwf.ag.utk.edu/mgray/wfs560/SnowGeese.pdf">increased application of industrial nitrogen as a fertilizer</a>.</p>
<p>The geese then migrate every summer to the Hudson Bay lowlands thousands of kilometres away. There, the dense flocks of crop-subsidized geese overgraze whole marsh ecosystems, leaving nothing but muddy flats behind. </p>
<p>While news of the globe’s hyperconnectivity is grim, it also holds in it a simple and hopeful solution. The flip side of nature’s connectivity is that “acting local” is indeed “thinking globally.” </p>
<p>Importantly, farmers recognize these problems. <a href="https://alus.ca/">Farming groups like ALUS in Canada</a> take the state of the environment seriously and play a leading role in agricultural land-use approaches that tackle these serious problems. </p>
<p>In a time where the ill effects of an over-connected planet are abundantly clear, we also need to slow the transmission of nutrients that <a href="https://open.spotify.com/show/6S5upA9eYVoPXxJoPchhOD">expand the planet’s diseased ecosystems</a>.</p><img src="https://counter.theconversation.com/content/136474/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin McCann receives funding from NSERC</span></em></p>The consequences of a massively connected globe are real — and not limited to disease pandemics.Kevin McCann, Full Professor, Biology, University of GuelphLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1189022019-07-11T14:08:55Z2019-07-11T14:08:55ZHow your diet contributes to nutrient pollution and dead zones in lakes and bays<figure><img src="https://images.theconversation.com/files/281826/original/file-20190628-94696-13spbr0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Charter boat Capt. Dave Spangler holds a sample of algae from Maumee Bay in Lake Erie, Sept. 15, 2017.</span> <span class="attribution"><a class="source" href="http://www.apimages.com/metadata/Index/Lake-Erie-Algae/70ba55b23a5a4f189c20b383141cf323/2/0">AP Photo/Paul Sancya, File</a></span></figcaption></figure><p>Every year in early summer, scientists at universities, research institutions and federal agencies release forecasts for the formation of “dead zones” and harmful algal blooms in the Gulf of Mexico, the Chesapeake Bay and Lake Erie. This year <a href="http://scavia.seas.umich.edu/hypoxia-forecasts/">the outlook is not good</a>. </p>
<p>The dead zone that forms annually in the Gulf of Mexico is likely to approach, if not surpass, record size at roughly 7,250 square miles. Another dead zone in the Chesapeake Bay is projected to be within the top 20% recorded over the past 20 years – about 2.1 cubic miles, equivalent to over 3.5 million Olympic-size swimming pools. And Lake Erie is also projected to set records, with almost 50,000 tons of potentially toxic algae. </p>
<p>The key factor driving these forecasts is winter and spring rainfall considerably above normal across the central U.S. The winter of 2018-2019 was the <a href="https://www.noaa.gov/news/us-records-wettest-winter-capped-by-cooler-wetter-february-2019">wettest on record</a> across the nation, and May was the <a href="https://www.ncei.noaa.gov/news/national-climate-201905">second-wettest month on record</a>. </p>
<p>Predicting the results isn’t rocket science. More rain means more flooding and more runoff from farmlands. These waters carry heavy loads of nutrients, mainly from fertilizer, that fuel algal blooms. The end results include <a href="https://www.thegazette.com/subject/news/government-treading-water-dead-zone-hypoxia-agricultural-runoff-fish-kill-nonpoint-source-pollution-surface-runoff-iowa-farmers-dnr-cover-crops-improve-water-quality-12022018">fish kills, closed beaches, possible drinking water alerts and loss of coastal property value</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/5LwbeK-QXNs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Water in the Gulf of Mexico dead zone can contain less than half of the oxygen levels needed to support fish.</span></figcaption>
</figure>
<h2>Treading water</h2>
<p>Algal blooms occur when water bodies become overloaded with nitrogen and phosphorus from farms, water treatment plants and other sources. Warm water and nutrients promote rapid growth of algae. Some strains can be toxic or even fatal to aquatic life and humans.</p>
<p>Eventually algae settle to the bottom and decay. This process depletes dissolved oxygen in the water, creating “dead zones” where oxygen levels are low enough to kill fish.</p>
<p>Scientists and public officials have understood this problem for decades, but progress toward addressing it has been painfully slow. Nutrient loads, dead zones and harmful algal blooms in these systems dominated by agriculture have <a href="https://theconversation.com/forecasting-dead-zones-and-toxic-algae-in-us-waterways-a-bad-year-for-lake-erie-43747">increased or held grudgingly steady for decades</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/281852/original/file-20190628-94712-x1bv35.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/281852/original/file-20190628-94712-x1bv35.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/281852/original/file-20190628-94712-x1bv35.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=515&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281852/original/file-20190628-94712-x1bv35.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=515&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281852/original/file-20190628-94712-x1bv35.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=515&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281852/original/file-20190628-94712-x1bv35.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=648&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281852/original/file-20190628-94712-x1bv35.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=648&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281852/original/file-20190628-94712-x1bv35.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=648&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dead zone and harmful algal bloom trends with 2019 forecasts in red.</span>
<span class="attribution"><span class="source">from http://scavia.seas.umich.edu/hypoxia-forecasts/</span></span>
</figcaption>
</figure>
<p>The main policy tool available now to combat nutrient losses from agricultural lands is the <a href="https://www.farmers.gov/farmbill">Farm Bill</a>, enacted about every five years, which provides <a href="https://theconversation.com/trump-budget-would-undo-gains-from-conservation-programs-on-farms-and-ranches-82420">funds for voluntary conservation efforts</a>. Between 1995 and 2015, the U.S. Department of Agriculture provided almost <a href="https://conservation.ewg.org/?_ga=2.138171184.145269961.1561742445-1342849811.1561742445">US$32 billion</a> in conservation incentive payments. U.S. water quality would be much worse without these programs, but they simply have not been sufficient to reduce nutrient loads over time. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/282125/original/file-20190702-105206-okzyf9.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/282125/original/file-20190702-105206-okzyf9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282125/original/file-20190702-105206-okzyf9.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=531&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282125/original/file-20190702-105206-okzyf9.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=531&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282125/original/file-20190702-105206-okzyf9.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=531&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282125/original/file-20190702-105206-okzyf9.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=667&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282125/original/file-20190702-105206-okzyf9.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=667&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282125/original/file-20190702-105206-okzyf9.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=667&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nutrient load trends; 2019 loads in red.</span>
<span class="attribution"><span class="source">From: http://scavia.seas.umich.edu/hypoxia-forecasts/</span></span>
</figcaption>
</figure>
<h2>Warmer and wetter</h2>
<p>Scientists predict that as the climate warms, this problem is <a href="http://dx.doi.org/10.1126/science.aan2409">likely to get worse</a>. </p>
<p>Most climate models forecast <a href="https://nca2018.globalchange.gov/">increased precipitation</a>, especially intense spring rains, for most of the Midwest, the Great Lakes basin and the mid-Atlantic. As air warms, it can hold increasing amounts of water vapor, which <a href="https://theconversation.com/climate-change-is-driving-rapid-shifts-between-high-and-low-water-levels-on-the-great-lakes-118095">contributes to more precipitation</a> during extreme weather events. In turn, heavier rainfall will impact nutrient runoff and dead zone formation.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/281809/original/file-20190628-94716-aeezy9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/281809/original/file-20190628-94716-aeezy9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/281809/original/file-20190628-94716-aeezy9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=465&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281809/original/file-20190628-94716-aeezy9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=465&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281809/original/file-20190628-94716-aeezy9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=465&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281809/original/file-20190628-94716-aeezy9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=585&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281809/original/file-20190628-94716-aeezy9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=585&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281809/original/file-20190628-94716-aeezy9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=585&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 a worst-case climate change scenario, in which global temperatures rise nearly 5 degrees Celsius above preindustrial levels by 2100, very heavy precipitation events in the Midwest, Great Plains and Southeast regions would increase sharply.</span>
<span class="attribution"><a class="source" href="https://www.climate.gov/sites/default/files/NCA4_heavy-precipitation-projected_large.jpg">NOAA</a></span>
</figcaption>
</figure>
<h2>A dietary strategy</h2>
<p>Farm-based conservation programs are important, and some new practices could <a href="https://doi.org/10.1016/j.ecoleng.2017.03.015">improve nutrient management</a>. For example, farmers can widen drainage ditches to create two-stage ditches, which allow water to flow onto vegetated side “benches” that capture nutrients during periods of heavy rainfall. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/282106/original/file-20190701-105187-p5m6x5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/282106/original/file-20190701-105187-p5m6x5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282106/original/file-20190701-105187-p5m6x5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=154&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282106/original/file-20190701-105187-p5m6x5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=154&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282106/original/file-20190701-105187-p5m6x5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=154&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282106/original/file-20190701-105187-p5m6x5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=194&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282106/original/file-20190701-105187-p5m6x5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=194&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282106/original/file-20190701-105187-p5m6x5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=194&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A two-stage ditch has a low-flow channel and a vegetated side ‘benches’ that are flooded during higher flows. The grass slows water flow and allows nutrients to settle out.</span>
