Sections

Services

Information

UK United Kingdom

How wetlands can help us adapt to rising seas

Instead of costly levees and seawalls, coastal ecosystems could offer an alternative way to protect Australia’s coastal communities from rising seas, saving money and storing carbon along the way. Sea…

Coasts are at risk from rising seas, but that risk could be alleviated by coastal ecosystems such as mangroves. Sheep"R"Us/Flickr, CC BY-NC-ND

Instead of costly levees and seawalls, coastal ecosystems could offer an alternative way to protect Australia’s coastal communities from rising seas, saving money and storing carbon along the way.

Sea levels around Australia are likely to rise 40 cm and up to 60 cm by 2100, driven by rising temperatures and melting ice-caps. The latest Intergovernmental Panel on Climate Change report on climate impacts and vulnerability shows more people will be at risk of flooding as a result of sea level rise. The report also focuses heavily on adaptation, and coasts show just how that might work.

Our coasts are already dynamic places, seeing regular erosion and inundation. In the past, poor recognition of this fact has left infrastructure and assets vulnerable — now increasingly so, thanks to sea level rise. If we’re to decrease the risk of future losses, we need to plan now to adapt. One way we could do so is by looking to nature.

Living coastal defences

Coastal ecosystems, such as wetlands, can increase the resilience of shorelines to erosion and inundation. This is starting to be recognised by coastal engineers, particularly in the US and Europe. Known as “living shorelines”, coastal wetlands are being constructed as an alternative to traditional engineering structures such as seawalls.

This “eco-engineering” is also starting to be recognised as a way for Australia to adapt to one of the 21st century’s major challenges.

Constructing wetlands, or helping existing wetlands retreat and accommodate rising seas, could offer significant economic gains while protecting coasts. Living shorelines could save between 30-80% of the cost of constructing hard structures such as seawalls, and once established they have minimal ongoing maintenance costs.

In Australia, tidal floodgates on the Hunter River in NSW once held back tidal waters. Now the river is a beacon for coastal adaptation. Tidal flow is being restored to the coastal floodplain, converting marginal farmland and freshwater wetlands into mangrove and saltmarsh.

The new habitat will provide more nurseries for fish. Costings from mangrove habitats show that this could generate A$14,000 per hectare each year to commercial fisheries.

Coastal wetlands are also amongst the most efficient ecosystems at sequestering carbon from the atmosphere. Expanding our wetlands could go some way to Australia’s climate mitigation efforts. In a paper recently published in the journal Estuaries and Coasts, we estimated how much carbon could be stored on the Lower Hunter.

We found 280,000 tonnes of carbon could be stored by 2100 if floodgates are opened and wetlands are helped to retreat and accommodate rising seas. Based on a carbon price derived from the European Union’s emissions trading system (fluctuating between A$7.30 and A$46.40 per tonne), we calculated the carbon sequestered in these wetlands could be worth between A$2 million and A$13 million in a carbon sensitive economy.

Irrespective of a mandated emissions trading scheme, this sequestered carbon may potentially provide financial incentives for coastal wetland restoration and conservation, through programs such as REDD+ and voluntary carbon markets like Verified Carbon Standard.

Working with nature

There are other ways to work with nature on our coasts, and these may have benefits beyond adapting to sea level rise. All of the following examples are already in practice in parts of coastal Australia.

Adding sand to beaches to protect them from sea level rise and storms can also minimise loss of amenity, unlike traditional seawalls.

Sand bypass projects build upon traditional beach nourishment by shifting sand from channels used for navigation to beaches where it is needed. Dredge spoil is being used in the same way on estuarine shorelines.

Oyster beds are being established as bulkheads to reduce wave action. And dunes are being rehabilitated to provide a buffer, as well as habitat for wildlife such as turtles and penguins.

Working with nature also applies to planning. Development should be confined to those areas that are already resilient to sea level rise, only approving developments in areas resistant to erosion and above the height impacted by rising seas and storm surges.

Planning also extends to coastal ecosystems. Sensible planning would acknowledge that coastal ecosystems produce many benefits, including protection from sea level rise. Local, state and federal governments need to start discussing how to accommodate the migration of coastal ecosystems as a result of sea level rise. Boundaries of coastal ecosystems will change. Planners need the vision to recognise this, and resist pressure from those who won’t.

Our coastal future will be different to our coasts as we know them. We now know some of the ways we can adapt to this future.

