Anomalous heat hits polar region
Air temperatures over vast areas of Antarctica's ice sheets have risen by an average of 10 degrees above normal in the past month, which has been called near-record heat.
While temperatures remain below freezing on the polar landmass, which is plunged into darkness at this time of year, the height of winter in the southern hemisphere has seen temperatures reportedly reach 28C above expected on some days, The Guardian reports.
The globe has seen 12 months of record warmth, with temperatures consistently 1.5C above pre-industrial levels, which was thought to be the limit to avoid the worst effects of climate change.
Michael Dukes, director of forecasting at MetDesk, said that while the individual daily high temperatures were unexpected, what was far more significant was the average increase over the month.
Climate scientists' models have long predicted that the most significant impacts of human-caused climate change will be in the polar regions, «and this is a great example of that,» he said.
“You can’t usually just look at the climate trend for one month, but it’s exactly what the models predict,” Dukes added. “In Antarctica, typically you get this kind of warming in the winter and if it continues into the summer months, it could cause the ice sheets to collapse.”
Last month was the first in 14 months without a temperature record being broken, but that came after an exceptionally warm July in 2023, which remained 0.3C warmer than any previous July.
Zeke Hausfather, a research scientist at Berkeley Earth, said the Antarctic heat wave “was certainly one of the main drivers of the sharp rise in global temperatures in recent weeks.”
“Antarctica as a whole has been warming along with the rest of the world for the last 50 years, and for that matter for the last 150 years, so any heat wave starts from that elevated baseline,” he said. “But it’s safe to say that most of the spikes over the last month have been caused by extreme heat.”
The heat wave is the second to hit the region in two years, with the last one in March 2022 causing temperatures to soar to 102.5 degrees Fahrenheit (39 degrees Celsius) and the collapse of a Rome-sized portion of the ice sheet.
The July rise in Antarctica followed a particularly strong El Niño, a climate phenomenon that causes warming around the world, and was likely also a lagged effect of that event, coupled with overall temperature increases caused by climate change, Dukes said.
Scientists said the immediate cause of the heatwave was a weakened polar vortex, a band of cold, low-pressure air that swirls in the stratosphere around each pole. Interference from atmospheric waves weakened the vortex and led to higher temperatures at high altitudes this year, Amy Butler, an atmospheric scientist with the National Oceanic and Atmospheric Administration, told The Washington Post.
Jamin Greenbaum, a geophysicist at the Scripps Institution of Oceanography at the University of California, San Diego, said he was “definitely concerned about what’s in store for the region in the coming years.”
“Most of my field expeditions have been to East Antarctica, where I’ve seen increasing melting over the years,” he said. “While I’m certainly alarmed to see these reports of a weakening polar vortex causing extreme heat there, I’m also not surprised given that this is, unfortunately, an expected outcome of climate change.”
Jonathan Overpeck, a climate scientist at the University of Michigan's School of Environment and Sustainability, told Channel X that the heat wave was «a clear sign that climate change is really starting to transform the planet.»
Edward Blanchard, an atmospheric scientist at the University of Washington, told The Washington Post that it was a near-record event. «It's likely that less sea ice and a warmer Southern Ocean around the Antarctic continent are contributing to warmer winter weather in Antarctica,» Blanchard said.
“From that perspective, it might be a little less ‘surprising’ to see extreme heat waves in Antarctica this year compared to a ‘normal’ year with average sea ice conditions.”
Jonathan Wille, a researcher studying climate science at ETH Zürich, a public research university in Zurich, Switzerland, said the heatwave was caused by a “southern stratospheric warming” event that had been ongoing for weeks in the region.
“They’re really rare over Antarctica, so it wasn’t entirely clear how that would affect surface conditions on the continent,” he said. “It was interesting to see how big the impact was.”
While he said “it seems like heat waves are becoming more and more common on the continent,” he said it was not yet clear how big a role the climate crisis played in causing this particular event.
“We’ll have to wait until attribution studies figure that out,” he said. “It’s a wait-and-see scenario.”
Свежие комментарии