<span class="attribution"><a class="source" href="https://agbmps.osu.edu/bmp/open-channeltwo-stage-ditch-nrcs-582">Ohio State University Extension</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>But even these measures would have to be implemented at <a href="http://dx.doi.org/10.1002/fee.1472">unprecedented scales</a> to be effective. The challenge is even more daunting when recognizing that, for example, while the annual total phosphorus load to Lake Erie is large, it is only 10% of the amount applied in fertilizer each year. In addition, as with the Chesapeake and Mississippi watersheds, soils around Lake Erie are already laden with nitrogen and phosphorus. </p>
<p>In my view, part of the solution could be using markets to <a href="https://theconversation.com/industrial-corn-farming-is-ruining-our-health-and-polluting-our-watersheds-39721">drive a shift away from industrial-scale corn production</a>, which is a major source of nutrient pollution. One major step would be eliminating the federal mandate requiring oil companies to <a href="https://www.epa.gov/renewable-fuel-standard-program/overview-renewable-fuel-standard">blend corn-based ethanol into gasoline</a>, which consumes <a href="https://www.scientificamerican.com/article/time-to-rethink-corn/">40% of U.S. corn production</a>. </p>
<p>This will be politically difficult as long as presidential primaries <a href="https://www.politico.com/magazine/story/2019/03/05/2020-democrats-ethanol-225517">start in Iowa</a>. But other strategies may be more feasible, such as encouraging private-sector companies to demand <a href="https://fieldtomarket.org/">corn raised through more sustainable practices</a>.</p>
<p><a href="https://www.wri.org/publication/creating-sustainable-food-future#main-content">Reducing meat consumption</a>, which consumes another <a href="https://www.scientificamerican.com/article/time-to-rethink-corn/">36% of U.S. corn production</a> for animal feed, could also have a significant impact. Studies have shown that reducing this demand for row crops <a href="https://doi.org/10.1016/j.ecolmodel.2015.12.001">reduces nutrient pollution</a>. </p>
<p>This idea has gained momentum with the growth of the alternative meat industry. The success of startups like <a href="https://www.beyondmeat.com/">Beyond Meat</a> and <a href="https://impossiblefoods.com/">Impossible Foods</a> is luring giants like <a href="http://fortune.com/2019/06/13/tyson-plant-based-meat-pea-protein/">Tyson</a> and <a href="https://www.channelnewsasia.com/news/business/chicken-producer-perdue-enters-crowded-plant-based-meat-market-11629576">Perdue</a> into the game. Some are even struggling to keep up with demand for plant-based meat alternatives, <a href="https://www.nytimes.com/2019/06/15/business/impossible-foods-burger-demand.html">particularly in China</a>. One recent market analysis suggests that plant-based “meat” will <a href="https://www.atkearney.com/retail/article/?/a/how-will-cultured-meat-and-meat-alternatives-disrupt-the-agricultural-and-food-industry">surpass animal sources globally by 2040</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/281824/original/file-20190628-94716-1gts8g7.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/281824/original/file-20190628-94716-1gts8g7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/281824/original/file-20190628-94716-1gts8g7.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=375&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281824/original/file-20190628-94716-1gts8g7.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=375&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281824/original/file-20190628-94716-1gts8g7.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=375&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281824/original/file-20190628-94716-1gts8g7.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=472&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281824/original/file-20190628-94716-1gts8g7.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=472&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281824/original/file-20190628-94716-1gts8g7.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=472&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.atkearney.com/retail/article/?/a/how-will-cultured-meat-and-meat-alternatives-disrupt-the-agricultural-and-food-industry">AT Kearney</a>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Shrinking agriculture’s footprint</h2>
<p>Scientists have understood for decades that excess nitrogen and phosphorus degrade Lake Erie, the Chesapeake Bay and the Gulf of Mexico. Nutrient inputs from sewage treatment plants and other discreet, easily identifiable sources have declined because they are regulated under the Clean Water Act. </p>
<p>But the nutrients fouling these water bodies now come mostly from diffuse sources, particularly industrial-scale row crop agriculture. Those operations are not subject to the Clean Water Act, and voluntary conservation programs seem to have at best kept pace with the expansion of large-scale farming. </p>
<p>After analyzing these issues and providing policy advice on them for much of my 45-year career, it’s frustrating to see so little change. But I am hopeful that current work that addresses agricultural pollution in broader contexts may have an impact. </p>
<p>For example, recent reports connecting <a href="https://doi.org/10.1016/S0140-6736(18)31788-4">reduced meat consumption</a> to both positive environmental effects and improved health should provide additional incentives for change. <a href="https://www.wri.org/publication/creating-sustainable-food-future#main-content">Research institutes</a> and <a href="https://doi.org/10.1146/annurev-environ-102017-025957">scholars</a> are laying out comprehensive global pathways to more sustainable agriculture that are designed to feed the world and protect and restore natural ecosystems. </p>
<p>My hope lies in the combination of health- and market-driven movement toward plant-based meat substitutes and enlightened policies that support more sustainable practices in agriculture’s critical role of providing food and fiber to the world.</p><img src="https://counter.theconversation.com/content/118902/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Donald Scavia has received funding from the National Science Foundation, the Environmental Protection Agency, the National Oceanic and Atmospheric Administration, Environment and Climate Change Canada, the Erb Family Foundation, the Joyce Foundation, and the C.S. Mott Foundation.</span></em></p>Scientists are predicting major algae blooms in Lake Erie and large dead zones in the Chesapeake Bay and Gulf of Mexico this summer. Nutrient pollution from industrial corn farming is a major driver.Donald Scavia, Professor Emeritus, School for Environment and Sustainability, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1062912019-01-17T11:40:02Z2019-01-17T11:40:02ZA new way to curb nitrogen pollution: Regulate fertilizer producers, not just farmers<figure><img src="https://images.theconversation.com/files/253909/original/file-20190115-152983-nchrme.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Applying nitrogen fertilizer to corn at the W.K. Kellogg Biological Station, a research site in Michigan.</span> <span class="attribution"><a class="source" href="https://www.nsf.gov/news/mmg/mmg_disp.jsp?med_id=76363&from=">NSF</a></span></figcaption></figure><p><a href="http://nora.nerc.ac.uk/id/eprint/500700/1/N500700BK.pdf">Nitrogen pollution</a> is produced by a number of interlinked compounds, from ammonia to nitrous oxide. While they have both natural and human sources, the latter increased dramatically over the past century as farmers scaled up food production in response to population growth. Once these chemicals are released into the air and water, they contribute to problems that include climate change and “dead zones” in rivers, lakes and coastal areas. </p>
<p>Reducing nitrogen pollution around the globe is an urgent environmental goal, but extremely challenging – in part because the <a href="https://www.epa.gov/nutrientpollution/sources-and-solutions-agriculture">main human source is agriculture</a>. Environmental policies are especially hard to enforce on farms because there are many of them over broad areas, which makes it difficult to confirm that farmers are complying. And powerful agricultural interest groups often <a href="https://doi.org/10.1371/journal.pbio.1002242">push back against them</a>. </p>
<p>Even for farmers who want to do a better job, managing nitrogen use is challenging. Nitrogen is a key nutrient that helps plants and livestock grow, but it <a href="https://extension.umd.edu/sites/extension.umd.edu/files/_images/programs/anmp/N_newsltr.pdf">escapes readily into the environment</a>. </p>
<p>My research focuses on <a href="https://scholar.google.com/citations?user=ne_hTA4AAAAJ&hl=en">nitrogen and its many environmental impacts</a>. In a recent study, Princeton University research scholar <a href="https://scholar.google.com/citations?user=zVkUBkIAAAAJ&hl=en">Tim Searchinger</a> and I lay out a new strategy that <a href="https://doi.org/10.1038/s41893-018-0143-8">targets fertilizer companies</a> as well as farmers. It draws from the example of <a href="https://theconversation.com/how-the-federal-government-came-to-control-your-cars-fuel-economy-94467">U.S. fuel efficiency standards</a>, which reduce fuel consumption by regulating a relatively small group of large car manufacturers instead of more than 200 million drivers. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/253924/original/file-20190115-152962-cnw0so.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253924/original/file-20190115-152962-cnw0so.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253924/original/file-20190115-152962-cnw0so.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=388&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253924/original/file-20190115-152962-cnw0so.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=388&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253924/original/file-20190115-152962-cnw0so.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=388&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253924/original/file-20190115-152962-cnw0so.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=488&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253924/original/file-20190115-152962-cnw0so.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=488&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253924/original/file-20190115-152962-cnw0so.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=488&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nutrient pollution affects waterways across the United States.</span>
<span class="attribution"><a class="source" href="https://www.epa.gov/sites/production/files/2013-08/infographic-nutrient-pollution-explained.png">USEPA</a></span>
</figcaption>
</figure>
<h2>The limits of farmer-focused policies</h2>
<p>Nitrogen is essential for producing food, but about half of the nitrogen used in the global agricultural sector – from fertilizer applied on fields to manure stored in lagoons – is either <a href="https://doi.org/10.1038/nature15743">emitted to the atmosphere or washed off into local waterways</a>. </p>
<p>These losses stem from how farmers apply nitrogen and in what forms. Consequently, most nitrogen management policies are designed to give farmers incentives to change their behavior – for example, by developing nutrient management plans or using more environmentally friendly fertilizers that delay the release of nitrogen into soil. </p>
