Scientists have documented the capacity of coastal habitats to bury and lock away carbon into soils and sediments in a major new report from the International Union for Conservation of Nature(IUCN).
The report outlines how seagrass meadows, mangroves and salt marshes have a much greater capacity to trap carbon than land carbon sinks, potentially storing 50 times the amount of carbon that tropical forests do on a per hectare basis.
These new revelations have led the IUCN to believe that ocean ecosystems are essential to combating global warming, explains Dr Hilary Kennedy, lead contributor to the chapter on seagrass meadows.
While the role of forests and peatlands in carbon sequestration has been relatively well documented, surprisingly little has been made of the role that coastal habitats play in storing carbon. “Although seagrass meadows cover a relatively small portion of the ocean (approx 1%), they constitute an important carbon sink, responsible for about 15% of the total carbon storage,” said Hilary Kennedy from Bangor University's School of Ocean Sciences.
At the recent Copenhagen Climate Change Conference, Carl Gustaf Lundin, head of the IUCN's Global Marine Programme also drew attention to the capacity for coastal environments to lock away carbon for thousands of years.
He emphasised the importance of seagrass meadows saying that "seagrass meadows may well be more effective in sequestering carbon than forests," and emphasised that "Investments in protecting coastal ecosystems might be a very cost-effective way to sequester carbon".
Hilary Kennedy further explains: “In addition to the benefits of carbon sequestration, seagrass meadows also perform other functions in the ecosystem such as providing nursery grounds and food for coastal food webs, sediment stabililisation, wave attenuation and shoreline protection.
“The overall result is to make seagrass meadows a very valuable resource, thought to be valued at £600 billion each year. However, many of the coastal habitats, including seagrass meadows, are under significant threat from development and degraded water quality.
“A recent assessment has found that seagrass meadows have been disappearing at a rate of 110 square kilometres each year. To put this in perspective, the loss of two-thirds of seagrass meadows and 50 per cent of mangrove forests is comparable to the annual decline in the Amazon forests.
“Thus urgent action is needed to prevent further damage.”
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