It has been very hot in Siberia for months, with several heat records broken. For example, a temperature of 38 degrees was recently measured within the Arctic Circle. New research uncovers the causes. Without global warming, the likelihood of such temperatures is almost endless.
The Arctic record was measured on June 20 in the Russian city of Verkoyansk, but according to climate researchers, the area has been dealing with exceptionally high temperatures all year round: from January to June it is on average 5 degrees warmer than normal. In the original climate, such persistent heat occurs only once every 80,000 years.
The probability that the temperature will deviate from 'normal' six months in a row has increased by at least six hundred times due to global warming. This means that even in the current, already warmed climate, the Siberian heat is extreme. It should occur about once every 130 years, unless it gets even warmer.
The probability of the polar record of 38 degrees has increased more. This can be at least several thousand times higher due to global warming. This is evident from analysis by World Weather Attribution, an international research network that was founded by the Dutch KNMI, among others, with the aim of reconstructing extreme weather situations. British, French, German, Swiss and Russian climate institutions are also involved in the analyzes.
Siberian temperatures statistically on the edge
"We can only determine the lower limits with good certainty in this calculation," KNMI co-author Geert Jan van Oldenborgh tells NU.nl. "In the method used, there is a threshold value for temperature deviations. The probability above this officially becomes zero and the Siberian temperature measurements are very close to that."
The specialists use a large number of global climate models for their research, which they run in two positions. A climate with the current, already warmed (on average about 1.2 degrees) and one of the 'pre-industrial climate', without great human influence.
It also shows that, without global warming, high Siberian temperatures could statistically occur only once every 80,000 years. "This heat is virtually impossible without human influence," the researchers concluded.
Heat also threatens to lead to further warming
The exceptionally high temperatures have persisted in Siberia for six months and this has major consequences. For example, large-scale melting is taking place of permafrost, an ice layer in the soil that should also remain below zero in summer.
The disappearance of permafrost can again release large amounts of greenhouse gases into the atmosphere. This chain reaction could further increase global warming by almost half a degree, according to other research last month.
The Siberian heat will also lead to large-scale wildfires this year, just like last year in the same area. At the end of June, more than a million hectares had already gone up in flames, with an estimated CO2 emission of 56 million tons of CO2. That is more than the annual CO2 emissions of Switzerland or Norway.
Van Oldenborgh: "Heat waves are getting warmer, which shouldn't surprise anyone. The upper limits of temperatures are shifting, so many places are now getting temperatures that have never happened before. Even Verkhoyansk will have to draw up a heat plan."
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