<p>However, this approach has had little effect. At the national level, adoption of best practices and technologies has remained <a href="https://data.ers.usda.gov/reports.aspx?ID=17883">stagnant since the mid-1990s</a>, while <a href="https://yosemite.epa.gov/sab/sabproduct.nsf/WebBOARD/INCFullReport/$File/Final%20INC%20Report_8_19_11(without%20signatures).pdf">nitrogen pollution levels have increased</a> . </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/254218/original/file-20190116-163262-zhey5x.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/254218/original/file-20190116-163262-zhey5x.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/254218/original/file-20190116-163262-zhey5x.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=514&fit=crop&dpr=1 600w, https://images.theconversation.com/files/254218/original/file-20190116-163262-zhey5x.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=514&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/254218/original/file-20190116-163262-zhey5x.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=514&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/254218/original/file-20190116-163262-zhey5x.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=646&fit=crop&dpr=1 754w, https://images.theconversation.com/files/254218/original/file-20190116-163262-zhey5x.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=646&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/254218/original/file-20190116-163262-zhey5x.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=646&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Fertilizer is the single largest source of nitrogen pollution delivered downriver to the Gulf of Mexico.</span>
<span class="attribution"><a class="source" href="https://www.usgs.gov/news/challenge-tracking-nutrient-pollution-2300-miles">USGS</a></span>
</figcaption>
</figure>
<p>To get past this impasse, we looked for approaches that go beyond the farmer. Analyzing past environmental policies, we identified two conditions that increased the chances of success. First, policies tend to be more successful when they target sectors in which a small number of actors control a majority of the market, which makes monitoring and enforcement easier. The United States has <a href="https://www.nass.usda.gov/Publications/Highlights/2014/Highlights_Farms_and_Farmland.pdf">2.1 million farms spread over 900 million acres</a>, so regulating nitrogen use at the farm level is not an efficient approach.</p>
<p>Second, we found that the likelihood of success increases dramatically if the regulated actors can profit from being regulated – for example, because they produce patent-protected alternatives to the product that is being controlled.</p>
<p>The 1987 <a href="https://doi.org/10.1002/(SICI)1099-0836(199711)6:5%3C276::AID-BSE123%3E3.0.CO;2-A">Montreal Protocol</a>, which phased out chlofluorocarbons (CFCs) because they depleted Earth’s stratospheric ozone layer, is a good example. Chemical manufacturer DuPont controlled a quarter of global CFC production when the treaty was negotiated, but supported the agreement because it also had patents on at least two generations of CFC alternatives. </p>
<p>In other words, the policy created a global market for a new set of products. We believe a similar dynamic exists for the North American fertilizer industry. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/gfAInZDdyfU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Current ideas for using nitrogen more efficiently focus on getting farmers to use new techniques and tools, such as sensors.</span></figcaption>
</figure>
<h2>Profiting from better management</h2>
<p>Five companies currently control <a href="https://www.nutrien.com/sites/default/files/uploads/2018-01/Nutrien%20Fact%20Book%202018_1.pdf">over 80 percent of North American production capacity</a> for urea, an inexpensive form of nitrogen fertilizer, and ammonia, the main ingredient for all types of nitrogen fertilizers. Four of these companies either produce a more environmentally friendly fertilizer or provide a service to help farmers use nitrogen more efficiently. </p>
<p>But these greener offerings occupy a very small niche in the fertilizer market. For example, <a href="https://www.nutrien.com/">Nutrien</a>, which makes the most popular environmentally friendly fertilizer, <a href="https://www.smartnitrogen.com/">Environmentally Smart Nitrogen</a>, devotes <a href="https://www.nutrien.com/sites/default/files/uploads/2018-01/Nutrien%20Fact%20Book%202018_1.pdf">less than 5 percent</a> of its nitrogen production capacity to this product. Nor are these options widely used by farmers. </p>
<p>Effective nitrogen management policies could boost demand for these products and services. They also could stimulate development of new technologies better suited to specific crops and climates, which would represent important economic opportunities for the fertilizer industry. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"956987608055369728"}"></div></p>
<h2>Regulate the few, not the many</h2>
<p>To understand what an industry-focused approach might look like, we turned to U.S. <a href="https://www.nhtsa.gov/laws-regulations/corporate-average-fuel-economy">corporate average fuel efficiency (CAFE) standards</a>. CAFE regulations, which were introduced in response to high gas prices during the 1973 Arab oil embargo, require motor vehicle manufacturers to meet rising fuel efficiency targets over time, measured in miles per gallon for new vehicles. </p>
<p>Instead of forcing over 200 million drivers to limit their mileage, this approach targets car manufacturers and ensures that the U.S. vehicle fleet becomes more fuel-efficient over time. The Trump administration is currently seeking to <a href="https://theconversation.com/the-math-on-why-the-trump-administrations-fuel-standards-report-is-seriously-flawed-108795">freeze CAFE standards</a> instead of implementing an increase negotiated under President Obama, but it is not contesting the basic idea of making manufacturers responsible for vehicle fuel economy.</p>
<p>This approach could be applied to fertilizer in at least two ways. First, suppliers could be required to increase sales of more environmentally friendly fertilizers as a percentage of total sales. Second, their products could be required to achieve a specific performance level where more nitrogen is available to crops rather than lost to the environment.</p>
<p>Both approaches would share the burden of improving nitrogen management across farmers and the fertilizer industry. They also would give manufacturers incentive to develop more effective options.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/253927/original/file-20190115-152974-10rzn1y.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/253927/original/file-20190115-152974-10rzn1y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/253927/original/file-20190115-152974-10rzn1y.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=424&fit=crop&dpr=1 600w, https://images.theconversation.com/files/253927/original/file-20190115-152974-10rzn1y.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=424&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/253927/original/file-20190115-152974-10rzn1y.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=424&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/253927/original/file-20190115-152974-10rzn1y.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=532&fit=crop&dpr=1 754w, https://images.theconversation.com/files/253927/original/file-20190115-152974-10rzn1y.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=532&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/253927/original/file-20190115-152974-10rzn1y.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=532&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nitrogen is the most widely used agricultural fertilizer worldwide.</span>
<span class="attribution"><a class="source" href="https://ourworldindata.org/fertilizer-and-pesticides">FAO</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<h2>Benefits for farmers, industry and the environment</h2>
<p>We evaluated how such an approach could work on 25 million acres of U.S. corn farmlands <a href="https://pubag.nal.usda.gov/download/53973/PDF">where nitrogen application rates are especially excessive</a>. To estimate potential impacts, we compared three policy scenarios that required farmers to use environmentally friendly forms of nitrogen for either 12, 30 or 50 percent of their total applications by 2030. </p>
<p>In our most ambitious scenario, we calculated that farmers’ fertilizer costs would rise. However, this increase would be more than offset by higher revenue from increased corn yields, leading to total nationwide gains of US$300 million by 2030. Industry profits would increase by over $150 million during the same period due to increased sales of more environmentally friendly fertilizers, which generate higher profit margins than traditional fertilizers. And the policy would produce $8 billion in environmental benefits by 2030 due to avoided damage costs from nitrogen pollution, dwarfing the impacts on farmers and industry.</p>
<p>It would make sense to test a CAFE-style approach at the local or state level. California, which has already adopted ambitious climate change goals – including <a href="https://www.climatechange.ca.gov/state/agriculture.html">mitigating greenhouse gas emissions from agriculture</a> – could be a potential test bed.</p>
<p>There is no easy solution for curbing nitrogen pollution, given the diversity of agricultural, climatic and political systems across the world. Nevertheless, as the challenge worsens and world population grows, it is urgent to explore all policy options, especially approaches that could stimulate technological change and address a variety of environmental threats more quickly.</p><img src="https://counter.theconversation.com/content/106291/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Kanter is the Vice-Chair of the International Nitrogen Initiative.</span></em></p>Fertilizer is a key source of nitrogen pollution which fouls air and water worldwide. Current regulations target farmers, but focusing on producers could spur them to develop greener products.David Kanter, Assistant Professor of Environmental Studies, New York UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/960772018-05-04T10:49:04Z2018-05-04T10:49:04ZDead zones are a global water pollution challenge – but with sustained effort they can come back to life<figure><img src="https://images.theconversation.com/files/217590/original/file-20180503-153873-uxnbif.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Blooms of algae, like this growth in 2015 in Lake St. Clair between Michigan and Ontario, promote the formation of dead zones.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/ExAjFX">NASA Earth Observatory</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Scientists have <a href="https://doi.org/10.1029/2017GL076666">identified a dead zone</a> as large as Florida in the Gulf of Oman, which connects the Arabian Sea to the Persian Gulf. Around the world there are <a href="https://earthobservatory.nasa.gov/IOTD/view.php?id=44677">more than 400</a> current dead zones in oceans and lakes, where water contains so little oxygen that aquatic life can’t survive.</p>
<p>Dead zones form when aquatic organisms consume dissolved oxygen faster than it can be supplied. This typically happens when warmer water sits on top of colder water, or freshwater sits on top of saltier water - for example, where a river meets the sea. In either case the water on top is less dense and floats. The layers don’t mix much, so very little oxygen from the atmosphere reaches the lower layers. </p>
