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  • Kendall Plein

Blue Carbon: How We Can Harness Our Coasts to Mitigate Climate Change

Inland reforestation projects are increasingly part of offset efforts to draw carbon out of the air, but new research shows how coastal ecosystems are more productive carbon sinks.

Credit: Pexels/Ray Bilcliff

Blue carbon refers to the carbon sequestered in coastal ecosystems, powerful carbon sinks that are even more effective than terrestrial forests. It has been understudied and often ignored, but scientists and policymakers are now turning their attention to the coastlines.

To mitigate climate change, excess carbon dioxide needs to be removed from the atmosphere. Forests are an example of natural carbon sinks where large amounts of carbon can be stored instead of in the atmosphere. In addition, research shows that coastal ecosystems, like mangroves, seagrass and tidal marshes are also very efficient at sequestering significant amounts of carbon.

Coastal ecosystems are smaller in area than terrestrial forests but can sequester up to ten times more carbon per acre, Popular Science reported. Seagrass sequesters 10% of the carbon in ocean sediments each year. Most of the carbon in these ecosystems is stored in the soil — in some cases, up to 90%.

The bad news is mangrove forests are disappearing at a rate of about 0.6% per year. Additionally, coastal ecosystems are susceptible to destruction as beachfront property drives development on the coasts. As these ecosystems are degraded and destroyed, they release up to 1.02 billion tons of carbon dioxide a year. Therefore protecting these habitats is imperative. As more people are familiar with blue carbon, conservation projects and carbon credit trading schemes have expanded to include it.

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Coastal ecosystems are valuable for reasons other than their ability to absorb carbon. Coastal ecosystems are habitats for thousands of species, protect coastlines against storms and floods, and prevent erosion. Seagrass and mangroves can filter sediments and pollutants, but they are one of the most threatened ecosystems.

In the U.S. alone, mangroves provide $1.6 billion in ecosystem services, like hosting fisheries, filtering pollutants and protecting land from storm surges. Millions of people use mangroves and other coastal ecosystems to support their livelihoods, with fishing and harvesting prevalent as fish spend at least part of their lives in a coastal ecosystem.

Conservation projects from nonprofits and local governments can protect habitats and increase blue carbon levels. Additionally, including mangroves into the worldwide carbon trading market can incentivize the protection and rebirth of coastal ecosystems. Some estimates state habitat restoration costs as low as 10 to 100 USD per ton of carbon. At the very least, protecting and restoring coastal habitats maintain ecosystem services while sequestering carbon.

Increasing the dialogue around blue carbon in policy and economics can increase the likelihood of protection. As more decision-makers find the value in blue carbon, we can increase carbon sequestration and protect vital marine habitats.


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