A record temperature on the east side of Antarctica, after a warm summer, has caused controversy over its causes and effects among scientists.

On February 6, the Argentine research base Esperanza marked a temperature of 18,3 ° C, which exceeded the previous record of 17,5 ° C on March 24, 2015.

On King George Island, the total absence of rainfall during January has drawn attention. In fact, logistics and scientists from the Scientific Base Professor Julio Escudero, of the Chilean Antarctic Institute (INACH), said that no snow has fallen since Christmas.

“This is extremely irregular, and in almost 20 years of coming to the White Continent, I have never observed such a thing. Talking with researchers from other Antarctic bases, they point out the concern for freshwater reservoirs”, said the director of INACH, Marcelo Leppe.

INACH specified that warming encourages the growth and propagation of established plants, greater seed production and greater establishment of seedlings. Several studies have shown that climate change has increased the availability of areas that can be colonized by plants, as a result of reduced ice and snow cover and recession of glaciers along the Antarctic Peninsula. These changes were associated with increases in the reproductive capacity of both species, as a result of longer and warmer growing seasons.

In principle, this situation is attributed to the "Foehn" winds, a phenomenon similar to the Puelche or Raco wind, which causes record temperatures in the central zone of Chile, according to the academic of the University of Santiago, Raúl Cordero. The air is heated by being forced by the wind to go up and down the mountain range that covers the peninsula, with an average height of 1.500 meters.

"Although we know the mechanism that generates the record temperatures in the Antarctic Peninsula, we are still working to understand exactly why the Foehn winds have increased there, breaking more and more frequently the temperature records in the area," said Cordero.

The average annual temperature of the Antarctic continent varies from approximately -10 ° C on the coast to -60 ° C in the highest parts of the interior.

Extreme temperatures

Researchers know that climate change increases the frequency with which extreme events occur, including heat waves and extreme temperatures. Therefore, it is to be expected that records will be broken more and more frequently in Antarctica and throughout the world. "Unfortunately, it has been happening for decades," said the academic.

Cordero added that “in our research platform (annexed to the Escudero Base of INACH), the temperature during the summer has been around 1,5 ° C above the average in the same period during the last decade. The temperature on January 8 and February 7 was higher than 6 ° C and we had several days of unusual good weather. ”

According to INACH, all forecasts show a tendency to increase temperatures in polar areas, although the increase had been much more noticeable in the Arctic.

However, although there was already an episode in March 2015, what is surprising is "that the interval for a new temperature record is so short," admits its director.

According to INACH, there are varied reports of accelerated thaws in different regions of Antarctica, such as the Jorge VI channel, south of Margarita Bay, in the Chilean Antarctic Territory, verified through images taken by NASA's Landsat 8 satellite during January 2020.

In addition, it is known that tropical oceans influence the Antarctic climate through atmospheric teleconnections. These tropical impacts are more evident today in the Antarctic Peninsula and are mainly related to the tropical and subtropical Pacific Ocean.

The variability of El Niño events (ENSO) on interannual time frames is the most prominent influence. These tropical and polar forces govern the behavior of westerly drift winds around Antarctica that affect Southern Ocean circulation, sea ice extent, heat and carbon sequestration, and ocean biogeochemistry. “However, the megatrend shows a close link to anthropogenic global warming,” Leppe admitted.

Therefore, the frequent breaking of temperature records is not a result of chance. “They are a direct consequence of global warming. The rise in the average temperature increases the probability of occurrence of high temperatures and heat waves, ”said Lamb.

In that sense, a new temperature record could be possible and would depend mainly on the intensity of these local phenomena in summer conditions, in synergy with global warming, which is a process of remote origin.

"Although it is not possible to predict these events with certainty, it is more important to indicate that only due to the effect of global warming, it is likely that maximum temperature values ​​will be obtained more frequently on a seasonal scale," agreed the academic from the Universidad Austral de Chile. and researcher at the IDEAL center, José Luis Iriarte.

Impacts

Obviously, these rises in temperatures have an impact on the flora and fauna of the area, in addition to its water resources. "In the ocean, it can affect marine organisms, as well as icebergs that move through the affected area," summarized Iriarte.

There may also be a combined effect. The collapse of the Brunt ice shelf in the Weddell Sea offers a recent example of an extreme event that has removed the habitat of the second largest emperor penguin colony in the world.

Regarding the first point, the Antarctic region maintains some of the most iconic species on the planet –such as whales and penguins– and provides a wide range of important ecosystem services. “These events open up new habitats, especially for microorganisms. A water system, with greater solar radiation, higher temperature and nutrients, are the ideal conditions for the growth of microorganisms such as bacteria and microalgae”, affirmed the expert from the IDEAL center.

INACH specified that warming encourages the growth and propagation of established plants, greater seed production and greater establishment of seedlings. Several studies have shown that climate change has increased the availability of areas that can be colonized by plants, as a result of reduced ice and snow cover and recession of glaciers along the Antarctic Peninsula. These changes were associated with increases in the reproductive capacity of both species as a result of longer and warmer growing seasons.

However, the improvement of the conditions for the establishment of vascular plants, together with the increase in the arrival of human beings and the increase in temperature and rainfall in the Antarctic Peninsula region, are facilitating the arrival and survival of exotic species in the White Continent.

At the water level, according to Cordero, these high temperatures have immediate effects on snow and ice, causing huge melt losses. During this summer, via satellite images –Landsat8 and Aqua from NASA–, his team has detected huge pools or lakes (meltponds) on the surface of ice shelves on the east side of the Antarctic Peninsula.

"These pools, and depending on their magnitude, can cause mechanical damage to the ice shelves through deepening or perforation through the ice mass," explained Iriarte.

"Being darker than ice, the water in these lakes absorbs solar radiation, heats and drills the ice, causing what is known as hydrofracture," said Cordero. The academic also stressed that the melting relative to this event has been concentrated on the east coast of the Antarctic Peninsula.

Therefore, temperatures in Chilean bases have been far from those recorded in the Argentina Esperanza Base. While at the Esperanza Base the temperature exceeded 18 ° C, just 160 km away, at the INACH Escudero Base, where the TARP-02 research platform is located, the maximum temperature did not reach 4 ° C.

Future scenarios

Now the question is what will happen in the future if the temperature rises further.

Recently, during the development of the Chilean Congress of Antarctic Science, in September 2019, the researcher of the British Antarctic Survey, Huw Griffiths, said that if warming is projected over the next decades - an inevitable phenomenon if we follow the same behavior - the fund Marine will look very susceptible.

With an increase of only 0,5 ° C, it will be enough to stress the benthic life, which will seek refuge at greater depths or in waters further south. On a scale of 200 years, the picture is less auspicious, according to Griffiths. The Antarctic marine environment would be more suitable for subantarctic or South American species and not so much for native species.

A warming of 1 or 2 ° C will be a critical problem for these species, because their reproduction is very slow and they do so when they reach a very advanced age, so there will not be enough generations that can gradually adapt to environmental changes.

The INACH warns about a reduction of ecospaces for species less tolerant to warming and, in many cases, in extinction. Also a loss of mass from glaciers, rise in sea level, intensification of westerly winds, acidification of the oceans, the arrival of exotic species in Antarctica and, what is far less well known, the jeopardization of the capacity of the Antarctic continent to modulate the climate of the planet. “And especially from Chile, the closest nation to her,” Leppe said.