<p>The next ingredient is organic matter in the water. It can come from untreated sewage, or from blooms of algae, along with dead plankton and fish. This material eventually sinks into the bottom layer, where bacteria decompose it, using oxygen as fuel. This process can consume most or all of the oxygen from the water.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/217595/original/file-20180503-153881-fwfoia.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/217595/original/file-20180503-153881-fwfoia.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/217595/original/file-20180503-153881-fwfoia.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=296&fit=crop&dpr=1 600w, https://images.theconversation.com/files/217595/original/file-20180503-153881-fwfoia.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=296&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/217595/original/file-20180503-153881-fwfoia.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=296&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/217595/original/file-20180503-153881-fwfoia.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=372&fit=crop&dpr=1 754w, https://images.theconversation.com/files/217595/original/file-20180503-153881-fwfoia.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=372&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/217595/original/file-20180503-153881-fwfoia.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=372&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A massive dead zone forms in the Gulf of Mexico every year, fed by farm runoff that washes down the Mississippi River.</span>
<span class="attribution"><a class="source" href="https://www.epa.gov/sites/production/files/2017-08/4573.jpg">EPA</a></span>
</figcaption>
</figure>
<p>Temperature is also a factor. Higher temperatures promote faster algae growth, enhance formation of layers in the water, and reduce the amount of dissolved oxygen that the water can hold. <a href="http://dx.doi.org/10.5194/bg-10-2633-2013">Climate change</a> is tending to increase temperatures and make dead zones worse.</p>
<p>But the biggest driver is nutrient pollution – excess inputs of nitrogen and phosphorus. These nutrients stimulate algae growth. They come from municipal and industrial wastewater treatment plants, and increasingly from <a href="https://theconversation.com/nutrient-pollution-voluntary-steps-are-failing-to-shrink-algae-blooms-and-dead-zones-81249">fertilizer runoff from industrial-scale agriculture</a>.</p>
<p>A recent <a href="http://dx.doi.org/10.1126/science.aam7240">global-scale analysis</a> shows that oxygen-depleted zones in the open ocean have expanded by several million square kilometers since the mid-20th century, and oxygen concentrations at hundreds of coastal sites like the <a href="http://www.jstor.org/stable/24868567?seq=1#page_scan_tab_contents">Gulf of Mexico</a> are now low enough to limit the distribution and abundance of fish. These impacts are also being felt in <a href="https://doi.org/10.1073/pnas.1505815112">estuaries</a> and the <a href="https://doi.org/10.1016/j.jembe.2009.07.027">Great Lakes</a>. </p>
<p>As <a href="https://scholar.google.com/citations?user=-K4wV5QAAAAJ&hl=en">my research</a> has shown, large-scale dead zones are resistant to change. But nutrient reductions in the <a href="https://theconversation.com/cutting-pollution-in-the-chesapeake-bay-has-helped-underwater-grasses-rebound-92716">Chesapeake Bay</a> are starting to improve conditions there. Communities around Lake Erie <a href="https://www.sciencedirect.com/science/article/pii/S0380133014000252?via%3Dihub">dramatically reduced its dead zone and toxic algae blooms</a> in the 1970s by reducing phosphorus inputs. Now, however, these issues are <a href="https://www.cbsnews.com/news/toxic-algae-leads-ohio-to-designate-western-lake-erie-as-impaired/">resurfacing there</a> – evidence that this problem is an ongoing challenge.</p><img src="https://counter.theconversation.com/content/96077/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Donald Scavia received funding from the National Science Foundation, the National Oceanic and Atmospheric Administration, the Environmental Protection Agency, the Erb Family Foundation, the Joyce Foundation, and the University of Michigan's Graham Sustainability Institute. </span></em></p>Scientists have mapped a huge dead zone in the Gulf of Oman, without enough oxygen in the water to support life. This Speed Read explains why dead zones form in waters around the world.Donald Scavia, Professor Emeritus of Environment and Sustainability, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/812492017-07-31T19:23:32Z2017-07-31T19:23:32ZNutrient pollution: Voluntary steps are failing to shrink algae blooms and dead zones<figure><img src="https://images.theconversation.com/files/179716/original/file-20170725-30134-10j0n9d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Harmful algae bloom in Lake Erie, Oct. 13, 2011.</span> <span class="attribution"><a class="source" href="https://flic.kr/p/cMtuny">NASA Earth Observatory</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>Summer is the season for <a href="http://www.whoi.edu/redtide/">harmful algae blooms</a> in many U.S. lakes and bays. They occur when water bodies become overloaded with nitrogen and phosphorus from farms, water treatment plants and other sources. Warm water and lots of nutrients promote rapid growth of algae that can be toxic and potentially fatal to aquatic life and people.</p>
<p>Eventually algae settle to the bottom and decay, depleting dissolved oxygen in the water, creating <a href="http://www.smithsonianmag.com/science-nature/ocean-dead-zones-are-getting-worse-globally-due-climate-change-180953282/">hypoxia</a> – “dead zones” where oxygen levels are low enough to kill fish.</p>
<p>As a senior scientist at the National Oceanographic and Atmospheric Administration between 1975 and 2003, I developed annual hypoxia forecasts for the Chesapeake Bay and the Gulf of Mexico – two of our nation’s water bodies most harmed by these blooms. At the University of Michigan, I helped develop harmful algae bloom forecasts for Lake Erie and continue to work with public and private organizations on these issues.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/i70K0Duu-m4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">University of Michigan professor Donald Scavia discusses the 2015 forecasts.</span></figcaption>
</figure>
<p>States around Lake Erie and in the Mississippi River basin, which drains to the Gulf of Mexico, have been trying to reduce nutrient pollution for years. They rely primarily on voluntary steps, such as offering grants to farmers to take steps to prevent fertilizer from washing off their fields.</p>
<p>In contrast, states around the Chesapeake have had more success with a federally enforced plan that can impose mandatory actions across the bay’s 64,000-square-mile watershed. From my perspective, when we compare these two approaches it is clear that voluntary measures are not even making modest dents in nutrient pollution. </p>
<h2>This year’s forecasts</h2>
<p>This year’s <a href="http://ns.umich.edu/new/releases/24961-u-m-partners-predict-significant-summer-harmful-algal-bloom-for-western-lake-erie">Lake Erie harmful algae bloom forecast</a> has a severity index of 7.5 on a scale of 1 to 10. This is comparable to the three largest blooms since 2011, including one that <a href="https://www.facebook.com/cityoftoledo/posts/738905586173078">made the city of Toledo’s tap water unusable</a> for three days in 2014. The algae produced microcystin – a toxin that can produce effects <a href="https://www.epa.gov/nutrient-policy-data/health-and-ecological-effects">from mild skin rashes to serious illness or death</a>.</p>
<p>The <a href="http://ns.umich.edu/new/releases/24919-u-michigan-partners-predict-third-largest-gulf-of-mexico-summer-dead-zone-ever">Gulf of Mexico forecast</a> predicts an 8,185-square-mile dead zone – more than four times the goal set by an <a href="https://www.epa.gov/ms-htf">intergovernmental task force</a>. This will be the third-largest Gulf of Mexico dead zone since measurements began 32 years ago.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/180054/original/file-20170727-8492-q4n7dr.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/180054/original/file-20170727-8492-q4n7dr.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/180054/original/file-20170727-8492-q4n7dr.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=662&fit=crop&dpr=1 600w, https://images.theconversation.com/files/180054/original/file-20170727-8492-q4n7dr.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=662&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/180054/original/file-20170727-8492-q4n7dr.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=662&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/180054/original/file-20170727-8492-q4n7dr.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=832&fit=crop&dpr=1 754w, https://images.theconversation.com/files/180054/original/file-20170727-8492-q4n7dr.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=832&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/180054/original/file-20170727-8492-q4n7dr.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=832&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Chesapeake Bay watershed covers more than 64,000 square miles in parts of six states and the District of Columbia.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Chesapeake_Bay#/media/File:Chesapeakewatershedmap.png">Kmusser</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The <a href="http://ns.umich.edu/new/releases/24900-larger-than-average-summer-dead-zone-predicted-for-chesapeake-bay-in-2017">Chesapeake forecast</a> predicts a 1.9-cubic-mile hypoxic region – nearly the volume of 3.2 million Olympic-size swimming pools. This is much larger than goals reflected in recent policies. </p>
<p>Nonetheless, at least the Chesapeake is moving in the right direction. The amount of nutrients flowing into the bay is starting to decline.</p>
<h2>The long quest to clean up Lake Erie</h2>
<p>Lake Erie first suffered from heavy nutrient pollution in the 1960s. The Clean Water Act of 1972 triggered a remarkable cleanup. Nutrients, primarily from point (discreet) sources like sewage treatment plants, were cut in half, and the <a href="http://graham.umich.edu/scavia/wp-content/uploads/2009/11/Scavia-et-al-20142.pdf">lake responded quickly</a>.</p>
<p>But harmful algae blooms and hypoxia <a href="http://graham.umich.edu/scavia/wp-content/uploads/2009/11/Scavia-et-al-20142.pdf">resurfaced in the mid-1990s</a>, probably because flows into the lake of a form of phosphorus that is readily used by algae tripled. The dead zone set a <a href="http://dx.doi.org/10.1021/es503981n">new record in 2012</a>, and harmful algae blooms <a href="http://graham.umich.edu/scavia/wp-content/uploads/2013/04/PNAS.pdf">set records in 2011</a> and 2015. Even if blooms do not become toxic, they can have devastating effects. For example, the 2011 harmful algae blooms on Lake Erie cost the region <a href="http://www.ijc.org/en_/blog/2015/12/17/economic_benefits_of_reducing_HABs/">nearly US$71 million</a> in diminished property values, water treatment, and lost tourism revenues and recreational opportunities.</p>
<p>In response, the United States and Canada negotiated new <a href="https://binational.net/2016/02/22/finalptargets-ciblesfinalesdep/">phosphorus loading targets</a> that call for a 40 percent reduction from 2008 levels. Ontario, Ohio, Michigan, Indiana, Pennsylvania and New York are developing <a href="https://binational.net/2017/03/10/dap-pan/">domestic action plans</a> to meet those targets. </p>
<p>Now however, 71 percent of nutrients entering Lake Erie are from <a href="https://doi.org/10.1016/j.jglr.2016.08.005">non-point sources</a> – mainly from <a href="http://dx.doi.org/10.1111/j.1752-1688.2011.00574.x">agriculture</a>. Non-point source pollution comes from diffuse sources, such as fertilizer washing off of farms and lawns, so it is harder to control. </p>
<p>The United States contributes over 80 percent of Lake Erie’s total phosphorus load. In sum, major load reductions will have to come from agriculture, mostly from U.S. farms. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/180251/original/file-20170728-5295-12pnaz8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/180251/original/file-20170728-5295-12pnaz8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/180251/original/file-20170728-5295-12pnaz8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=310&fit=crop&dpr=1 600w, https://images.theconversation.com/files/180251/original/file-20170728-5295-12pnaz8.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=310&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/180251/original/file-20170728-5295-12pnaz8.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=310&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/180251/original/file-20170728-5295-12pnaz8.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=389&fit=crop&dpr=1 754w, https://images.theconversation.com/files/180251/original/file-20170728-5295-12pnaz8.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=389&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/180251/original/file-20170728-5295-12pnaz8.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=389&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Phosphorus loads to Lake Erie.</span>