Articles also by These Authors

Sign in to Favourite

Join the conversation

73 Comments sorted by

  1. john byatt

    retired and cranky at RAN Veteran

    A solution to rising and acidifying oceans?

    Climate change mitigation
    The conservation and protection of ecosystems that act as carbon
    sinks are among the cheapest, safest and easiest solutions to reduce
    greenhouse gas emissions

    http://www.sciencedaily.com/releases/2013/05/130530095020.htm

    There is a danger in believing that land carbon sinks can solve the problem of atmospheric carbon emissions because this legitimises the ongoing use of fossil fuels," Professor Mackey said.
    ]
    Everything we do to improve resilience is worth it, but it is not a solution, the only solution is reducing greenhouse emissions

    report
    1. John Campbell

      farmer

      In reply to john byatt

      Yes there is a danger a bit like our PM who implies that the solution to CC is to plant a tree or two.

      I think you could see a bit of a tug of war here, depending on just how fast sea level rise occurs, between land developers anxious to get their hands on coastal real estate, and those who want to protect the environment. While sea level rise is reasonably slow and benign it is hard to see the latter winning.

      report
    2. john byatt

      retired and cranky at RAN Veteran

      In reply to John Campbell

      and even before 2100, SLR will impact storm surges and HATs

      report
    3. Jason England

      repairer

      In reply to Chris O'Neill

      So then you may be able to explain why it becomes less "acidic" regularly.

      report
    4. Jason England

      repairer

      In reply to Chris O'Neill

      So you're claiming pH levels don't fluctuate?

      Only become more "acidic", with our emissions?

      report
    5. john byatt

      retired and cranky at RAN Veteran

      In reply to Jason England

      Did you say that temperatures don't fluctuate only become more warm with our emissions ?

      report
    6. john byatt

      retired and cranky at RAN Veteran

      In reply to Chris O'Neill

      Please Chris hush hush or Watts will have a post up "Arctic gaining more ice, oceans becoming less acidic, i can see it coming.

      report
    7. john byatt

      retired and cranky at RAN Veteran

      In reply to Jason England

      Thanks for that, I had no idea except the clue in the graph, worth reading about wasn't it?

      report
  2. Colin Creighton

    Chair, Climate adaptation, Marine Biodiversity and Fisheries

    And if you want a blueprint for what we can do repairing EXISTING wetlands around Australia - see:
    http://frdc.com.au/research/Documents/2012-036-Business-Case.pdf.
    This provides a compilation of comparatively "easy to do" repair activities.Estimated total cost less than $350M...and all that investment repaid in increased seafood in less than 5 years.
    Should be the first investment in our Governments proposed Infrastructure Plan.

    report
    1. john byatt

      retired and cranky at RAN Veteran

      In reply to Colin Creighton

      Colin you do not seem to be in agreement with marine parks?
      https://theconversation.com/marine-reserves-help-fish-resist-climate-change-invaders-20960

      Hi Amanda - thanks for the article. I come though to a different conclusion than you. To me - the answer is all about repairing habitat and then making sure all impacts, fishing, dredging, water quality from catchments, estuary and nearshore habitat losses to development, seismic surveys and so on are managed with sustainability the key. Marine park reservations without repairing the cause of the impacts are a nonsense.

      reply appreciated

      report
    2. Colin Creighton

      Chair, Climate adaptation, Marine Biodiversity and Fisheries

      In reply to john byatt

      Hi John - you know if we were totally rational in our land use then parks, both terrestrial and marine "would just happen". We would value natural ecological processes and ecosystems.
      What I strongly object to is irrationally locking areas up where a line on a map is not the answer to the problem. For our fisheries and our marine systems the first priority is repair the nursery habitat of about 75% of the species we find in these areas.....that is the estuarine and nearshore habitats that we as humans have trashed with virtually no thought to food security let alone conservation values.

      report
    3. john byatt

      retired and cranky at RAN Veteran

      In reply to Colin Creighton

      Read that paper Colin, it is misinformation to the point of being fraudulent, it is claiming that the natural carbon cycle referenced for wetlands absorbs 80% of our FF emissions,
      The natural carbon cycle absorbs 45% of all human emissions with much going into the oceans and causing acidification.

      bottom line is that 45% of Australian emissions remain in the atmosphere and will do so for thousands of years

      report
    4. john byatt

      retired and cranky at RAN Veteran

      In reply to john byatt

      Apologies. nearly 60% of our emissions remain in atmosphere, so the sequestering claim of 80% just for wetlands is wrong

      report
    5. Ted O'Brien.

