Blue carbon
Description
The term ‘blue carbon’ refers to carbon stored in wetland ecosystems. Blue carbon projects make use of this by regenerating such ecosystems to foster carbon removal. This can include planting mangrove plants in coastal areas or improving the management of existing ecosystems. Carbon is sequestered from the atmosphere through the growth of plants as they capture CO2 through photosynthesis. The CO2 is stored in the ecosystem. In wetland ecosystems, vast amounts of carbon are stored not just in the plants themselves but predominantly in the soil. This is because the wet conditions prevent the carbon from being degraded and being turned back into CO2. There are many types of wetland ecosystems that can act as carbon storages such as mangroves, seagrass meadows, salt marshes, macroalgae and freshwater peatlands.
Reversal
Carbon storage reversal can occur if the ecosystems are disturbed and are no longer protected, for example if mangrove ecosystems are removed to create space for coastal development or seafood farming. In addition to these dangers coastal ecosystems are vulnerable to sea level rise which could damage the ecosystems and cause the release of carbon back into the atmosphere.
Readiness and scale
The readiness of blue carbon to be used for carbon removal depends on the type of project. Regenerating coastal systems such as mangrove reforestation are already deployed in many areas worldwide. Other projects such as marine permaculture are still being developed and are not yet available at scale. There are not many estimations on the global sequestration potential of blue carbon but because of the wide range of approaches.
Co-benefits / limits
+ Well-planned and managed blue carbon projects can foster biodiversity in the ecosystem.
+ Water quality can be improved through the fostering of wetland ecosystems because they filter water.
+ Intact coastal ecosystems play an important role in protecting the coast from flooding and storms. Regenerating and protecting these ecosystems can therefore protect nature and human life in coastal areas.
+ Regenerating coastal ecosystems can help fish stocks recover. This can provide food and income for local communities as well as create possibilities for tourism.
– Plants and the wetland soil only capture excess CO2 while they are growing. Once a plant and an ecosystem has reached maturity, there is still an exchange of CO2 and oxygen between the trees and the atmosphere but it is balanced, so the ecosystem does not function as a carbon sink anymore. This process is known as saturation. This means any single plot of the wetland ecosystem is a time limited carbon removal project.
– The measurement of carbon removal in wetland ecosystems is difficult.
– Wetland ecosystems such as peatlands release non-CO2 greenhouse gases such as methane. These contribute to climate change.
Extra info
Wetland and especially coastal ecosystems are currently being degraded and destroyed at very fast rates, even faster than rainforests. In addition to regenerating degraded wetland ecosystems, existing ecosystems have to be protected.
Support now
Support projects that use other methods as well as blue carbon in the future and contribute to the removal of CO2 from the atmosphere.
