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Blue carbon ecosystems

Though blue carbon is an increasingly popular term in the era of climate change, it still is a novel term for many. In order to fight climate change, it is imperative to understand its meaning and impact. The term basically refers to carbon that is stored in marine ecosystems. The National Ocean Service defines blue carbon as simply the term for carbon captured by the world’s ocean and coastal ecosystems. These important ecosystems include wetlands, mangroves, tidal and salt marshes, seagrasses, microalgae and also fishes. These coastal vegetated ecosystems grow in depositional soils in the coastal areas increasing carbon deposits on the coastline.

Why are Marine Ecosystems important?

Rising temperatures have not spared even seas and oceans, threatening life beneath the water and along the coastlines. The increasing CO2 in the atmosphere is also leading to ocean acidification. We all know that these aquatic ecosystems are for the survival of marine species. They provide habitat and food security to marine life. But they are more important than you think them to be.

Did you know that these ecosystems have more capacity to store carbon than terrestrial forests? Yes, they are around three times more capable of catching carbon and can thus be used as an essential nature-based solution to reduce the harsh effects of climate change. Even fishes have the capacity to store carbon. It is a crucial carbon sequestration medium that can sequester carbon in their biomass at a much higher rate per unit area. Most of this carbon is stored in the soils deep below the ground where it can exist for thousands of years.

According to the IPCC report 2019, the soils of marine angiosperm habitats can store carbon up to 1,000 tC ha−1. It is also estimated that the annual carbon sequestration rate for mangroves and tidal marshes lies between 6 to 8 Mg CO2e/ha (tons of CO2 equivalent per hectare. The report also says that it can help to mitigate 2% of total CO2 emissions.

These marine ecosystems provide multiple benefits apart from acting as a carbon sink. They help minimise the presence of carbon around water by capturing a lot of carbon in them. They act as protection walls against storms. They are also said to improve the quality of water. It is thus a pressing need to take every effort to stop its degradation and conserve these blue carbon habitats.

The harsh realities

Proliferation in coastal urbanisation, aquaculture, water pollution, fisheries and sedimentation have destroyed vegetated coastal habitats around the globe. Between the period of 2000 and 2016, 62% of mangroves and 90% of salt marshes were destroyed. They face the highest rates of loss. When ancient blue carbon stores like rhodolith/maerl beds found in seafloor sediments are damaged by bottom-trawled fishing gear, almost 1 gigaton of CO2 is released, equivalent to the annual emissions of the entire aviation industry. Bottom trawling kills organisms that are responsible for carbon cycling.

Preserving these ecosystems can be a boon for the world, whereas their degradation is a bane. When these blue ecosystems are destroyed, a lot of carbon and methane stored in them burst into the atmosphere, drastically increasing the atmospheric GHG levels. Thus it is important to preserve blue ecosystems to tackle climate change.

Importance of wetlands

Studies reveal that 20-30% of the world’s carbon is stored in wetlands. In spite of their relatively small surface, they hold a large amount of carbon. The dense vegetation in wetlands can help control the process of decomposition, which is otherwise said to generate a lot of GHGs. They also offer natural protection against storms and flooding.

Protection of marine ecosystems

These highly productive ecosystems that spread out largely under the oceans and along the coastlines across hundreds of countries are extremely valuable for humankind. They can significantly impact the risks of climate change. Scientists are continuously researching on how these ecosystems can be leveraged to mitigate climate change. Because the goal of blue carbon should not only be set to draw out carbon from the atmosphere but it also needs to be repurposed. One should not forget the amount of CO2 it could release back into the air if they are destroyed. Preserving these ecosystems is definitely the first step but expanding their utility should be the next step.


Blue carbon ecosystems can play a vital role in climate change mitigation strategy. But just like urban development is causing environmental degradation, coastal development too is causing marine ecosystem degradation. These threatened ecosystems will soon disappear if they are degraded at current rates. Their degradation will turn them into significant sources of greenhouse gases.

These natural ecosystems have become a topic of discussion at the UNFCCC (United Nations Framework Convention on Climate Change). Also, many developing countries are trying to raise funds to support their programmes on the conservation of blue ecosystems through REDD+ (Reducing Emissions through Decreased Deforestation), NAMAs (National Appropriate Mitigation Actions) and CDMs (Clean Development Mechanisms). Countries should implement strict coastal management policies in addition to the existing ones. They should also plan to use these ecosystems as a favourable option to generate carbon offsets and place them in voluntary carbon markets as doing this can provide attractive financial incentives for their conservation.

You can learn more about blue carbon ecosystems through an accredited ESG Expert Certification from Directors’ Institute.

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