      Farmer.

      In reply to john byatt

      If you want to sort out sustainability, the first place to look is at the methods used to mine coal and CSG.

      Much of what is being done would never pass a morality test in any other industry.

      report
  3. Comment removed by moderator.

    1. Mike Hansen

      Mr.

      In reply to Jason England

      I see that the climate science denier Jason England has trolled this article with his "invincable ignorance".
      http://en.wikipedia.org/wiki/Invincible_ignorance_fallacy

      "SLR is not showing any increase and hasn't for decades" is fact free nonsense.

      Note that he **never** provides any evidence or scientific references to support his claims - if he did he would have to disclose which climate crank blog he reads.

      report
    2. Jason England

      repairer

      In reply to Mike Hansen

      '"SLR is not showing any increase and hasn't for decades" is fact free nonsense.'

      Is it Mike?

      If that's the case you can point me to some visible SLR.

      Where is it?

      It's not in Sydney Harbour where Fort Denison is just as it was a century and more ago.

      It's not in Moreton Bay where things haven't changed during white settlement.

      It's not in Holland where the dykes are still doing the same job they have done for centuries.

      It's not in England where the 2,000 year old remains of…

      Read more
    3. Jason England

      repairer

      In reply to john byatt

      John, you weren't paying attention.

      I said VISIBLE SLR.

      That doesn't include poorly referenced satellites being adjusted to tell a suitable narrative.

      Do you know of any visible examples of SLR that you can point to and say that's how high the sea has risen since such and such a time?

      Do you think if science had such an example they would not shout about it?

      The last of the visible SLR probably ran out about 6-8,000 years ago.

      report
    4. Chris O'Neill

      Retired Way Before 70

      In reply to Jason England

      "The last of the visible SLR probably ran out about 6-8,000 years ago."

      So someone saw that?

      Cool.

      By the way, where did they write about it?

      report
    5. john byatt

      retired and cranky at RAN Veteran

      In reply to Jason England

      doubt that you would notice 70mm in nearly 20 years even if you were in one of the higher rate areas, bangladesh is suffering from compaction subsidence and SLR,already.,rate about three times average, SLR increase and acceleration is directly linked to global warming and has been accelerating (Rahmstorf)

      what is the difference between visible slr and satellite measured SLR

      have a friend who lived on funafuti on the lagoon side and his house was one metre closer to high tide in less than a decade, during the HAT the sea water now comes up through the coral and sits on top of the ground, so that would be visible SLR , the coral there had been growing and keeping up with SLR but the pace has been too fast and it is losing the battle

      report
    6. Jason England

      repairer

      In reply to john byatt

      "what is the difference between visible slr and satellite measured SLR"

      John, visible SLR is what you can believe in and sat measured SLR is like Envisat.

      Envisat recorded virtually no SLR for years until it was correctly indoctrinated. Then lo and behold it fell into line with all the rest.

      But this is the real world. Sydney has had ~ two and a half inches of SLR over the last century:

      http://tidesandcurrents.noaa.gov/sltrends/sltrends_global_station.shtml?stnid=680-140

      Coral islands suffer from too many people and too much erosion. IE they don't work like they were meant to.

      It's a wonder such low lying islands have survived as long as they have with such huge populations.

      report
  4. Whyn Carnie

    Retired Engineer

    Here we go again. This proposal will open the floodgates to wetland lovers all over to beat their drums. There is no world shand anyway thortage of mangroves and the mud midges and mosquitoes that go with them. The premise that moving the high tide line landwards will somehow give us more seems flawed to me. I think that the equivalent low tide mark encroacment could simply negate things or make it better as there would be a net reduction in shorelines.
    Shifting clean sand back onto beaches is a good idea but just try that in Moreton Bay. Mud lovers would not stand for that.

    report
    1. John Campbell

      farmer

      In reply to Whyn Carnie

      The problem is Whyn that killing every mosquito, midge and everything else you find objectionable can have unintended side effects on those things you don't find objectionable.

