Ancient Arctic carbon is pouring into the sea, but the seabed captures most of it
Thawing Arctic permafrost is releasing ancient carbon into the ocean, raising fears that microbes could turn it into greenhouse gases and accelerate climate change. But sediment cores collected near Canada’s Herschel Island reveal a more reassuring twist: most of this land-based carbon becomes buried in the seafloor, while only about 10 percent is converted into gases.
The Arctic's frozen ground stores vast amounts of organic carbon, which can be released into the ocean as permafrost thaws. Researchers from the Alfred Wegener Institute and MARUM have examined this process along the permafrost coast of Qikiqtaruk (Herschel Island) in Canada. By studying sediment cores, they found that a significant portion of carbon from land is preserved in the seafloor.
Marine microorganisms act as selective eaters, preferring fresh ocean carbon over older carbon from permafrost. Up to 0.02 gigatonnes of carbon enter the sea each year, with forecasts suggesting this could increase by 70 to 150 percent by 2100. However, the study reveals that most of this carbon remains trapped in the seabed rather than being released into the atmosphere as a greenhouse gas.
The researchers caution that further research is needed to understand if older carbon from permafrost contributes less to atmospheric greenhouse gas levels than previously thought.
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