A new report shows that coastal habitats have the capacity to sequester 50 times more carbon per year in the sediment below them than equivalent sized tropical forests - but because they do not receive the same policy attention as the forests they have effectively become the 'missing sinks'.
Coastal saltmarshes, mangroves and seagrass meadows have a staggering ability to remove carbon from the atmosphere and lock it into soil, a new paper by a Conservation International scientist claims – prompting calls for urgent action to protect these vulnerable habitats.
In the paper Carbon Sequestration by Coastal Marine Habitats: Important Missing Sinks, Conservation International’s Dr Emily Pidgeon, describes how these habitats can sequester up to 50 times more carbon in the sediment below them than equivalent areas of tropical forest.
Dr Pidgeon, Conservation International’s Marine Climate Change Director, said: “The key difference between these coastal habitats and forests is that mangroves, seagrasses and the plants in salt marshes are extremely efficient at burying carbon in the sediment below them where it can stay for centuries or even millenia.
"Tropical forests are not as effective at transferring carbon into the soil below them, instead storing most carbon in the living plants and litter. But coastal ecosystems keep sequestering large amounts of carbon throughout their life cycle. Equally, the majority of carbon stays locked away in the soil rather than the plant, so only a relatively small amount is released when the plant dies.”
The paper, released by IUCN in the report The Management of Natural Coastal Carbon Sinks makes a compelling case for the protection of these ecosystems – which occur in areas as diverse as Britain, Australia, the Caribbean, the Mediterranean, and North and South America – and which are being lost at an alarming rate to human activity.
The report was supported by the United Nations Environment Programme (UNEP), The World Commission on Protected Areas (WCPA), Natural England and the Lighthouse Foundation.
Dr Pidgeon said: “Not only do these ecosystems help us to remove carbon from the atmosphere, but they are also very important as an adaptation tool to help some of the world’s most vulnerable people to avoid the worst impacts of climate change. It is imperative that we take steps to protect them immediately.”
For example, mangroves are important in protecting coastal communities from extreme weather, and also provide a nursery for many species of fish, which provide greater food security for these populations.
Seagrasses prevent coastal erosion and provide habitat for many commercially important species of fish, protecting livelihoods and salt marshes provide a buffer that prevent sediment from damaging fisheries, and may play a role in protecting freshwater aquifers from salt-water intrusion.
Dr Pidgeon said: “The sheer size of the world’s forests makes them essential for carbon sequestration. However, the immense carbon sequestration capacity of these coastal habitats has been almost completely ignored and may also be a vital component in global efforts to mitigate climate change.”
Dr Helen Phillips, Chief Executive of Natural England, said: “The role of forests and peatlands in helping to prevent carbon entering the atmosphere is widely recognised, but it is crucial not to overlook our coastal habitats, which can have just as much impact in helping limit climate change.
"Many of these coastal habitats, like tidal salt marshes, are under significant threat from development and rising sea levels, and urgent action is needed to prevent further damage to their essential carbon storage role. Natural England welcomes this compelling and timely research from the IUCN, which provides vital information on how these coastal carbon sinks work and why it is so important to preserve them."
The report highlights the wide-ranging benefits that coastal habitats provide and also the increasing threats that they face. For example, the loss of two-thirds of seagrass meadows and 50 per cent of mangrove forests due to human activities has severely threatened their carbon storage capacity and is comparable to the annual decline in the Amazon forests.
Natural England’s Professor Dan Laffoley, lead author of the report and also Marine Vice-Chair of IUCN’s World Commission on Protected Areas, said: “Over the past two years we have worked with a range of leading scientists to document the carbon management potential of particular marine ecosystems and understand how they can be successfully managed. Until now, surprisingly little attention has been paid to the ocean and its habitats, despite the fact that they form a critical part of the carbon cycle and one of the largest sinks of carbon on the planet. We cannot afford to ignore their potential.”
Posted on Environment Times online on 24th November 2009.