About 15% of the Northern Hemisphere is covered by permafrost. Permafrost is soil and sediment that has remained frozen for long periods of time, in some cases as much as 700,000 years. It contains large amounts of dead biomass that has accumulated over millennia and hasn’t fully decomposed. Therefore, permafrost is an immense carbon sink.
The Arctic is warming four times faster than the rest of the planet and, as a result, thawing permafrost is becoming a carbon source. As warming continues, ice is melting, and vegetation is spreading. A new study, published in Nature Climate Change, looked at the state of the Arctic and boreal north from the period 1990 until 2020. The study found that although half of the Arctic region has been growing greener, only 12% of those green areas are actually taking up more carbon. For one thing, the growth of forests means that there is more fuel for wildfires which are increasingly common.
A study of lakes in West Greenland found that thousands of crystal blue lakes have turned brown during record heat spells. Runoff from melting permafrost made the lakes opaque killing off plankton that absorb carbon dioxide. Meanwhile, plankton that release carbon dioxide multiplied. So, these lakes went from being carbon sinks to being carbon sources.
As the northern latitudes warm, ice and permafrost are melting, vegetation is spreading, and the region is becoming a source of heat-trapping gas after having been a place where carbon has been locked away for thousands of years. According to the Nature Climate Change study, roughly 40% of the Arctic is now a source of carbon dioxide.
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Warmer, Greener Arctic Becoming a Source of Heat-Trapping Gas
Photo, posted October 14, 2024, courtesy of Christoph Strässler via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio
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