CLIMATE CHANGE: A heat wave in the coldest place on earth: What does a 40 degree rise in Antarctica mean? | Science & Technology

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A few days ago, an unprecedented temperature record was set in Antarctica. The Franco-Italian research station Concordia, located at over 3,000 meters above sea level on the Antarctic Plateau, the coldest place on earth, recorded a temperature of 40°C above average. Temperatures around -55ºC are usual at this time of year, but on March 18th the mercury reached -12ºC. Cold, but not nearly as cold as one would normally expect. Although there was no ice melt, images transmitted by the Sentinel satellite showed high temperatures on Totten Glacier and its surrounding shoreline, and darker snow, indicating older strata. Meanwhile, on the other end of the planet in the Arctic, a heatwave was recorded, with temperatures up to 30C above the March average and no sunlight.

Both Antarctica and the Arctic are breaking temperature records and challenging even the most pessimistic climate change models. By the end of the century, scientists predict that even in a moderate climate change scenario, the number of polar heat waves will double in most of West Antarctica and triple in the far interior of East Antarctica. These predictions were published in nature, and recent events have done little to counter them. Higher temperatures are also becoming increasingly common in the Arctic.

A colony of chinstrap penguins on Half Moon Island, Antarctica.Shutterstock

The consequences are well known: Scientists are predicting catastrophic polar ice melt that will not only raise sea levels across the planet, but will also disrupt ocean currents and thus life as we know it by upsetting the fragile ice balance West Antarctica and the Arctic at risk.

“In general, both pole surges are related to climate change, but they are not linked; It’s normal for them to coincide in time because they’re becoming more common in the Arctic, but what’s amazing is their width, especially in Antarctica. Forty degrees off the average is a lot,” says researcher Raúl Cordero of the University of Santiago, Chile, and one of the authors of the nature Paper.

This is not an isolated case either. Cordero notes that on January 7, a temperature of 11.4 °C was measured at Argentina’s Belgrano II research station in the Weddell Sea, and a month later, on February 8, another large rise was measured in the Antarctic Peninsula ( 13.7 °C at South Korea’s King Sejong base and up to 12 °C at Ukraine’s Vernadsky research base), which led to the collapse of a 3,800-square-kilometer ice shelf. Although those temperatures fall short of a record 18.2C recorded two years ago, given that this southern summer saw the fewest ice floes seen in the region in 45 years, experts are not optimistic about the overall panorama.

“Heat waves can cause significant ice melt and an increase in rain and snow. In the interior of Antarctica this means more snow, but on the coasts it brings rain and melting, which is happening now. Looking ahead, more snowfall is expected, but melting will also increase significantly more. These episodes also increase the instability of the ice cliffs: the heat melts the snow inside, and when it refreezes it puts pressure on the walls and breaks them up. All this can accelerate the loss of ice mass. In Antarctica, projections predict that sea levels will rise by one meter to 1.7 meters by 2100,” says University of Aveiro researcher Irina Gorodetskaya and lead author of the sixth assessment report published by the Intergovernmental Panel on Climate Change (IPCC).

Just days after the heat wave, satellite images confirmed that the 1,200-square-kilometer Conger Ice Shelf in East Antarctica had completely collapsed. The shelf has been weakening over time, and experts say recent high temperatures may have been the last straw.

The scientific explanation for this latest heat wave, in an area where the effects of climate change have been less pronounced, lies in atmospheric fluxes. It is noteworthy that not far from the Concordia research station is the Russian Vostok station, where 40 years ago the lowest temperature ever recorded on Earth was recorded: -89 ° C. “East Antarctica has always been cold, but in this case it brought an atmospheric flow of warmer and wetter air from Australia to Dome C, where Concordia is located, and it became trapped, causing a microgreenhouse effect,” says Cordero.

“These warm puffs of air don’t usually spread that far due to a wall of circumpolar winds from the west preventing them from penetrating. “Now the hole in the ozone layer is strengthening those winds and in March this wall is strengthening as well. It needs to be investigated, but what is significant is the frequency of this type of event; At the end of the day, there are more heat waves than cold waves and even if there were no global climate change, their numbers would remain the same.”

