Seagrass beats rainforests as carbon sink

Seagrass meadows growing on ocean floors may be perfect carbon dioxide sinks, capturing greenhouse gases from the atmosphere and storing them for hundreds of years. These habitats are disappearing rapidly. Scientists are working to help nature restore them and to better understand their potential role in avoiding runaway climate change

Tropical rainforests are the carbon sink most often cited as a natural way of capturing and storing carbon dioxide. But rainforests are only the fifth most efficient ecosystem in the carbon storage cycle, new research reveals. Growing seagrass on ocean floors comes in second place among the most efficient ways of reabsorbing carbon.

Disappearing meadows

Despite the carbon storage properties of seagrass, its meadows are shrinking rapidly around the world. Pollution, discharges of nitrogen from industrial agriculture and warming seas, a result of climate change, are taking their toll. The meadows are losing 7% of their known areas a year globally, says Holmer. The rate of loss is faster than for rainforests.

Early success in Horsens fjord

Denmark is one of the countries that has lost most seagrass relative to its size, says Holmer. A nation of islands, Denmark’s extensive maritime territory was at one time home to massive areas of eelgrass, but much has disappeared, not least the victim of intensive agriculture. A project to test if eelgrass can be restored in coastal areas is being conducted by the Danish Environmental Protection Agency with the University of Southern Denmark. The main aim is to improve the marine environment, but a spin-off win is to recreate eelgrass meadows with positive effects for the climate and CO2 reduction, says the agency’s Harley Bundgaard Madsen.

FORESIGHT Climate & Energy is the essential read from Denmark on the global transition to a decarbonised energy economy

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