In the midst of a record summer in much of the northern hemisphere, beset by devastating fires, floods and hurricanes, Antarctica was mired in a deep and deep frost. This is usually the case during the winter months of the southernmost continent, but 2021 was different.
The cold was exceptional, even for the coldest place on the planet.
The average temperature at the Amundsen-Scott South Pole station between April and September, freezing cold of minus-78 degrees (minus-61 degrees Celsius), was the coldest on record, dating back to 1957. It was 4 , 5 degrees cooler than the most recent 30 year average.
We first learned of this record through a tweet from Stefano Di Battista, who posted research on temperatures in Antarctica. The legitimacy of Di Battista’s information was confirmed by Richard Cullather, a researcher at NASA’s Global Modeling and Assimilation Office.
The average temperature in September was also the coldest on record at the South Pole, wrote David Bromwich, a polar researcher at Ohio State University, in an email.
Extreme cold over Antarctica has helped push sea ice levels surrounding the continent to their 5th highest level on record in August, according to the National Snow and Ice Data Center.
Extremely cold weather continues to take hold of the Antarctic Plateau. Maximiliano Herrera, a climatologist who monitors extreme weather events around the world, tweeted that the temperature at Russian station Vostok dropped to minus 110.9 degrees (minus 79.4 degrees Celsius) on Thursday, September 30, which was only one degree (0.6 Celsius) of global temperature. lowest temperature ever recorded in October.
Current temperatures are still far from the coldest on record on the continent. In 1983, Vostok dropped to minus-129 degrees (minus-89.6 degrees Celsius). The satellites have detected temperatures as low as minus-144 degrees (minus-98 Celsius).
Matthew Lazzara, an Antarctic meteorological expert and scientist at the University of Wisconsin, has been watching temperatures at the South Pole in awe in recent months from his Madison office. In an interview, he said it was around minus -100 degrees on numerous occasions. Over the years, he has visited Antarctica several times to support his research.
“At these temperatures, it’s difficult to fly planes,” he wrote in an email. “[B]Between -50 ° C and -58 ° C, you endanger the aircraft with the hydraulic system freezing or the fuel turning to jelly.
He once visited the South Pole in late October. “I was able to experience a weather of -50 ° C. . .with a wind chill beyond that. I was * thrilled * to carry my 75 pounds of extreme cold weather gear to stay warm, ”he joked.
Conditions over Antarctica contrast sharply with those in much of the rest of the planet, which recorded its fourth warmest June to August month on record, according to the National Oceanic and Atmospheric Administration. The northern hemisphere recorded its second hottest summer.
Scientists have attributed the intensity of the cold to a very strong polar vortex, or a ring of strong winds in the stratosphere, surrounding Antarctica.
The stratospheric polar vortex is a seasonal phenomenon. In the southern hemisphere, it forms in the fall, persists throughout the winter, and weakens before reversing in the spring.
The force of the vortex has links to weather conditions on the ground, said Krzysztof Wargan, a researcher at NASA’s Global Modeling and Assimilation Office. He said a strong vortex is associated with low surface temperatures.
Whether the vortex is strong or weak depends on a cycle known as Southern Annular Mode (SAM). Right now the mode is in its positive phase and the vortex is intense.
“Basically the winds in the polar stratosphere were stronger than normal, which is associated with the jet stream moving toward the pole,” Amy Butler, atmospheric scientist at NOAA wrote in a post. “This keeps the cold air locked in over much of Antarctica.”
Butler wrote that the strong polar vortex not only makes it very cold over Antarctica, but accelerates the processes that lead to the depletion of stratospheric ozone, which in turn can further strengthen the vortex. This year’s ozone hole over Antarctica is much larger than average at around 24 million square kilometers, a reflection of the strength of the vortex.
Although the stratospheric ozone layer has been on the mend since certain ozone-depleting chemicals were banned by the Montreal Protocol in the 1980s, Wargan said the year-to-year variations other are expected to influence the size of ozone holes in the decades to come.
Scientists have pointed out that the record cold at the South Pole neither refutes nor diminishes the severity of global warming. Antarctica is known for its wild weather and climate fluctuations which can run counter to global trends.
Ted Scambos, a senior researcher at the University of Colorado, wrote in an email that the Antarctic climate is extremely sensitive to high-altitude winds and Pacific Ocean conditions and subject to rapid changes. He pointed out that its sea ice, which was near an all-time high at the end of August, had reached “one of the lowest areas for this time of year that we have seen” at the end of August. end of September.
To assess what’s going on with Antarctica’s climate, one needs to look beyond a seasonal snapshot, the scientists said.
“A cold winter is interesting but doesn’t change the long-term trend, which is warming,” Eric Steig, professor of atmospheric sciences at the University of Washington wrote in an email.
Not only does Antarctica warm in the long term, its ice is melting rapidly, contributing to sea level rise:
At the moment, however, the Antarctic cold is beyond numbness.
The temperature at the South Pole at the time of this article’s publication on October 1 was minus -67 degrees with a wind chill of minus-101.