‘Blue carbon’ stored in vegetated coastal systems could be underestimated

Source: Science for Environment Policy

Vegetated coastal ecosystems, such as mangroves, marshes and seagrasses, are an important carbon sink and their destruction increases greenhouse gas (GHG) emissions. A new study estimates that 0.15-1.02 Pg (petagrams) of CO2 are being released annually from degradation of these valuable ecosystems, resulting in economic losses of US$6-42 billion (€4.68 to 32.81 billion) per year.

It is widely known that deforestation leads to increases in GHG emissions, as forests store large quantities of carbon. Vegetated coastal ecosystems’ ability to store carbon, known as ‘blue carbon’, is less well known. The study aimed to be the first to provide a comprehensive estimate of global GHG emissions due to the conversion of vegetated coastal ecosystems to other land uses.

The study used figures from previous research on: the total global area of vegetated coastal ecosystems (marshes, mangroves and seagrasses), the percentage of these ecosystems being lost per year and the carbon stocks in these habitats that is susceptible to loss. It focused only on the biomass (plant material) and the top metre of sediment as scientific understanding of carbon losses from deep sediment is not yet adequate enough.

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