<span class="attribution"><span class="source">[Maccoux et al. Journal of Great Lakes Research 42 (2016) 1151–1165](https://doi.org/10.1016/j.jglr.2016.08.005)</span></span>
</figcaption>
</figure>
<h2>How effective are voluntary measures?</h2>
<p>Governments generally are averse to imposing environmental regulations on farmland. As a result, most action plans for Lake Erie rely on voluntary, incentive-based programs to address nutrient loss from agricultural lands.</p>
<p>But in the Mississippi River basin this approach has failed. In spite of more than 30 years of research and monitoring, over 15 years of <a href="http://tinyurl.com/zju939n;">assessments and goal-setting</a>, and <a href="http://graham.umich.edu/scavia/farm-bill-conservation-funding-1995-2015/">over US$30 billion</a> in federal conservation funding since 1995, average nitrogen levels in the Mississippi <a href="https://pubs.er.usgs.gov/publication/sir20135169">have not declined since the 1980s</a>.</p>
<p>The <a href="https://www.epa.gov/ms-htf">task force</a> leading this effort recently extended the deadline for its goal of a <a href="http://tinyurl.com/j5rvfqk">1,930-square-mile</a> dead zone from 2015 to 2035. Today the dead zone is <a href="http://www.gulfhypoxia.net/Research/">more than triple that size</a>. Our <a href="http://www.pnas.org/content/early/2017/07/27/1705293114">newly published modeling</a>
shows that it would take a 59 percent reduction in the amount of nitrogen entering the Gulf of Mexico to reach the task force’s goal. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/178883/original/file-20170719-13567-cdeeds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/178883/original/file-20170719-13567-cdeeds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=326&fit=crop&dpr=1 600w, https://images.theconversation.com/files/178883/original/file-20170719-13567-cdeeds.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=326&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/178883/original/file-20170719-13567-cdeeds.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=326&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/178883/original/file-20170719-13567-cdeeds.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=410&fit=crop&dpr=1 754w, https://images.theconversation.com/files/178883/original/file-20170719-13567-cdeeds.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=410&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/178883/original/file-20170719-13567-cdeeds.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=410&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dissolved oxygen levels in the Gulf of Mexico in summer 2010.</span>
<span class="attribution"><a class="source" href="http://www.noaanews.noaa.gov/stories2010/20100809_deadzone.html">NOAA</a></span>
</figcaption>
</figure>
<h2>The Chesapeake Bay’s pollution diet</h2>
<p>States around the Chesapeake Bay also struggled for decades to make voluntary, incentive-based approaches work. Their efforts were overwhelmed by the impacts of population growth and agricultural production. </p>
<p>Frustrated by worsening conditions, the states asked EPA in 2010 to establish a <a href="http://www.chesapeakebay.net/what/programs/total_maximum_daily_load">total maximum daily load</a> – a <a href="https://www.epa.gov/chesapeake-bay-tmdl">“pollution diet”</a> within a regulatory framework under the Clean Water Act that limits the amount of nutrients and sediment that can enter the bay. Bay states and the District of Columbia then developed <a href="http://www.chesapeakebay.net/about/programs/watershed">implementation plans</a> and <a href="http://www.chesapeakebay.net/managementstrategies">management strategies</a> detailing how and when each jurisdiction would meet its individual goals. </p>
<p>Unlike voluntary strategies, this approach has teeth. If states miss interim milestones for reducing pollutants, EPA can impose <a href="https://www.epa.gov/sites/production/files/2014-12/documents/cbay_final_tmdl_section_7_final_0.pdf">“backstop measures</a>,” such as requiring additional reductions from point sources and withholding federal grant money. </p>
<p>Agricultural groups, <a href="http://www.cbf.org/how-we-save-the-bay/chesapeake-clean-water-blueprint/21-states-oppose-clean-water-for-chesapeake-bay-states.html">supported by 21 states outside the Chesapeake watershed</a>, challenged the total maximum daily load in court but <a href="http://www.chesapeakebay.net/blog/post/court_upholds_chesapeake_bay_pollution_diet">lost</a>. Between 2009 and 2015, loads of nitrogen, phosphorus and sediment in the bay dropped by <a href="http://www.chesapeakebay.net/documents/2015-2016_Bay_Barometer.pdf">8 percent, 20 percent and 7 percent</a>, respectively. Underwater grasses and the bay’s iconic blue crabs are <a href="http://www.cbf.org/about-the-bay/state-of-the-bay-report/2016/index.html?referrer=https://www.google.com/">starting to recover</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/180059/original/file-20170727-9209-g1jo2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/180059/original/file-20170727-9209-g1jo2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/180059/original/file-20170727-9209-g1jo2g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/180059/original/file-20170727-9209-g1jo2g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/180059/original/file-20170727-9209-g1jo2g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/180059/original/file-20170727-9209-g1jo2g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/180059/original/file-20170727-9209-g1jo2g.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">The Chesapeake Bay’s $100 million blue crab fishery is starting to recover after years of decline due mainly to water pollution.</span>
<span class="attribution"><a class="source" href="https://flic.kr/p/p2tSVr">Chesapeake Bay Program</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>No diet for Lake Erie</h2>
<p>Environmental groups recently <a href="http://greatlakesecho.org/2017/05/03/environmental-groups-sue-epa-over-condition-of-lake-erie/">sued EPA</a> to force stronger action on nutrient pollution in Lake Erie’s western basin, with support from <a href="https://kaptur.house.gov/media-center/press-releases/effort-combat-declining-water-quality-lake-erie-dingell-kaptur-urge-epa">several members of Congress</a> and the <a href="http://www.ijc.org/en_/leep/report">International Joint Commission</a>, which coordinates efforts by the United States and Canada. But EPA will apparently write a total maximum daily load only if both Michigan and Ohio, the two key states in the western basin watershed, agree. (EPA Administrator Scott Pruitt endorsed the Chesapeake Bay total maximum daily load only <a href="https://www.c-span.org/video/?c4648350/scott-pruitt-tmdl">because all six states in the bay’s watershed supported it</a>.) </p>
<p>Michigan recently <a href="http://www.mlive.com/news/index.ssf/2017/06/jamie_clover_adams_lake_erie.html">declared its portion of Lake Erie “impaired</a>,” which is required to trigger a total maximum daily load. But Ohio declared only some of its shorelines impaired, and <a href="https://www.usnews.com/news/best-states/ohio/articles/2017-05-23/epa-rejects-declaring-lake-eries-waters-in-ohio-impaired">EPA concurred</a>. So prospects for a recovery are slim.</p>
<p>EPA’s web page calls nutrient pollution one of America’s <a href="https://www.epa.gov/nutrientpollution/problem">“most widespread, costly and challenging environmental problems</a>.” But voluntary action is not solving it. And President Trump’s EPA budget request would <a href="http://www.politico.com/tipsheets/morning-agriculture/2017/05/24/ag-gets-dismissed-by-trump-220482">cut $165 million</a> in grants to states to deal with non-point source pollution. </p>
<p>As I have <a href="https://theconversation.com/industrial-corn-farming-is-ruining-our-health-and-polluting-our-watersheds-39721">detailed before</a>, taming nutrient pollution will require a broad national approach that includes steps such as modifying the American diet, changing agricultural supply chains and reducing production of corn-based ethanol. We also need to find the will to set legally binding limits when voluntary steps aren’t enough.</p><img src="https://counter.theconversation.com/content/81249/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Donald Scavia receives funding from the National Science Foundation, National Oceanic and Atmospheric Administration,
Environmental Protection Agency, and the Erb Family Foundation. </span></em></p>Nitrogen and phosphorus are polluting US waters, creating algae blooms and dead zones. New research confirms that voluntary steps are failing in the Gulf of Mexico and unlikely to work in Lake Erie.Donald Scavia, Professor of Environment and Sustainability; Professor of Environmental Engineering, University of MichiganLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/588522016-07-06T01:05:14Z2016-07-06T01:05:14ZReducing water pollution with microbes and wood chips<figure><img src="https://images.theconversation.com/files/129012/original/image-20160701-18321-znh4zj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Harmful algal bloom caused by nutrient pollution, Assateague island National Seashore, MD</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/usepagov/9324594954/in/album-72157634706332559/">Eric Vance, U.S. EPA/Flickr</a></span></figcaption></figure><p>Beneath fields of corn and soybeans across the U.S. Midwest lies an unseen network of underground pipes. These systems, which are known as <a href="http://www.extension.umn.edu/agriculture/water/planning-a-subsurface-drainage-system/">tile drainage networks</a>, channel excess water out of soil and carry it to lakes, streams and rivers. There are <a href="http://pdf.wri.org/assessing_farm_drainage.pdf">over 38 million acres</a> of tile drainage in the Corn Belt states.</p>
<p>These networks play a vital role in farm production. They allow farmers to drive tractors into fields that would otherwise be too wet and make it possible to plant early in spring. And they boost crop growth and yield by preventing fields from becoming waterlogged. </p>
<p>But drainage systems are also major contributors to water pollution. The water they remove from fields contains nitrogen, which comes both from organic matter in rich Midwestern soil and from fertilizer. This nitrogen over-fertilizes downstream water bodies, causing blooms of algae. When the algae die, bacteria decompose them, using oxygen in the water as fuel. </p>
<p>The result is hypoxic zones, also known as dead zones, where nothing can live. Some of these zones, such as the one that forms in the Gulf of Mexico every year fed by Midwestern farm drainage water, cover thousands of miles.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/129013/original/image-20160701-18334-1wnc55c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/129013/original/image-20160701-18334-1wnc55c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/129013/original/image-20160701-18334-1wnc55c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/129013/original/image-20160701-18334-1wnc55c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/129013/original/image-20160701-18334-1wnc55c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=583&fit=crop&dpr=1 754w, https://images.theconversation.com/files/129013/original/image-20160701-18334-1wnc55c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=583&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/129013/original/image-20160701-18334-1wnc55c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=583&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Gulf of Mexico dead zone forms every summer, fed by drainage from midwestern farms.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Dead_zone_(ecology)#/media/File:Dead_Zone_NASA_NOAA.jpg">NASA/NOAA via Wikipedia</a></span>
