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Climate Change
The oceans play a pivotal role in the regulation of climate
change through the absorption and storage of heat, the uptake
and sequestration of carbon dioxide from the atmosphere, the
attenuation of storm surges, and the prevention of coastal
erosion. Thus the oceans mitigate both the drivers and effects
of climate change (SDG13
Take urgent action to combat
climate change and its impacts
).
The oceans absorb the vast majority of the heat trapped
by atmospheric greenhouse gases (GHGs), that otherwise
would have already warmed the atmosphere and fuelled the
progression of climate change (GOC, 2014).
Coastal ecosystems such as salt marshes, seagrass beds,
and mangrove forests all contribute to the sequestration of
carbon in marine sediments (i.e. ‘blue carbon’). Not only do
these systems draw CO
2
out of the atmosphere, but they also
trap carbon in detritus and sediment. Annual average carbon
sequestration rates range from 4.4 ± 0.95 tonnes CO
2
-eq per
hectare per year (for seagrass beds) to 8.0 ± 8.5 tonnes CO
2
-eq
per hectare per year (for salt marshes) (Murray et al 2011).
22
22 Estimated by converting grams of carbon sequestered to tonnes of CO
2
-equivalent and using the
social cost of carbon (SCC) for the year 2015 as shown in table A1 from IAWG (2013).
0
500
1 000
1 500
2 000
2 500
tCO
2
eq/ha
Seagrasses
Salt Marsh
Estuarine Mangroves
Oceanic Mangroves
Tropical forest
0
500
1 000
1 500
2 000
2 500
tCO
2
eq/ha
Seagrasses
Salt Marsh
Estuarine Mangroves
Oceanic Mangroves
Tropical forest
Soil organic carbon
Living biomass
Source: Murray and
et al
,
Green Payments for Blue Carbon Economic Incentives for Protecting Threatened Coastal Habitats
, 2011
Blue Carbon
EUO © OCEANA Juan Cuetos