A new study from the Alfred Wegener Institute and MARUM at the University of Bremen looks at what happens to carbon released from thawing Arctic permafrost. Researchers took sediment cores near Herschel Island in Canada and found that most of the organic carbon washed off the coast stays buried in seabed sediments rather than quickly returning to the atmosphere. Microorganisms in the sediment convert only about ten percent of that carbon into gases that can reach the air. The team also used carbon isotopes to trace what the microbes were eating. The results show they prefer fresh marine carbon, like recent algae remains, over the older carbon from permafrost. That preference could mean thawing permafrost contributes less to atmospheric greenhouse gases than previously feared, though the authors note some carbon may already break down before it reaches the seafloor. The findings help refine estimates of how Arctic carbon feedbacks may affect future climate change.