</figcaption>
</figure>
<p>Across the Midwest and in many other areas, we need to reduce nitrogen pollution on a very large scale to improve water quality. My research focuses on woodchip bioreactors – simple trenches that can be constructed on farms to clean the water that flows out of tile drains. This is a proven practice that is ready for broad-scale implementation. Nevertheless, there is still great potential to improve how well wood chip bioreactors work, and to convince farmers to use them through additional research and engagement. </p>
<h2>Removing nitrogen from farm runoff</h2>
<p>Researchers studying ways to improve agricultural water quality have <a href="https://store.extension.iastate.edu/Product/Woodchip-Bioreactors-for-Nitrate-in-Agricultural-Drainage">shown</a> that we can use a natural process called denitrification to treat subsurface drainage water on farms. It relies on bacteria found in soil around the world to convert nitrate – the form of nitrogen in farm drainage water – to nitrogen gas, which is environmentally benign and makes up more than three-fourths of the air we breathe. </p>
<p>These bacteria use carbon as a food source. In oxygen-free conditions, such as wetlands or soggy soils, they are fueled by carbon in the surrounding soil, and inhale nitrate while exhaling nitrogen gas. Bioreactors are engineered environments that take advantage of their work on a large scale.</p>
<p>Denitrifying bioreactors on farms are surprisingly simple. To make them we dig trenches between farm fields and the outlets where water flows from tile drains into ditches or streams. We fill them with wood chips, which are colonized by native bacteria from the surrounding soil, and then route water from farm drainage systems through the trenches. The bacteria “eat” the carbon in the wood chips, “inhale” the nitrate in the water, and “exhale” nitrogen gas. In the process, they reduce nitrogen pollution in water flowing off of the farm by anywhere from 15 percent to over 90 percent.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/124405/original/image-20160529-879-7xejt3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124405/original/image-20160529-879-7xejt3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=465&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124405/original/image-20160529-879-7xejt3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=465&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124405/original/image-20160529-879-7xejt3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=465&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124405/original/image-20160529-879-7xejt3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=584&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124405/original/image-20160529-879-7xejt3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=584&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124405/original/image-20160529-879-7xejt3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=584&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A denitrifying woodchip bioreactor removing nitrate from a tile-drained corn field.</span>
<span class="attribution"><span class="source">Christianson and Helmers/Iowa State Extension</span></span>
</figcaption>
</figure>
<p>Although denitrifying bioreactors are relatively new, they have moved beyond proof of concept. A new <a href="https://dl.sciencesocieties.org/publications/jeq/tocs/45/3#h1-SPECIAL%20SECTION:%20MOVING%20DENITRIFYING%20BIOREACTORS%20BEYOND%20PROOF%20OF%20CONCEPT">special collection of papers in the Journal of Environmental Quality</a>, which I co-edited with <a href="http://sci.waikato.ac.nz/about-us/people/schipper">Dr. Louis Schipper</a> of the <a href="http://www.waikato.ac.nz/">University of Waikato</a> in New Zealand, demonstrates that these systems can now be considered an effective tool to reduce pollution in nitrate-laden waters. Researchers are using these systems in an expanding range of locations, applications, and environmental conditions.</p>
<h2>Making bioreactors work for farmers</h2>
<p>Woodchip bioreactors can be installed without requiring farmers to take land out of production, and require very little annual maintenance. These are important selling points for farmers. The Clean Water Act <a href="http://ehp.niehs.nih.gov/122-a304/">does not regulate</a> nitrogen pollution from diffuse agricultural sources such as farm runoff, but states across the Midwest are working with federal regulators to set <a href="https://www.epa.gov/nutrient-policy-data/state-development-numeric-criteria-nitrogen-and-phosphorus-pollution">targets for reducing nitrogen pollution</a>. They also are developing <a href="https://www.epa.gov/ms-htf/hypoxia-task-force-nutrient-reduction-strategies">water quality strategies</a> that call for installing tens of thousands of denitrifying bioreactors to help reach those targets. </p>
<p>So far, wood chips have proven to be the most practical bioreactor fill. Research at the lab scale has also analyzed the idea of using farm residues such as corn cobs instead. In laboratory studies, such <a href="http://dx.doi.org/10.2134/jeq2015.07.0407">agricultural residues consistently provide much higher nitrate removal rates than wood chips</a>. However, they need to be replaced more frequently than wood chips, which have an estimated design life of 10 years in a bioreactor. </p>
<p>Laboratory studies have also helped us understand how <a href="http://dx.doi.org/10.2134/jeq2015.07.0399">other factors</a> influence nitrate removal in bioreactors, including water temperature and the length of time that water remains inside the bioreactor – which, in turn, depends on the flow rate and the size of the bioreactor. Another challenge is that bioreactors work best in late summer, when drainage flow rates are low and the water flowing from fields is warm, but most nitrogen flows from fields in drainage water in spring, when conditions are cool and wet. Researchers are working to design bioreactors that can overcome this disconnect. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/124406/original/image-20160529-859-la586a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/124406/original/image-20160529-859-la586a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=439&fit=crop&dpr=1 600w, https://images.theconversation.com/files/124406/original/image-20160529-859-la586a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=439&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/124406/original/image-20160529-859-la586a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=439&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/124406/original/image-20160529-859-la586a.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=552&fit=crop&dpr=1 754w, https://images.theconversation.com/files/124406/original/image-20160529-859-la586a.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=552&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/124406/original/image-20160529-859-la586a.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=552&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Installing a denitrifying woodchip bioreactor.</span>
<span class="attribution"><span class="source">L. Christianson /Iowa Soybean Association Environmental Programs and Services</span></span>
</figcaption>
</figure>
<p>We have also carried out tests to see whether bioreactors can treat <a href="http://dx.doi.org/10.2134/jeq2015.05.0242">aquaculture wastewater</a>, which typically contains much higher levels of nitrate and other water pollutants than tile drainage water. Our study showed that bioreactors could be a viable low-cost water treatment option for fish farms. </p>
<p>And researchers from New Zealand recently showed that denitrifying bioreactors may be an effective option for treating some small sources of municipal wastewater. <a href="http://dx.doi.org/10.2134/jeq2015.06.0326">Their work</a> provided the first indication that woodchip bioreactors may be able to remove microbial contaminants like E.coli and viruses, which can be hazardous to human health, from water. The exact process by which the E.coli and viruses were removed is not yet known. </p>
<p>One difficult challenge in designing denitrifying bioreactors is testing novel designs at the field scale. We need to build and test large bioreactors so that we can provide useful information to farmers, landowners, crop advisors, drainage contractors, conservation staff, and state and federal agencies. They want to know practical facts, such as how long the wood chips last (approximately 7-15 years), how much it costs to install a field-scale bioreactor ($8,000-$12,000), and whether bioreactors back up water in tile drainage systems (no). To refine what we know, we plan to continue installing full-size bioreactors either on research farms or by collaborating with private farmers who want to be at the cutting edge of water-quality solutions. </p>
<p>We all play a role in agriculture because we all eat, and at the same time, we all need clean water. Simple technologies like woodchip bioreactors can help meet both goals by helping farmers maintain good drainage and providing cleaner water downstream.</p><img src="https://counter.theconversation.com/content/58852/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Laura Christianson receives funding from the Illinois Nutrient Research and Education Council. </span></em></p>Excess nutrients from farm fields cause widespread water pollution across the U.S. Bioreactors – essentially, ditches filled with wood chips – are emerging as a way to reduce nutrient pollution.Laura Christianson, Research Assistant Professor of Crop Sciences, University of Illinois at Urbana-ChampaignLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/479842016-01-28T12:40:45Z2016-01-28T12:40:45ZAncient ‘dead seas’ offer a stark warning for our own near future<figure><img src="https://images.theconversation.com/files/109484/original/image-20160128-3064-n0f121.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">Esteban De Armas / shutterstock.com</span></span></figcaption></figure><p>For billions of years, life on Earth remained relatively simple. Only single-celled organisms that could live with little or no oxygen were able to survive in the seas. </p>
<p>Eventually, the rise of oxygen led to a proliferation of diverse, multicellular life. However the oceans have not remained unchanged since that chemical and biological revolution. At several times in geological history, they have partially reverted back to their original bacterially-dominated, oxygen-free state – and they could do so again.</p>
<p>Today rising CO<sub>2</sub> levels are making the oceans warmer and more acidic. Deforestation and intensive farming are causing soils and nutrients to be flushed into the sea. And increasingly, the oceans are being <a href="http://news.nationalgeographic.com/2015/03/150313-oceans-marine-life-climate-change-acidification-oxygen-fish/?sf7992800=1">stripped of oxygen</a>, leaving large “<a href="http://www.noaanews.noaa.gov/stories2015/080415-gulf-of-mexico-dead-zone-above-average.html">dead zones</a>” in the Gulf of Mexico, the Baltic Sea and <a href="http://www.scienceworldreport.com/articles/24972/20150430/massive-dead-zones-discovered-moving-west-north-atlantic-waters.htm">the Atlantic off West Africa</a>. </p>
<p>These dead zones, smaller-scale revivals of the primeval oceans that existed before complex life, appear to be caused by poor land management, such as <a href="http://www.scientificamerican.com/article/fertilizer-runoff-overwhelms-streams/">fertilisers draining from farms</a> into the sea. It is a process that could be exacerbated by climate change – as has happened in the past.</p>
<h2>How oceans become ‘dead’</h2>
<p>Oceans lose their oxygen when animals and bacteria consume it faster than it can be replenished. This usually comes about in stagnant or algae-rich waters.</p>
