As the northern latitudes warm, ice is melting and vegetation is growing more abundant. But instead of absorbing more carbon, the region is becoming a source of heat-trapping gas, a new study shows.
The thaw of tundra is unleashing carbon, while the growth of forests means there is more vegetation available to burn in wildfires, according to the research, published in Nature Climate Change, which draws on data from across the Arctic and the boreal from 1990 to 2020. It found that roughly half of the region is growing greener, but only 12 percent of those greener areas are actually taking up more carbon.
While the far north has locked away carbon for thousands of years, with warming, roughly 40 percent of the region is now a source of carbon dioxide, the study found.
A separate study of lakes in West Greenland shows how changes are unfolding on a smaller scale. In the fall of 2022, some 7,500 crystal blue lakes turned brown amid a record hot spell. Instead of snow, rain came down, melting tundra. Runoff from the tundra made the lakes opaque.
Deprived of sunlight, plankton that absorb carbon dioxide died off. At the same time, plankton that release carbon dioxide multiplied. In the space of a few months, thousands of lakes went from being carbon sinks to being carbon sources, according to the study, published in the Proceedings of the National Academy of Sciences.
Such a widespread transformation would typically take centuries, said lead author Jasmine Saros, of the University of Maine. “The magnitude of this and the rate of change were unprecedented,” she said. “It was such an overwhelming climate force that drove all the lakes to respond in the same way.”
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