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Seagrass is a huge carbon store, but will government value it?

Australia is surrounded by a thin green line of seagrass meadows potentially worth A$5.4 billion on international carbon markets, and which could contribute to Australia and other nations meeting carbon…

Australia’s seagrass could earn A$35 million in carbon credits each year, if we have a trading scheme. sandwichgirl/Flickr

Australia is surrounded by a thin green line of seagrass meadows potentially worth A$5.4 billion on international carbon markets, and which could contribute to Australia and other nations meeting carbon emissions targets. Whether that potential can be realised is very much dependent on the type of carbon management scheme our next government puts in place.

Most people are aware forests lock up carbon dioxide from the atmosphere. This is a part of our carbon accounting scheme and underpins tree-planting and forest conservation schemes, giving value to this “green carbon”. Until now, the carbon captured by marine plant systems, so-called “blue carbon”, has largely been ignored in carbon accounting.

But our new research from Edith Cowan University (published today in the journal PLOS ONE) shows that seagrass meadows, hidden beneath our oceans, lock away between four and ten times that of our forests. Pound-for-pound, they are big hitters when it comes to snatching carbon out of the atmosphere.

We conservatively estimate that Australia’s 92,500 sq km of seagrass meadows contain more than 155 million tonnes of carbon. At a carbon trading price of A$35 a tonne (predicted by the Federal Government for 2020) that indicates a multi-billion dollar asset that can be used for tradable carbon credits.

In addition to the carbon these meadows have already locked away, they add about another 1 million tonnes of carbon each year, with a potential value of $35 million.

So lets look at how we realise this potential value, and how the next government’s approach to carbon could affect this.

Under the past government’s policy, the price of carbon was fixed until 2014-15. After that the price would be determined by the market, in an emissions trading scheme. The estimate of A$5.4 billion is based on the past Government’s predicted carbon-trading price of A$35 a tonne in 2020.

Exactly how that would be realised remains unclear. However, mechanisms such as the UN’s Reducing Emissions from Deforestation and Forest Degradation program have been used internationally to realise the value of leaving forests intact so their stored carbon is preserved.

This sort of mechanism may create enormous flow-on benefits: jobs could be created in assessment of marine carbon resources, bringing these to markets or through the creation of new marine habitats through re-vegetation schemes.

Scientists and economists in the Mediterranean region are currently working together to develop tool kits that would allow blue carbon stores to be brought to the carbon market.

In contrast, the Direct Action Policy proposed by the current opposition, appears to severely limit the potential to realise the value of blue carbon.

Under a direct action scheme, there is no value associated with not leaving the carbon in the meadow, and no penalty for disturbing that meadow and releasing the carbon into the atmosphere.

Unfortunately, seagrass meadows are under serious threat from nutrient pollution and coastal development. Every square kilometre lost releases 1.6 tonnes of carbon back to the atmosphere.

One possible way that a Direct Action Policy could give value to blue carbon is by rewarding the creation of new vegetated marine habitat, in the way we pay for re-afforestation. Unfortunately, the biggest carbon stores are found in seagrasses which are notoriously difficult to transplant or revegetate.

There will need to be a massive investment if we hope to be able to do with marine plants what we have learned to do with forests over hundreds of years. In the short-term, conserving and valuing what we have might be the cleverer approach. If we lose the habitat it may well be a long-term loss, even if we are going to invest in transplanting.

Australia’s Coastal Carbon Biogeochemistry Cluster, a collaboration of research providers, is working to further improve our estimate of carbon stored in marine habitats and how these might change in future climate scenarios. Meanwhile, our European colleagues continue to investigate the ways in which blue carbon can be brought to the carbon market.

Hopefully, Australia will realise that we have a valuable blue carbon resource that is worth protecting and can be done so with economic benefit, if only we are open to creative carbon trading schemes.

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10 Comments sorted by

  1. Wade Macdonald


    Australia already benefits from this important natural resource. If you want to conserve it through real conservation initiatives like this recreational fishing funded one that enhances estuary health these seagrasses inhabit, then I support the motive.

    However, this looks like an attempt to turn seagrass into a bag of carbon lollies for private enterprise? This almost always ends up in access loss or activity bans on recreational use for the rest of us.

  2. Colin Creighton

    Chair, Climate adaptation, Marine Biodiversity and Fisheries

    Hi Paul - the work the cluster is doing on coastal ecosystems to help define further the substantial mitigation benefits of coastal ecosystems is much appreciated. After all per hectare they are the most productive of the worlds ecosystems, including carbon. FRDC last year completed a scoping study which gave Australia the ballpark figures - see FRDC website - Lawrence, Baker and Lovelock project report.
    Our strategy? - well FRDC recognises that international public policy takes a while to develop…

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  3. Doug Hutcheson


    Seagrass meadows support grazing animals, such as dugongs. The carbon captured by seagrass is recycled through the food chain. How would we go about ensuring the carbon is sequestered? If it is not sequestered over the long term, surely it cannot contribute much to the global warming equations?

  4. Colin Creighton

    Chair, Climate adaptation, Marine Biodiversity and Fisheries

    Doug - yep there are consumers of all plants - whether they are terrestrial or nearshore marine.....but the bulk stays in the marine case within the sediments.....and from there think in medium term peat bogs or in longer time frames coal resources. All that "black gold" we are digging out here in Qld comes from largely marine sources a very long time ago. All carbon sequestration really does is start putting some of that back. hope this clarifies

  5. Paul Lavery

    Professor of Marine Ecology at Edith Cowan University

    Wade’s concern is understandable but, in this instance, there is good reason to believe that carbon sequestration and recreational use of seagrass meadows can happily co-exist. As Colin Creighton’s comments show, the fisheries management sector is well aware of the value of seagrass meadows and the push is towards sustaining these in order that fisheries can be maintained, as well as all the other ecosystem services that seagrasses provide. The carbon sequestration function of seagrasses is unlikely…

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  6. Michael Shand

    Software Tester

    Whats the bet that a company will be able to earn money by not further damaging this resource? essentially blackmail

  7. Colin Creighton

    Chair, Climate adaptation, Marine Biodiversity and Fisheries

    Not sure I would bet on the possibility just yet Michael. Despite the multiple benefits of seagrass such as fish and prawns [= food] we yet to have offset policies that work, sensible valuation of the enduring public benefits of estuaries and their seagrasses and any level of useful control over the catchment land uses, drainage of wetlands and so on that cause the problems. Nice idea though! I look forward to the day when all private sectors are competing to repair our estuary productivity. Unfortunately Aristotle in the 4th century BC is still relevant today - "That which is common to the greatest number has the least care bestowed upon it"...or as one of my fishing mates reckons - "Rivers - they won't fix them unless they catch on fire!"

    1. Wade Macdonald


      In reply to Colin Creighton

      Me too Colin 're : competing to repair our estuary productivity.

      It annoys me no end that rec fishing licence funding goes a lot toward's this...but the environmentalists want us rec fishers banned from these areas we are funding.