<p>In severe cases, all oxygen can be consumed rendering the waters “anoxic” and inhospitable to animal life. This happens today in isolated <a href="http://www.sciencedirect.com/science/article/pii/019801498790046X">fjords and basins</a>. And it has happened on a larger scale throughout Earth’s history, especially during the Cretaceous, towards the end of the dinosaur era 145-66m years ago. Then, large parts of the ancient oceans became anoxic, allowing vast amounts of organic matter to escape degradation, and in many cases forming <a href="http://onlinelibrary.wiley.com/doi/10.1029/2009GC002788/abstract">deposits of oil and gas</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/109488/original/image-20160128-3027-1dxzbu3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/109488/original/image-20160128-3027-1dxzbu3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/109488/original/image-20160128-3027-1dxzbu3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/109488/original/image-20160128-3027-1dxzbu3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/109488/original/image-20160128-3027-1dxzbu3.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/109488/original/image-20160128-3027-1dxzbu3.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/109488/original/image-20160128-3027-1dxzbu3.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/109488/original/image-20160128-3027-1dxzbu3.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">Hood Canal (actually a fjord) in Washington state, US, often suffers from dead zones.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Hood_Canal_07771.JPG">Walter Siegmund</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>We can examine the extent of anoxia by looking for a certain type of “<a href="http://www.els.net/WileyCDA/ElsArticle/refId-a0000458.html">green sulfur bacteria</a>” which require both sunlight and oxygen-depleted waters in order to conduct their rather <a href="http://www.ncbi.nlm.nih.gov/pubmed/11540925">exotic form of photosynthesis</a>. Evidence of their presence can be found in ancient rocks – molecular proof that anoxia once extended from the seafloor almost all the way to the ocean’s surface.</p>
<p>These oceans thrived with microbial life. But animals need oxygen, and vast portions of these ancient oceans would have become “dead” to them.</p>
<h2>Life in the deep sea</h2>
<p>Unlike almost every other ecosystem on our planet, the deep sea is bereft of light and plants. Animals down there largely live off <a href="http://oceanservice.noaa.gov/facts/marinesnow.html">marine snow</a>, the scraps of organic matter that somehow escape from the surface world and sink to the twilight realm below. In this energy-starved world, creatures live solitary lives in emptiness, darkness <a href="http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0010223">and mystery</a>. </p>
<p>And yet life is there. Krill thrive on the slowly-sinking snow. Sperm whales dive deep to consume the krill and emerge with scars from giant squid. And when a whale dies and <a href="http://discovermagazine.com/2013/september/16-deep-sea-secrets">its carcass plummets to the seafloor</a>, it is set upon by sharks and fish who emerge from the darkness for the unexpected feast. Within days the carcass is stripped to the bones – but even then, massive colonies of tube worms spring to life. </p>
<p>All of these animals, the fish, whales and worms, depend on oxygen. Our oxygen-rich seas are an incredible contrast to the North Atlantic during some anoxic events. Then, plesiosaurs (pictured at the top) and ichthyosaurs, feeding on magnificent ammonites, would have been confined to the sunlit, oxygen-rich realm near the surface, their maximum depth of descent marked by a layer of pink and then green water, pigmented by bacteria. And below it, where the deeper waters were anoxic, only single-celled organisms.</p>
<h2>Could this happen again?</h2>
<p>Conventional wisdom has been that such extreme anoxia in the future is unlikely, that Cretaceous “dead zones” were a consequence of a markedly different geography. The ancient Atlantic Ocean was smaller and more restricted, lending itself to these extreme conditions. This is a bit like <a href="http://www.ocean.washington.edu/people/faculty/jmurray/BlackSeaOverview.pdf">the modern Black Sea</a>, a restricted basin where fresh river water sits stably above salty and dense marine deep water. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/109494/original/image-20160128-3072-1v479x2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/109494/original/image-20160128-3072-1v479x2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/109494/original/image-20160128-3072-1v479x2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/109494/original/image-20160128-3072-1v479x2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/109494/original/image-20160128-3072-1v479x2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/109494/original/image-20160128-3072-1v479x2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/109494/original/image-20160128-3072-1v479x2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/109494/original/image-20160128-3072-1v479x2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">During the Cretaceous the Atlantic Ocean was much smaller.</span>
<span class="attribution"><a class="source" href="http://jan.ucc.nau.edu/~rcb7/globaltext2.html">Ron Blakey, NAU</a></span>
</figcaption>
</figure>
<p>But the Black Sea doesn’t quite match up with what we know about ancient anoxic oceans. For a start, if driven solely by geographical shape, why were the oceans not anoxic as the norm rather than only at certain times? Sometimes much larger oceans became dead zones, or the <a href="http://www.sciencedirect.com/science/article/pii/S0031018215001534">anoxia was restricted to coastal areas</a>. And although ocean circulation was slower during warm climates, it did not stop – unlike in the Black Sea.</p>
<p>This suggests geography was important but not exclusively so. Algal blooms are a more likely trigger. These algae would have flourished after dramatic <a href="http://onlinelibrary.wiley.com/store/10.1029/2009GC002788/asset/ggge1646.pdf?v=1&t=ifqwy8gh&s=fe1744cb76f35d3f4e0ae7dc8fefe456700c36fb">increases in nutrients</a> caused by erosion and chemical weathering, driven by higher carbon dioxide concentrations, global warming and/or changes in the hydrological cycle – all of which we now know occurred <a href="http://www.nature.com/ngeo/journal/v6/n8/full/ngeo1875.html">prior to several anoxic events</a>.</p>
<p>It is likely that today’s coastal dead zones are due not to climate change but to our <a href="http://www.nine-esf.org/sites/nine-esf.org/files/ena_doc/ENA_pdfs/ENA_c17.pdf">excessive use of fertilisers</a>. And it is unlikely that our future will revisit the widespread ocean anoxia of the past. But the lessons of the past do suggest global warming could exacerbate the impacts of our poor land management, adding yet another pressure to already stressed ecosystems.</p>
<hr>
<p>A longer version of Richard Pancost’s article appears on the <a href="http://cabot-institute.blogspot.co.uk/2016/01/ancient-dead-seas-offer-stark-warning.html">Cabot Institute blog</a>.</p><img src="https://counter.theconversation.com/content/47984/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Richard Pancost receives funding from Research Councils UK, the European Union and the American Chemical Society, the Leverhulme Trust and philanthropic donations to the University of Bristol.</span></em></p>Too much fertiliser can kill all life in parts of the ocean. It has happened before – and could do so again.Richard Pancost, Professor of Biogeochemistry, Director of the Cabot Institute, University of BristolLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/437472015-07-14T10:09:10Z2015-07-14T10:09:10ZForecasting dead zones and toxic algae in US waterways: a bad year for Lake Erie<figure><img src="https://images.theconversation.com/files/86273/original/image-20150624-31507-bfg9ub.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Algae overload: Lake Erie algal bloom 2011.</span> <span class="attribution"><span class="source">NOAA/NASA</span></span></figcaption></figure><p>Over the <a href="http://www.sciencemag.org/content/293/5530/657">past two decades</a>, scientists have developed ways to predict how ecosystems will react to changing environmental conditions. Called <a href="http://www.graham.umich.edu/scavia/wp-content/uploads/2009/11/cenr_ecologicalforecasting.pdf">ecological forecasts</a>, these emerging tools, if used effectively, can help reduce pollution to our waterways. </p>
<p>Dead zone and toxic algae forecasts are similar to weather and climate forecasts. They can provide near-term predictions of ecosystem responses to short-term drivers such as this year’s nitrogen and phosphorus inputs. They can also be used in scenarios to analyze the impacts of controlling those drivers in the future. </p>
<p>These particular forecasts are important because when they match actual events well, they build confidence in using the models to guide policy and management decisions. Doing these forecasts annually also provides a regular check on whether these problems are being resolved. </p>
<p>While knowing the extent and location of these ecosystem conditions could allow decision-makers to adapt their management decisions, current ecological forecasts – at least those related to dead zones and toxic algae – are not sufficiently tuned in space and time to support that scale of adaptive management. Hopefully, someday they will be. In the meantime, their use provides powerful reminders of unsolved problems.</p>
<h2>This year’s eco-forecast</h2>
<p>Dead zones (hypoxia) are regions within lakes and oceans where oxygen concentrations drop to levels dangerous to marine life. They’re typically caused by decomposing algae, the growth of which is stimulated by nitrogen and phosphorus inputs from land. Toxic algae, also stimulated by these same excess nutrients, can poison aquatic life and humans when they contaminate the water supply. </p>
<p>In recent weeks, I contributed <a href="http://graham.umich.edu/scavia/hypoxia-forecasts">predictions</a> to <a href="http://oceanservice.noaa.gov/ecoforecasting/">NOAA’s</a> ensemble forecasts of this year’s dead zones in the <a href="http://ns.umich.edu/new/multimedia/videos/22957-average-dead-zone-for-gulf-of-mexico-in-2015-u-m-and-partners-predict">Gulf of Mexico</a> and the <a href="http://ns.umich.edu/new/releases/22975-below-average-dead-zone-predicted-for-chesapeake-bay-in-2015">Chesapeake Bay</a>, and the extent of <a href="http://ns.umich.edu/new/multimedia/videos/23004-u-m-partners-predict-severe-harmful-algae-bloom-for-lake-erie">toxic algae in Lake Erie</a>. </p>
<p>The 2015 forecasts remind us that these persistent problems are not yet being addressed effectively. While the dead zone forecasts are for roughly “average” conditions, it is important to note that “average” does not mean natural, and in these cases, “average” is not acceptable. The toxic algae forecast is a clear reminder that long-term nutrient input reduction is critical.</p>
<p><strong>Gulf of Mexico</strong> - In its <a href="http://www.graham.umich.edu/scavia/wp-content/uploads/2009/11/action_20plan_1_.pdf">2001 action plan</a> – confirmed in <a href="http://water.epa.gov/type/watersheds/named/msbasin/upload/2008_8_28_msbasin_ghap2008_update082608.pdf">2008</a> and again in <a href="http://water.epa.gov/type/watersheds/named/msbasin/upload/hypoxia_reassessment_508.pdf">2013</a> – the federal, state and tribal Mississippi River/Gulf of Mexico Watershed Nutrient Task Force set a goal of reducing the five-year running average extent of gulf hypoxia, or oxygen deficiency, to 5,000 square kilometers (1930 square miles) by 2015. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/86165/original/image-20150623-19374-gps1jz.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/86165/original/image-20150623-19374-gps1jz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/86165/original/image-20150623-19374-gps1jz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=335&fit=crop&dpr=1 600w, https://images.theconversation.com/files/86165/original/image-20150623-19374-gps1jz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=335&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/86165/original/image-20150623-19374-gps1jz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=335&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/86165/original/image-20150623-19374-gps1jz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=421&fit=crop&dpr=1 754w, https://images.theconversation.com/files/86165/original/image-20150623-19374-gps1jz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=421&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/86165/original/image-20150623-19374-gps1jz.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=421&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Gulf of Mexico nitrogen loads.</span>
