Science: Growing Awareness of “Blue Carbon”

The Story:

“Blue carbon” is gaining currency as a useful name for an often-overlooked part of the discussion of climate change. There is a general understanding that forests (“green carbon”) are important. The trees live for centuries, and they sequester carbon. But what is often overlooked is that marine life can be more valuable for sequestration than forests. Blue carbon may matter more than green.


The blue portion of the carbon cycle can be divided into three stages.  First, plants — often tiny and transient plants such as algae, capture carbon from the atmosphere. Second, there is storage. The carbon in those plants finds its way into animals, herbivorous animals that eat marine vegetation and, in time, carnivores that eat them.  The final stage is blue carbon sequestration. The fish that embody the carbon die and their bodies sink into the soil at the bottom of the ocean. It is immobilized by corals. In this way, the “blue” system takes carbon out of the atmosphere for more than a century at a time. In other words, the sea floor is an effective carbon sink. 

Strange New Worlds

Scientists at Manchester Metropolitan University in England found that the Steart marshes, near Somerset, absorbed 19 tons of organic carbon a hectare every year. Climate scientists have only begun to fit this new understanding of blue carbon into the big picture on a planetary scale.

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