UNPRECEDENTED Arctic blazes last year appear to have smouldered through winter below ground as "zombie fires" only to reignite this month. Intense blazes across the frozen north in 2019 released record amounts of carbon - on a par with the annual emissions of Belgium - exacerbating the global warming that made the conditions for the fires possible in the first place. Now, as temperatures rise in the region and snow recedes, fires are erupting in Siberia again. Satellite analysis of last year's burn sites and the fires erupting this month suggest many may be zombie fires. "The satellite images are astonishing, particularly the snowmelt immediately followed by the fires appearing," says Thomas Smith at the London School of Economics. In an analysis for New Scientist based on imagery from the European Space Agency's Sentinel-2 satellites, Smith identified 2019 burn scars and 2020 hotspots. He found overlap of fires from last July and fires that appeared immediately after snowmelt this year. This includes known peatlands in tundra north of the boreal forest, where peat below ground could smoulder through winter. "I think there is some strong evidence for zombie fires," he says.
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