<span class="attribution"><a class="source" href="http://graham.umich.edu/scavia/hypoxia-forecasts/">Donald Scavia</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>But little progress has been made toward that goal. Since 1995, the gulf dead zone has averaged 15,323 square kilometers, not unlike this year’s prediction of the size of Connecticut. Nutrient-rich runoff from Midwest agriculture ends up in the Mississippi River and eventually makes its way to the gulf. The amount of nitrogen entering the Gulf of Mexico increased, mainly due to agricultural runoff, by about 300% between the 1960s and 1980s, and has changed little since then. </p>
<p>While the size of the gulf dead zone varies from year to year, mostly in response to changing weather patterns in the Corn Belt, the bottom line is that we will never reach the action plan goal of 5,000 square kilometers until more serious actions are taken to reduce the loss of Midwest nitrogen and phosphorus from agricultural lands, regardless of the weather.</p>
<p><strong>Chesapeake Bay</strong> - Similar to the Gulf of Mexico, the Chesapeake Bay dead zone forecast of 5.7 cubic kilometers (1.37 cubic miles or 2.3 million Olympic-size swimming pools) is slightly lower than its long-term average. Also similar to the gulf, there is very significant year-to-year variability in inputs and thus, hypoxia. But, unlike the gulf, there appears to be some progress being made toward <a href="http://www.chesapeakebay.net/indicators/indicator/reducing_nitrogen_pollution">nutrient input reductions</a>. </p>
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<a href="https://images.theconversation.com/files/86166/original/image-20150623-19368-1kp6zn5.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/86166/original/image-20150623-19368-1kp6zn5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/86166/original/image-20150623-19368-1kp6zn5.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=298&fit=crop&dpr=1 600w, https://images.theconversation.com/files/86166/original/image-20150623-19368-1kp6zn5.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=298&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/86166/original/image-20150623-19368-1kp6zn5.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=298&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/86166/original/image-20150623-19368-1kp6zn5.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=374&fit=crop&dpr=1 754w, https://images.theconversation.com/files/86166/original/image-20150623-19368-1kp6zn5.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=374&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/86166/original/image-20150623-19368-1kp6zn5.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=374&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Chesapeake Bay nitrogen loads.</span>
<span class="attribution"><span class="source">Donald Scavia</span></span>
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<p>Why? Under an <a href="http://www.epa.gov/reg3wapd/pdf/pdf_chesbay/BayTMDLFactSheet8_26_13.pdf">Environmental Protection Agency- (EPA) enforced regional compact</a>, six states and the District of Columbia have agreed to reduce the nitrogen load 25% by 2025. Notice the word “enforced.” Having in place a two-year milestone check in 2017 under the agreement’s Total Maximum Daily Load (TMDL) Watershed Implementation Plan should make a difference. Those metrics will be graded by the EPA, and if they are missed, warnings will be issued to members of the regional compact, and the consequences could include additional regulatory measures. The EPA recently determined that the region is likely to <a href="http://www.baltimoresun.com/news/opinion/editorial/bs-ed-pennsylvania-20150615-story.html">miss that goal by half</a>. So, real accomplishments will depend on the resolve of the EPA and the administration in power to be tough in 2017.</p>
<p><strong>Lake Erie</strong> - This year’s Lake Erie toxic algae forecast is for a bloom larger than the one in 2014 that <a href="http://www.jsonline.com/news/wisconsin/toxic-algae-cocktail-brews-in-lake-erie-b99344890z1-274542731.html">shut down the water supply</a> to a half-million people in Toledo, and approaching the record-setting massive <a href="http://graham.umich.edu/scavia/wp-content/uploads/2013/04/PNAS.pdf">2011 bloom</a>. It’s worth noting that only a week or two before the formal forecast, NOAA was anticipating a <a href="http://www2.nccos.noaa.gov/coast/lakeerie/bulletin/projection_2015-05.pdf">relatively mild bloom</a>, and the changed forecast was the result of one spring storm. Because these blooms are driven by diffuse phosphorus sources from the agriculturally dominated Maumee River watershed, this update is not surprising, and is a reminder of how much this issue is driven by these <a href="http://nca2014.globalchange.gov/highlights/regions/midwest">climate-induced increased storms</a>. </p>
<p>In addition, unlike the dead zones, these blooms are highly dynamic in both time and space. In fact, while the 2014 bloom was much smaller than the massive 2011 bloom, it formed near Toledo’s water supply, and local winds mixed the bloom into the city’s deep-water intakes. So bloom predictions, regardless of size, do not necessarily correlate with risk. Until the phosphorus inputs are reduced significantly and consistently so that only the mildest blooms occur, the people, ecosystem and economy of this region are being threatened. We cannot cross our fingers and hope that seasonal fluctuations in weather will keep us safe.</p>
<h2><strong>Using ecological models for scenario analysis</strong></h2>
<p>We also participate in these annual forecasts because these same models are used to help guide decisions on long-term nutrient input targets needed to reduce <a href="http://water.epa.gov/type/watersheds/named/msbasin/upload/2008_1_31_msbasin_sab_report_2007.pdf">dead zones</a> and <a href="http://graham.umich.edu/scavia/wp-content/uploads/2015/06/FINAL-Objectives-TT-report-en-150624-3.pdf">toxic blooms</a> to acceptable levels.</p>
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<a href="https://images.theconversation.com/files/86167/original/image-20150623-19420-cuek1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/86167/original/image-20150623-19420-cuek1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/86167/original/image-20150623-19420-cuek1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=446&fit=crop&dpr=1 600w, https://images.theconversation.com/files/86167/original/image-20150623-19420-cuek1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=446&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/86167/original/image-20150623-19420-cuek1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=446&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/86167/original/image-20150623-19420-cuek1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=560&fit=crop&dpr=1 754w, https://images.theconversation.com/files/86167/original/image-20150623-19420-cuek1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=560&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/86167/original/image-20150623-19420-cuek1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=560&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Forecasting track record.</span>
<span class="attribution"><span class="source">Donald Scavia</span></span>
</figcaption>
</figure>
<p>We have been tracking the accuracy of some of these annual forecasts and find the models do a pretty good job in years without hurricanes or tropical storms that disrupt dead zones prior to taking measurements. This increases confidence in using these models for providing advice on needed nutrient load reductions. </p>
<p>In fact, some of these models have been used to guide policymakers who set nutrient input reductions, and most reach the surprisingly consistent recommendations of reducing inputs by 35%-45%. However, while some of these <a href="http://www.graham.umich.edu/scavia/wp-content/uploads/2009/11/estuaries_3_models.pdf">recommendations</a> have been in place for over a decade, little progress has been made. Forecasts, scenarios, recommendations and agreements are obviously not enough.</p>
<h2>So what to do?</h2>
<p>In a <a href="https://theconversation.com/industrial-corn-farming-is-ruining-our-health-and-polluting-our-watersheds-39721">recent posting</a>, I suggested that while more extensive application of existing and new agricultural best management practices (BMPs), such as streamside buffers and wetlands restoration, are important, they alone may not be sufficient in reducing nitrogen and phosphorus inputs to the Gulf of Mexico, the Chesapeake Bay, and Lake Erie. Even if BMPs were effective, the current voluntary, incentive-based regime is not working, as outlined in a <a href="http://www.choicesmagazine.org/choices-magazine/submitted-articles/the-limits-of-voluntary-conservation-programs">report</a> by Marc Ribaudo, senior economist for the USDA Economic Research Service.</p>
<p>The fact is, our watersheds are overwhelmed by industrial-scale row crop agriculture, much of it corn, and real progress will be made only by reducing the demand for corn. That requires modifying the American diet, urging changes in the agricultural supply chain and cutting the production of corn-based ethanol.</p>
<p>While changing diets and supply chains requires long-term cultural change, cutting use of corn in our cars could be done more quickly. </p>
<p>A simple although apparently politically dangerous move would be for Congress to prohibit the use of corn for ethanol production. This has been proposed many times in many places. So why does the federal government continue to insist on burning corn in our gas tanks – especially since it has been <a href="http://www.ewg.org/research/ethanols-broken-promise/epa-s-emissions-assessment">demonstrated</a> that ethanol produces more greenhouse gases than gasoline and it is not good for either <a href="http://www.ewg.org/agmag/2013/02/corn-ethanol-bad-farmers-consumers-and-environment">consumers</a> or the <a href="http://www.ucsusa.org/sites/default/files/legacy/assets/documents/clean_energy/ew3/corn-ethanol-and-water-quality.pdf">environment</a>? Perhaps the answer lies with presidential hopefuls running to Iowa every four years proclaiming love for corn and ethanol, and an ethanol industry building a stronger <a href="http://thehill.com/policy/energy-environment/234393-ethanol-industry-lobbies-up">roster of lobbyists</a>.</p>
<p>These are, of course, political considerations worked out in Washington, DC and state capitals. In the meantime, the dead zones and algae blooms we forecast every year show the ongoing damaging effects of excessive nutrient runoff.</p><img src="https://counter.theconversation.com/content/43747/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Donald Scavia receives funding from government agencies and foundations in support of his research.</span></em></p>The same conditions – ultimately tied to nutrient runoff – that created the damaging toxic blooms and dead zones in US waterways of recent years are forecast to return this year.Donald Scavia, Graham Family Professor of Sustainability, University of MichiganLicensed as Creative Commons – attribution, no derivatives.