Amid a record hot summer in large parts of Northern Hemisphere, beset by devastating fires, floods and hurricanes, Antarctica was mired in a deep, deep freeze. That’s typically the case during the southernmost continent’s winter months, but 2021 was different.
The chill was exceptional, even for the coldest location on the planet.
1/1 Extraordinary coreless winter (April – September) at South Pole Station. The average as been -61.1 °C the coldest ever recoded. This value set -2.2 °C on the reference 1981-2010 and -2.5 °C on 1991-2020. Previous record -60.6 °C in 1976 pic.twitter.com/m8uWF5mt0c
— Stefano Di Battista (@pinturicchio_60) October 1, 2021
The average temperature at the Amundsen-Scott South Pole Station between April and September, a frigid minus-78 degrees (minus-61 Celsius), was the coldest on record, dating back to 1957. This was 4.5 degrees lower than the most recent 30-year average.
We first learned of this record through a tweet from Stefano Di Battista, who has published research on Antarctic temperatures. The legitimacy of Di Battista’s information was confirmed by Richard Cullather, a research scientist at NASA’s Global Modeling and Assimilation Office.
From the article above,
‘The Amundsen–Scott South Pole Station experienced the coldest average temperature for April to September in 2021 on record. This chart displays the average temperature since 1957 in degrees Celsius. (Richard Cullather/British Antarctic Survey)’ pic.twitter.com/p4xWT3FHJx
— Scott Duncan (@ScottDuncanWX) October 2, 2021
The temperature averaged over September was also the coldest on record at South Pole, wrote David Bromwich, a polar researcher at Ohio State University, in an email.
The extreme cold over Antarctica helped push sea ice levels surrounding the continent to their fifth-highest level on record in August, according to the National Snow and Ice Data Center.
Extraordinarily cold weather continues to grip the Antarctic Plateau. Maximiliano Herrera, a climatologist who monitors world weather extremes, tweeted that temperature at Russia’s Vostok Station sunk to minus-110.9 degrees (minus-79.4 Celsius) on Thursday (Sept. 30), which was just one degree (0.6 Celsius) from the world’s lowest temperature on record during October.
Brutal cold in Antarctica, impressive even for the coldest place on Planet Earth.
The end of September came close to the world record for lowest temperature in October (-80°C).
The all-time cold record is −89.2 °C (−128.6 °F) from Vostok Station on 21 July 1983. pic.twitter.com/i2Mo1xjoEG
— Scott Duncan (@ScottDuncanWX) October 2, 2021
The current temperatures are still some distance from the coldest ever observed on the continent. In 1983, Vostok plummeted to minus-129 degrees (minus-89.6 Celsius). Satellites have detected temperatures as low as minus-144 degrees (minus-98 Celsius).
Matthew Lazzara, an expert on the meteorology of Antarctica and scientist at the University of Wisconsin, monitored the South Pole temperatures in recent months from his office in Madison with awe. In an interview, he said it was around minus-100 degrees on numerous occasions. Over the years, he’s traveled to Antarctica numerous times to support his research.
“At these temperatures, it is difficult to operate aircraft,” he wrote in an email. “Between -50°C and -58°C you put the aircraft at risk with the hydraulics freezing up or fuel turning into a jelly.”
Once he visited the South Pole in late October. “I got to experience -50°C weather … with a wind chill beyond that. I was *thrilled* to be wearing my 75 lbs of Extreme Cold Weather gear to stay warm,” he joked.
Reason for this cold anomaly
The conditions over Antarctica are in stark contrast to much of the rest of the planet which notched its fourth hottest June through August on record, according to the National Oceanic and Atmospheric Administration. The Northern Hemisphere registered its second hottest summer.
Scientists credited a very strong polar vortex, or a ring of strong winds in the stratosphere, surrounding Antarctica for the intensity of the cold.
The stratospheric polar vortex is a seasonal phenomenon. In the Southern Hemisphere, it forms in the fall, persists through the winter and weakens before reversing course in spring.
The strength of the vortex has connections to weather at the ground, said Krzysztof Wargan, a research scientist with 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 have been stronger than normal, which is associated with shifting the jet stream toward the pole,” wrote Amy Butler, an atmospheric scientist at NOAA in a message. “This keeps the cold air locked up over much of Antarctica.”
Butler wrote the strong polar vortex not only makes it very cold over Antarctica, but accelerates processes that lead to stratospheric ozone depletion, which in turn can strengthen the vortex even more. This year’s ozone hole over Antarctic is much bigger than average at around 24 million square kilometers, a reflection of the vortex’s strength.
Although the stratospheric ozone layer is on the mend since some ozone-depleting chemicals were banned by the Montreal Protocol in the 1980s, Wargan said year-to-year variations are expected to influence the size of the ozone holes in the coming decades.
What about solar activity?
It looks like September 2021 was the most active month for solar activity in terms of mean sunspot numbers since February 2016 as we continue to ascend out of the solar minimum of SC24/25.
Looks like September 2021 was the most active month for solar activity in terms of mean sunspot numbers since February 2016 as we continue to ascend out of the solar minimum of SC24/25. pic.twitter.com/InoSkMGshc
— Sryan Bruen (@SryanBruen) October 2, 2021
Scientists always omit speaking about that as a possible source of global cooling!
But of course won’t stop talking about the seriousness of global warming, arguing that Antarctica is notorious for its wild swings in weather and climate which can run counter to global trends.
Meanwhile, we have just observed the hottest (or joint hottest) October days in recorded history for 4 countries.
We have just observed the hottest (or joint hottest) October days in recorded history for 4 countries.
?? Iran 46.0°C (new record)
?? Morocco 43.5°C (new record)
?? China 38.9°C (tied record)
?? South Korea 32.3°C (new record) pic.twitter.com/DxErpjgkOp
— Scott Duncan (@ScottDuncanWX) October 3, 2021
At the moment, though, the Antarctic cold is beyond numbing. The temperature at the South Pole at the time of publication of this article on Oct. 2 was minus-77 degrees. [Seattle Times]
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