A record heat wave unfolding at what should be the coldest time in the coldest place on Earth has scientists worried about what it could mean for the future health of the Antarctic continent and the consequences it could inflict on millions of people. all around the world.
Temperatures since mid-July have risen as much as 50 degrees Fahrenheit above normal in parts of Antarctica and the unseasonably warm weather could continue through the first half of August.
The latest data shows that high temperatures in parts of East Antarctica – where the most abnormal conditions are ongoing – which are normally between minus 58 and minus 76 degrees Fahrenheit, are now closer to minus 13 to minus 22 degrees Fahrenheit.
That’s cold, but Bismarck, North Dakota, has reached minus 20 degrees at least once a year in almost every year since 1875. The typical winter cold in Antarctica should be operating at a level incomprehensible to most people In the USA.
The heat of summer in the depths of winter – even though much of the continent is still below freezing – is an alarming development for a place more capable than any other of generating catastrophic sea level rise as fossil fuel pollution continues to raise global temperatures.
Most of the planet’s ice is stored here, and if it all melts, would increase global average sea level by more than 45 meters. Even smaller icy features, like the so-called Doomsday Glacierit could raise sea levels by 3 meters if it melted – catastrophic amounts for the world’s coastal communities.
It’s possible that more heat waves like this one will occur in future winters, which could leave the icy continent less fortified for the hottest season — summer — and more vulnerable to melting during subsequent heat waves, said David Mikolajczyk, a research meteorologist. of the Antarctic Meteorological Survey. and the University of Wisconsin-Madison Data Center.
Increased Antarctic melt could also potentially alter global ocean circulations, Mikolajczyk told CNN. These circulations play an outsized role in making the planet’s climate habitable.
“I’m sure more (impacts) will emerge over time as we understand (this heat wave) better, but at the moment, it’s just a case of wonder what we’re seeing,” Thomas Bracegirdle, deputy scientific lead at said the British Antarctic Survey’s Atmosphere, Ice and Climate team.
Bracegirdle told CNN that the temperatures at this event were record-breaking and were an important sign of what could be to come in the long term. Heat waves of this magnitude are expected to be quite rare in Antarctica and scientists are not yet sure whether they are occurring more frequently, but that may be changing.
“All we can say at this stage is that more extreme temperatures are what we expect (in Antarctica) under a changing climate, but for this particular event we will have to study further,” Bracegirdle said.
It also contributed significantly to the new hottest day on record at the end of June, according to an analysis by the European Union’s Copernicus Climate Change Service.
This is the second significant heat wave that Antarctica has experienced in the last two years. During the previous one, in March 2022, temperatures in some locations reached up to 70 degrees above normalthe most extreme temperature changes ever recorded in this part of the planet.
This unprecedented heat wave was worsened by climate change, according to a study 2023 Study published in Geophysical Research Letters. Climate change contributed 3.6 degrees of warming to the heat wave and could worsen similar heat waves by 9 to 10.8 degrees Fahrenheit by 2100, the study found.
While the current heat wave hasn’t seen temperature changes reach the level of 2022, it has been much more expansive and long-lasting, according to Ted Scambos, a glaciologist at the University of Colorado in Boulder.
And the crucial differences between the two come down to what’s happening in the atmosphere.
‘A very unusual event’
The set of atmospheric conditions largely responsible for the ongoing heat wave – a disruption of the south polar vortex – is only expected to occur once every two decades on average, according to Bracegirdle.
“This is a very unusual event from that perspective,” Bracegirdle added.
Like the Northern Hemisphere, the Southern Hemisphere has a polar vortex – strong winds that circulate high in the atmosphere and trap cold air there.
But when the south polar vortex is disturbed, it releases trapped cold air over Antarctica and sends gusts further north. This also leaves the door open for air to descend from the upper atmosphere, warming along the way.
The south polar vortex is disturbed much less frequently than its northern counterpart, which explains why such heat waves are much less frequent, according to Amy Butler, a research physicist at NOAA’s Chemical Sciences Laboratory.
This polar vortex disturbance began in the second half of July and could continue through the first half of August, perhaps reaching peak intensity in about a week, Butler told CNN. This will keep surface temperatures high.
At the same time, multiple waves of warm air from the southwestern Indian Ocean pushed up East Antarctica – which comprises about two-thirds of the entire continent. Each wave of warm air has been followed by another so closely that warming has been almost continuous in recent weeks, according to Scambos.
East Antarctica — home to the South Pole — is home to the coldest conditions on Earth and is typically protected from this type of extreme heat, according to Mikolajczyk. But that was not the case at this event or in 2022.
It is part of a larger trend with already measured consequences.
The South Pole warmed more than three times the global average rate from 1989 to 2018, a 2020 study published in the journal Nature Climate Change found.
West Antarctica and its Thwaites “Doomsday” Glacier have been an important focus of scientific research in recent years due to the catastrophic impact their collapse would have on sea level rise. But other research in recent years has shown that melting in East Antarcticawhere this heat wave is happening, it is becoming equally worrying.
Recent heat has posed a significant problem for the continent’s crucial ice sheet. Antarctica lost an impressive 280% more ice mass in the 2000s and 2010s than it lost in the 1980s and 1990s, according to a 2019 study published in the Proceedings of the National Academy of Sciences.
“In recent years, I would say the feeling has been that the Arctic is the place where all the rapid changes are happening and (the changes) are happening very slowly in the Antarctic,” Mikolajczyk reflected. “But this is just another event that shows that (change) can happen quickly in Antarctica too.”
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