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Marine Ecosystems Capture Carbon Emissions Equal to Near 50% of Emissions of Global Transport; UN Agencies Propose Blue Carbon Fund for Their Support

Carbon cycle. Credit: Riccardo Pravettoni, UNEP/GRID-Arendal. Click to enlarge.

A “Blue Carbon” fund able to invest in the maintenance and rehabilitation of key marine ecosystems should be considered by governments to combat climate change, according to a new Rapid Response Report released by the United Nations Environment Program (UNEP), the Food and Agriculture Organization (FAO) and the Intergovernmental Oceanographic Commission of UNESCO.

The report estimates that carbon emissions equal to half the annual emissions of the global transport sector are being captured and stored by marine ecosystems such as mangroves, salt marshes and seagrasses.

Blue carbon sink. Credit: Riccardo Pravettoni, UNEP/GRID-Arendal. Click to enlarge.

A combination of reducing deforestation on land, allied to restoring the coverage and health of these marine ecosystems could deliver up to 25% of the emissions reductions needed to avoid dangerous climate change.

But the report warns that far from maintaining and enhancing these natural carbon sinks, humanity is damaging and degrading them at an accelerating rate.

It estimates that up to 7% of these blue carbon sinks are being lost annually—seven times the rate of loss of 50 years ago. If more action is not taken to sustain these vital ecosystems, most may be lost within two decades, according to the report, “Blue Carbon: the Role of Healthy Oceans in Binding Carbon”.

The new report comes less than 60 days before the UN climate change convention meeting in Copenhagen where governments will seek to agree on a comprehensive new agreement.

The links between deforestation and climate change are firmly on the political radar and there is optimism that REDD [Reduced Emissions from Deforestation and Forest Degradation] will form part of a new global climate partnership, but the role and the opportunity presented by other ecosystems are still overlooked.

If the world is to decisively deal with climate change, every source of emissions and every option for reducing these should be scientifically evaluated and brought to the international community’s attention—that should include all the colors of carbon including now blue carbon linked with the seas and oceans.

—Achim Steiner, UN Under-Secretary General and UNEP Executive Director

Key findings from the Rapid Assessment Report include:

  • Of all the biological carbon, or green carbon captured in the world, more than half (55%) is captured by marine-living organisms—not on land—hence the new term blue carbon.

  • Marine-living organisms range from plankton and bacteria to seagrasses, saltmarsh plants and mangrove forests.

  • The ocean’s vegetative habitats, in particular, mangroves, salt marshes and seagrasses, cover less than 1% of the seabed.

  • These form the planet’s blue carbon sinks and account for more than half of all carbon storage in ocean sediment and perhaps as much as more than 70%.

  • They represent only 0.05% of the plant biomass on land, but store a comparable amount of carbon per year, and thus rank among the most intense carbon sinks on the planet.

  • Blue carbon sinks and estuaries capture and store between 235-450 Teragrams (Tg C) or 870 to 1,650 million tons of CO2 every year—the equivalent of up to near half of the emissions from the entire global transport sector which is estimated annually at around 1,000 Tg C, or around 3,700 million tons of CO2, and rising.

  • Preventing the further loss and degradation of these ecosystems and catalyzing their recovery can contribute to offsetting 3-7% of current fossil fuel emissions (totaling 7,200 Tg C a year or around 27,000 million tons) of CO2 in two decades&mash;more than half of that projected for reducing rainforest deforestation.

  • The effect would be equivalent to at least 10% of the reductions needed to keep concentrations of CO2 in the atmosphere below 450 ppm needed to keep global warming below two degrees Celsius.

  • Combined with action under REDD, halting the degradation and restoring lost marine ecosystems might deliver up to 25% of emission reductions needed to keep global warming below two degrees Celsius.

  • Unlike carbon capture and storage on land, where the carbon may be locked away for decades or centuries, that stored in the oceans remains for millennia.

  • Currently, on average, between 2-7% of our blue carbon sinks are lost annually, a seven-fold increase compared to half a century ago.

  • In parts of southeast Asia losses of mangroves since the 1940s are as high as 90%.

  • Large-scale restoration of mangroves has been successfully achieved in Vietnam’s Mekong Delta and salt-marsh restoration in Europe and the United States.

  • Countries with extensive, shallow coastal areas that could consider enhancing marine carbon sinks include India; many countries in southeast Asia; those on the Black Sea; in West Africa, the Caribbean, the Mediterranean, eastern United States and Russia.

Wider Benefits. Coastal waters account for just 7% of the total area of the ocean. However, the productivity of ecosystems such as coral reefs and these blue carbon sinks mean that this small area forms the basis of the world’s primary fishing grounds, supplying an estimated 50% of the world’s fisheries.

They provide vital nutrition for close to three billion people, as well as 50% of animal protein and minerals to 400 million people of the least developed countries in the world.

The coastal zones, of which these blue carbon sinks are central for productivity, deliver a wide range of benefits to human society. These include filtering water, reducing effects of coastal pollution, nutrient loading, sedimentation, protecting the coast from erosion and buffering the effects of extreme weather events.

Coastal ecosystem services have been estimated to be worth over US$25,000 billion annually, ranking among the most economically valuable of all ecosystems.

Much of the degradation of these ecosystems not only comes from unsustainable natural resource use practices, but also from poor watershed management, poor coastal development practices and poor waste management.

The protection and restoration of coastal zones, through coordinated integrated management would also have significant and multiple benefits for health, labor productivity and food security of communities in these areas.




There was a project that used wave pumps to bring plankton nearer the surface so that they could absorb more CO2. This was controversial because of potential unintended consequences. I remember seeing that sea animals also came closer to the surface to feed on the increased activity there. This should be very carefully examines before any deployment.


interesting article. Large portions of mangroves are used to create unsustainable shimp farms in some S.Am countries. Crazy as heck. One reason I boycott shrimp.

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