Ground temperatures across much of Antarctica’s ice sheets have soared an average of 10°C above normal over the past month, leading to what is being called a near-record heatwave.
Though temperatures are still below zero on the icy continent, which is in the depths of southern hemisphere winter and shrouded in darkness, some days have seen temperatures 28°C higher than expected.
Globally, the past year has been marked by record warmth, with temperatures consistently exceeding the 1.5°C rise above preindustrial levels that is considered crucial for avoiding the worst impacts of climate change.
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Michael Dukes, the director of forecasting at MetDesk, noted that while individual daily high temperatures were striking, the more significant issue was the average temperature increase over the month.
“Usually, you can’t just look at one month for a climate trend, but it is right in line with what models predict,” Dukes added. In Antarctica, generally, that kind of warming in the winter and continuing into the summer months can lead to the collapsing of the ice sheets.”
Scientists explained that the heatwave’s immediate cause was a weakened polar vortex—a ring of cold air and low pressure that circulates in the stratosphere around each pole.
Amy Butler, an atmospheric scientist at the National Oceanic and Atmospheric Administration, told the Washington Post that atmospheric waves disrupted the vortex, leading to higher temperatures at high altitudes this year.
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Jonathan Wille, a researcher studying climate science at ETH Zürich, a public research university in Zürich, Switzerland, said the heatwave was attributable to a weeks-long “southern stratospheric warming event” over the region.
“Those are really rare over Antarctica, so it wasn’t really quite clear how that would affect surface conditions on the continent,” he said. “It’s been interesting to see how widespread the effects have been.”
