Blue carbon refers to the carbon stored in coastal and marine ecosystems like mangroves, seagrasses, and salt marshes. These ecosystems capture and store large amounts of carbon dioxide from the atmosphere, playing a significant role in mitigating climate change. Marine sediments, in particular, hold the largest store of organic carbon on Earth and carbon so buried results in long-term storage. Research in this field aims to better understand the carbon sequestration capacity of these ecosystems, the factors influencing their health, and how to enhance their carbon storage potential.
This strategy features in the framework of Agenda 21 as formulated at UNCED (Rio de Janeiro, 1992), now coordinated by the UN Commission on Sustainable Development and implemented through national and local authorities.
Recognizing the important role that oceans and all seas play in attenuating potential climate change, Agenda 21 recommends that the Intergovernmental Oceanographic Commission of UNESCO (IOC/UNESCO) and other relevant competent United Nations bodies, with the support of countries having the resources and expertise, should carry out analysis, assessment and systematic observation of the role of oceans as a carbon sink.
The concept of blue carbon was coined early in the 21st Century, but it was only in 2023, as the UN Framework Convention on Climate Change (UNFCCC) met in Germany in preparation for the next climate summit in November, that blue carbon began emerging as a mainstream global option for carbon sequestration and accounting.
The first blue carbon initiatives included coastal wetlands like mangrove forests and salt marshes. They were incorporated into carbon accounting under the UNFCCC in 2013. But the coastal and deeper ocean also offer carbon sequestration opportunities.
Fiords in temperate areas are among the hottest of hotspots, burying the largest amount of organic carbon per area in the world. Fiords occupy less than 0.1% of Earth’s surface, but researchers estimate they account for 11% of global marine organic carbon burial.
Understanding the intricacies of blue carbon sequestration not only enhances our ability to combat climate change but also underscores the urgency of protecting fragile coastal ecosystems. Furthermore, by quantifying the economic and ecological value of blue carbon, we can mobilize resources, advocate for conservation efforts and forge policy and restoration efforts that can have a substantial impact on reducing greenhouse gas emissions and safeguarding the delicate equilibrium of our oceans and coastal regions.
While researching blue carbon may have its merits, it's essential to question its overall significance in the broader context of environmental priorities. Some argue that the focus on blue carbon might divert resources and attention from more pressing environmental issues, such as deforestation, fossil fuel emissions and habitat loss. Moreover, the impact of blue carbon sequestration on global carbon budgets is relatively small compared to terrestrial forests.