A look back at this week's extreme warmth in the Arctic and Antarctic, as atmospheric rivers pumped warm, moist air poleward.
We’ve had plenty of fine weather and warm sunshine here in the UK this March with temperatures several degrees above average. Even reaching 20C a few times, and although the UK record is much higher at 25.6C. This month in the Arctic and Antarctic, it has also been relatively warm. For the Antarctic, instead of being -40 to -50C it has been -20 to -10C. Both poles have seen ‘heatwaves’ with temperatures 30 to 40 degrees C above the norm.
Many articles have appeared around the record-breaking high temperatures but also the extent of the sea ice and its conditions after these warm air events. Scientific investigations and studies continue about Arctic Amplification; why there is stronger warming of the Arctic compared to the global mean warming, NASA saying 3 times faster.
These recent polar events have been notable. Polar scientists expressing utter surprise and concern of what they might herald, more to come? Wild temperature fluctuations do occur in Antarctica, a mass of ice and packed snow over land. The sea ice varies greatly too due to winds and strong ocean currents. February 2022 saw the lowest sea ice extent for Antarctica on record, with the minimum usually occurring in March so awaiting final data.
We’ve passed the Equinox; Antarctica is now heading towards winter and darkness. The Arctic would usually sea its maximum sea ice extent around this time and this year it was the 10th lowest on record using satellite records stretching back to 1979. It was also the tied 3rd (with 2015) earliest annual maximum extent, so largest on February 25th. Now in (northern Hemisphere) spring and heading towards summer there would be more thawing. It is unusual to see higher temperatures and melting at both poles at the same time because of these opposing seasons. Antarctica has just seen a record-breaking melt season. And the maximum Arctic ice extents have declined each decade “linked to warming caused by human activities such as emitting CO2” NSIDC
Russian station Vostok is famed for being the coldest place on earth with the world record from July 1983 of -89.2C. It has just seen its highest March record at -17.7C, beating the old record by 15C< this is unheard of. There are many base stations around the high dome area. French Italian Concordia had its highest March temperature of -12.2C, 40C above the norm. Australian Casey Station had a March record of =5.6C with melting ice. The British Terra Nova base reached =7.0C and the French Dumont d’Urville Base saw +4.8C, another monthly record fallen with sleet and rain.
As these values were being recorded it was unclear what was happening to the ice as there was a lot of cloud from the warm, moist flow of air. This high temperature event peaked around the 17th/18th March 2022 but the warmth stayed for several days. Afterwards, with clearer skies, an unusual collapse of the Conger ice shelf was seen to have happened. Also changes to the important Totten Glacier, the primary ice discharger of East Antarctica, it drains this area and holds in place a huge amount of ice.
What happened?
Winter warming events do occur, in the Arctic where temperatures peak above -10C occasionally. However, there are concerns that these will become more frequent and last longer and as March shows, become more intense and extreme.
Recent studies have shown that a circular process of warming in winter can impede ice growth and expansion which adds to global warming. Major storms can push warm moist air northwards to the Arctic or southwards to the Antarctic. This can stall ice formation but also break up the ice shelves which support the main flow of internal ice. Major ice release would raise sea levels around the world. Any wet snow onto the ice shelves complicates things further as some regions are usually very cold and very dry.
"The radiosonde launched by the colleagues on site shows the very atypical nature of the air mass. Northerly flow over the entire profile above 700hPa, extremely mild (iso -10°C at 4000m), tropopause at 200hPa, which is exceptionally high for the latitude." @GaetanHeymes Antarctica Mar 17th
Extreme and unusual flow of warm moist air sat in place to the Antarctic plateau and at the other end of the earth, to the Arctic. These are known as “atmospheric rivers”, a narrow corridor of warm water vapour, excessive moisture with warmth in the air. These dramatic changes in air flow stuck in place. The warm air continued to be advected towards the polar regions and so the conditions intensified
In the Arctic a deep low pressure moved across the NW Atlantic It moved from the US east coast to eastern Canada and set a new (unofficial) record for lowest pressure anywhere in Greenland. 934.1hPa (DMI) with a strong high pressure over Denmark at 1050hPa and as the low pressure was forced northwards it directed the atmospheric river. Svalbard saw rain and broke its March record with +3.9C
Photo - Therese Pedersen
For Antarctica, there was a stubborn intense high pressure to the SE of Australia and a deep low pressure over eastern Antarctica. The warm air and moisture were fed right down into Antarctica’s interior, where it remained, radiating heat down over the polar high ground. The cloud cover trapped any heat from radiating away. Our UK nights have been nippy this month because the warmth of the day leaves at night under clear skies.
Atmospheric rivers start at the edge of a low pressure and move large amounts of water long distances. This can fall as rain or snow. The atmospheric river to the Antarctic was really intense and large, astonishingly so with so much moisture. The moisture will take days to dissipate which is why the temperatures will also take their time to decrease.
“It was also an absurdly warm start for us here in Longyearbyen. +5 °C and rain when we arrived last Tuesday. In Kiruna, where #HALO is written, there was also a new Tmax record for March (9.1 °C) since records began yesterday.” Janosch M. @wetterkalle Mar 15th
A team of research scientists had been waiting in Kiruna, northern Sweden for such an event. HALO-(AC)³ is the field study that aims at investigating warm air intrusions into the Arctic and cold air outbreaks. They were able to fly their aircraft, called HALO, at the time. For both poles to be showing this kind of heating at the same time is unprecedented.
When the sea ice is disturbed, it can unleash blocked land ice, but it weakens the ice shelf edge. Thinner ice reforms, it is younger and not as robust. Arctic sea ice losses contribute to global warming. Incoming solar radiation is absorbed into darker surface water, not reflected back by bright white polar ice. The Arctic Sea ice is in retreat which affects wildlife and local people but also brings concerns about sea level. The sea level rise is the main worry for Antarctica and so it is alarming to see sudden ice shelf break ups.
Will there be more warming events, more extreme with more records falling? How will the ice shelf change and what about the frozen interior? These events might seem remote and diverting but scientists are asking that they add to the Wake up Call of addressing our changing climate.
Coldest ever recorded Vostok July 1983 -89.2C
Warmest for Antarctic continent (mainland and surrounding islands) Esperanza station Feb 2020 +18.3C
Coldest Arctic (and Northern Hemisphere) -69.6C Dec 1991 Greenland
Warmest Arctic record June 2020 +38C (100F) Verkhoyansk, Russia in a Siberian heatwave. The UK all-time record is also +38C (38.7C from 2019)