Even when it comes to specific episodes, it is the frequency of these anomalies and their intensity in recent years that is ringing alarm bells and experts fear that even the current climate change models compiled in the IPCC reports are so could aim low against the situation on the ground. “As we have seen with this recent Antarctic heat wave, I would say that the models are very conservative and the reality shows that climate change is not an issue of the future but of the present. These extreme events are still not well understood and climate models may underestimate them,” says Gorodetskaya.

In any case, climate change in Antarctica is nothing new. Thirteen of the 17 meteorological stations that have recorded temperatures for more than 30 years have already registered an increase in their annual averages, and researchers predict that by the end of the 21st century, the duration of heat waves in East Antarctica will increase from nine to 25 days per year Season will increase from nine to 18 days in the Western Peninsula. Temperatures will also increase by up to 5°C, although they are expected to remain below zero in the interior of the Antarctic plateau.

Johnson Glacier on Livingston Island during a February 2020 heatwave.
Johnson Glacier on Livingston Island during a February 2020 heatwave.Rosa M Tristan

“The projections show that polar heat waves will not only increase in the future, but that every fraction of a degree of global warming will matter: the extreme temperatures that occur once every 50 years in a climate without human influence could all now 10 years, and with global warming of two degrees, they will be 14 times more frequent,” says Gorodetskaya. Despite these forecasts, the pollutant emissions that cause these climate events continue to increase worldwide, and the current international context does not suggest that drastic measures will be taken in the foreseeable future.

“If that 40-degree difference had occurred on the Antarctic Peninsula, there would have been an ice melt in just a few days that would normally take years,” says Francisco Navarro, a glacier expert at the Technical University of Madrid. Navarro points to the melting caused by the 2020 heatwave in the glaciers he’s been monitoring on Livingston Island for decades. “The thermal wave can penetrate to a depth of 15m within a year, and if it persists, the problem is even greater.”

The Arctic heatwave comes as less of a surprise as it is already in an alarming state of melting at almost three times the rate of the rest of the planet. There, these temperature increases have a direct effect on the inhabitants and the native fauna of the region and increase the risk of forest fires. The Siberian Arctic recorded 38°C in 2020 and in Greenland mercury rose to 23.4°C during a heatwave a year later. This year, in the middle of winter and without daylight, almost 0 °C was reached in some areas.

The longer we wait, the greater the impact will be and the longer the irreversibility will last

Researcher Irina Gorodetskaya from the University of Aveiro

“In the Antarctic, the effects are not immediately so sensitive, but the fauna is also suffering. In addition, we lack understanding of the so-called high-impact, low-probability episodes, such as B. a sudden collapse of the West Antarctic ice sheet, but the consequences of sea level rise and destabilization of the climate system will be enormous. if not catastrophic,” says Gorodetskaya, who will travel to the region in a few days on a research mission in the German-built High Altitude and Long-Range Research Aircraft (HALO). “We will fly along the warm air pockets to measure the transformation of this air mass along its path. I want to study the transition from snowfall to precipitation in atmospheric flows in the Arctic and Antarctic,” says the scientist. The HALO was recently used to fly through a “river of warm air” that reached Greenland from Canada.

Whether we can return to a pre-global warming situation in the polar regions, Gorodetskaya is not optimistic. “We can slow it down, but the response of the Antarctic system is irreversible. Even if it can be slowed or stopped, the impact will continue for another 100 or even 1,000 years. Every additional degree of temperature and every heat wave commits several future generations to so-called negative emissions, i.e. reducing carbon in the atmosphere, even long after man-made emissions have reached zero. Changes in Arctic sea ice are reversible as they vary linearly with global surface temperatures; there is no turning point. But the longer we wait, the greater the impact and the longer the irreversible period will be.”

All experts agree that research needs to continue to better understand these phenomena and their impacts in the Arctic and Antarctic, but also that action to curb the emissions they cause is of paramount importance.

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