      I'm not suggesting we allow the likes of malaria to flourish, but our first priority should be to find ways of living with things rather than killing everyone in sight.

      report
    2. john byatt

      retired and cranky at RAN Veteran

      In reply to Whyn Carnie

      just remembered that when he arrived he was looking at some old photos on the wall at the club and asked why they had moved the airport fence closer to the water, they had not of course it was visible sea level rise

      report
  5. john byatt

    retired and cranky at RAN Veteran

    The Great Sandy Strait is going to lose most of the tidal flats and will have nowhere to retreat to,

    report
    1. Rotha Jago

      concerned citizen

      In reply to john byatt

      Rising sea levels is a scary prospect. Rehab for wet lands is sensible. But, apart from Climate Change why are wetlands dying?
      Mangroves and Ti trees are all herbs. Why not suspect Herbicide?
      Ask your local Council how much herbicide they spread. Mine will not give an answer. Neither will they explain why areas once free of herbicide, now have to be regularly sprayed.
      They say it is cheaper but cannot justify that claim.
      Herbicide reduces drought resistance, decreases soil moisture,
      Increases soil degradation and erosion. Are we overlooking a cause of local problems because of our concern about the Big Picture?

      report
    2. In reply to john byatt

      Comment removed by moderator.

    3. In reply to john byatt

      Comment removed by moderator.

    4. John Campbell

      farmer

      In reply to Jason England

      I don't know that your comment really deserves a sensible answer, but you do know the AGW will and is changing weather patterns throughout the world don't you?

      report
    5. john byatt

      retired and cranky at RAN Veteran

      In reply to Jason England

      Two centuries or less will see the low tide above the current high tide

      report
    6. Whyn Carnie

      Retired Engineer

      In reply to john byatt

      John, any estimate when we will see this start to happen? I have been waiting since IPCC1 for a sign.

      I once thought I may not survive long enough to see any of the original dire predictions proven or disproven. The rising tide will have to occur pretty fast. I had hoped to be abler to moor my boat at my back fence but so far no measurable change. But I am only using obsevation.

      report
    7. Whyn Carnie

      Retired Engineer

      In reply to Whyn Carnie

      On that graph, not only my backyard but also the beach where I grew up should be under water. They're not, I am pleased to report.
      Which beach were the figures in the graph taken from? Shouldn't matter because it is all the same ocean.

      report
    8. Mike Hansen

      Mr.

      In reply to Whyn Carnie

      "Shouldn't matter because it is all the same ocean."

      Not true. Sea level rise is not evenly distributed. The oceans are not like bathtubs. There are gravitational effects, subsidence and isostatic rebound effects that need to be taken into account.

      These maps while not all that clear indicate the principle.
      http://www.cmar.csiro.au/sealevel/sl_proj_regional.html

      e.g. "In the Australian region, a common feature in many model projections is a higher than the global average sea-level rise off the south-east coast of Australia..."

      and more here
      http://www.cmar.csiro.au/sealevel/sl_drives_geol.html

      report
    9. john byatt

      retired and cranky at RAN Veteran

      In reply to Whyn Carnie

      " Shouldn't matter because it is all the same ocean."

      report
    10. Whyn Carnie

      Retired Engineer

      In reply to john byatt

      I still think it is the same ocean. John's graph implies this. The premise that somehow there has been or is soon to be an increase in the mass of the ocean over recent time implies that the level of that ocean, give or take waves, temperature, moon and all the variables that cause local height changes, will increase.
      I think I may have enough time left to witness the proposed change, not in models but in the real thing.

      report
    11. Chris O'Neill

      Retired Way Before 70

      In reply to Whyn Carnie

      "not only my backyard but also the beach where I grew up should be under water"

      So your backyard is lower than the beach? Wow.

      report
    12. john byatt

      retired and cranky at RAN Veteran

      In reply to Whyn Carnie

      mike is correct, the ocean is lumpy, it is not a mill pond and even pressure systems have a big effect, with sea water running across the roads in some brisbane streets due to a king tide and pressure system off the coast,

      report
    13. Chris O'Neill

      Retired Way Before 70

      In reply to Whyn Carnie

      "Two different States"

      Didn't you say it was the same ocean, or was that someone else?

      report
  6. john tons

    retired redundant

    Excellent idea. Here in South Australia much of the coastline consisted of mangrove swamp - only remnants are still there today. But there is a downside - mangroves are also excellent breeding grounds for mosquitos - the ones from the St Kilda mangroves are big enough to carry off a small child but that irritation aside the St Kilda mangroves are one of the few areas along our coast line that teems with life. Most of our beaches are dead sterile places but here there is life.

    report
    1. john byatt

      retired and cranky at RAN Veteran

      In reply to john tons

      Tidal wetlands are extremely sensitive to sea level rise. For
      example, too much flooding and mangroves will “drown”, On the great Sandy Strait the mangroves will have no where to go, the numerous mangrove islands will go under.

      report
    2. Jason England

      repairer

      In reply to john byatt

      John, you don't know much about SLR and mangroves do you?

      report
  7. Comment removed by moderator.

  8. Kate Newton

    logged in via email @ymail.com

    This all sounds good to me, but try convincing the waterfront owners on Lake Macquarie, for instance.

    report
  9. Bob Bingham

    Mr.

    It sounds plausible but giving up a big city like Shanghai, London or New York in return for a few seagull nests will not go down well with the residents. Its cheaper to not burn the fossil fuel in the first place, although that may no longer be an option. http://www.climateoutcome.kiwi.nz/sea-level.html

    report
  10. Fred Moore

    Builder

    I have been campaigning for Engineered Wetlands and Coastal Mangrove restorations since 2001 on the New York Times Environment Fora.

    There should have been some progress in this area globally but some odd problems have arisen.

    1. MOZZIES

    2. Hijack by construction companies increasing the cost of a 1 acre Engineered Wetland to abover $3million.

    3. Working in mud and silt IS an expensive business BUT Community Participation with sufficient foresight and dedication and with local Government…

    Read more
  11. Gary Luke
    Gary Luke is a Friend of The Conversation.

    thoroughly disgusted

    "Sea levels around Australia are likely to rise 40 cm and up to 60 cm by 2100"

    Nobody reading this today will be around to verify whether the figures are valid. Crunch some other numbers and ... anyone can throw numbers around. One person can say "no it won't" and another can say "it's gunna be much worse".
    Will someone please predict something tangible with an expiry date in the next two decades so everyone can know how reliable their predictions are.

    report
    1. john byatt

      retired and cranky at RAN Veteran

      In reply to Gary Luke

      Up to 98cm by 2100, my great grandaughter may get to see it, why do they need to be able to read this when the information will be on the IPCC reports in archive?

      check out different projections for each RCP

      report
    2. john byatt

      retired and cranky at RAN Veteran

      In reply to john byatt

      does it really say that australian sea level rise will be nearly 30cm below the average rise, citation?

      report
    3. Whyn Carnie

      Retired Engineer

      In reply to Gary Luke

      I've been watching for the last two decades and would have to question the predictions from 1990 on.
      As predictions did not eventuate there were various explanations put forward and the "models' were tweaked and/or the base data were revised.
      The underlying base claims morphed from the purist global warming through the bloody obvious, climate change, restricted greehnouse gas effects, but always linked inextricably to the trace bipolar gas carbon dioxide. Always as choreographed in the interminable…

      Read more
    4. Gary Luke
      Gary Luke is a Friend of The Conversation.

      thoroughly disgusted

      In reply to john byatt

      If the world average sea level is such-and-such, then some areas will be lower and some will be higher, and some might be even further outliers either low or high. If things like that really need an explanation then how does everyone manage to cope with the complex statistics that produced these predictions?

      report
    5. john byatt

      retired and cranky at RAN Veteran

      In reply to Gary Luke

      I am sure that they are much more capable of reading the data than me but the color coded SLR seems to only refer to RCP 4.5 on the link

      report
    6. Whyn Carnie

      Retired Engineer

      In reply to john byatt

      Whoa back. I must have been asleep on watch. Is this 30 cm below the average rise applicable to the 40 to 60 cm quote previously? Hope it is because then we are only looking forward to 10 to 30 cm POSSIBLE rise in Australia and I am comfortable with that.
      Not enough to get my boat up to the back gate.

      report
    7. john byatt

      retired and cranky at RAN Veteran

      In reply to Whyn Carnie

      No they did say 40 to 60 cm around australia so would not be applicable,

      under RCP 8.5 the 2100 average SLR is 98cm for 2100

      report
  12. John Perry

    Teacher

    Wasn't there a Conversation article a month or so ago where they showed how mangroves can slow down and take the force out of tsunamis? Awesome! Mangroves are fantastic.

    report
  13. Gary Luke
    Gary Luke is a Friend of The Conversation.

    thoroughly disgusted

    The Lands Department Building in Bridge St Sydney has a datum marker on the front wall with an indication of high tide level in Sydney Harbour. It was put there some time between 1887 ans 1894. Has anyone checked how much the current level has altered against this benchmark?

    report