Especially in Siberia, the temperatures were up to ten degrees Celsius above normal.

The temperatures we experienced last June were similar to those of June last year. That’s according to new figures from the Copernicus Climate Change Service (C3S). And that while June 2019 had entered the books as the warmest June month ever recorded worldwide. The Arctic in particular has been hit hard this year, where unprecedented temperatures have been recorded.

June was remarkable for several reasons

• The temperature was the same as that of June 2019, the warmest June on record. The average temperature was 0.53 degrees Celsius higher than the average was in the same month between 1981 and 2010.
• The Siberia region experienced the highest temperature anomalies, both for June and the past 12 months
• In northern Europe, temperatures were well above average and in southern Europe below average

The most striking was the exceptional warmth in Siberia. When you think of Siberia, you usually think of icy cold. But this year, remarkably mild temperatures appeared on the scene. For example, the average temperature in June was up to ten degrees Celsius above the normal temperature for that month. The average temperature across the entire landscape in the Arctic of Siberia was more than 5 degrees above average, and more than one degree higher than in 2018 and 2019, the two former warmest June months.

Siberian heat wave

In May, Copernicus already reported a long period of higher than average temperatures in Western Siberia. That trend started in December 2019. Remarkably, the temperature in the month of June in Western Siberia was mainly below average, which illustrates the large variability of the vast Siberian region once again. Meanwhile, on June 20, the mercury rose to as much as 37 degrees Celsius in some places in eastern Siberia. On the same day, a record temperature of 38 degrees Celsius was set. This new record-breaking June temperature is 1 to 2 degrees Celsius higher than previous record temperatures in the Arctic, which lasted for days in 1969 (in Alaska) and 1973 (in Eastern Siberia).

According to Carlo Buontempo, director of C3S, it is not so easy to pinpoint the causes for these record temperatures. “There are many factors that are related,” he explains. “Siberia and the Arctic Circle in general have large annual fluctuations and have experienced other relatively warm June months before.” Still, Buontempo worries. “What is particularly worrying is that the Arctic is warming faster than the rest of the world. It is unusual for Western Siberia to be warmer than average for so long in winter and spring. The exceptionally high temperatures in the Arctic of Siberia, which have now occurred in June 2020, are also worrying.”

Wind pattern

Researchers have identified an important factor for the mild winter and spring temperatures in Western Siberia and the high summer temperatures in the Arctic of Siberia. This is partly due to other, but relatively structural large-scale wind patterns. The C3S data also indicate that snow cover and humidity of the ground surface in the Siberian Arctic reached a record low in June 2020. This probably also played a role in the unusually high temperatures in the region.

Fires

The low moisture content in the soil is also likely to be a contributing factor to the intense fires that mainly plague the northeast of Siberia. The number and intensity of the forest fires in the Russian Republic of Sakha and Autonomous District of Chukotka – and to a lesser extent parts of Alaska and the Yukon areas – have increased since the second week of June. This has resulted in the highest estimated emissions in the CAMS’ 18-year dataset. A total of 59 megatons of CO2 were emitted into the atmosphere before June. Last year it was 53 megatons in the same month.

“What is remarkable about these fires in Siberia is the striking similarity to what we saw in the same period last year,” said researcher Mark Parrington. “Both in terms of the affected area and the extent of the fires. Last year was already by far an unusual and record summer for burning in the Arctic Circle in our Global Fire Assimilation System dataset, dating back to 2003. This year it has developed in a similar way. If this trend continues as it did last year, we will see intense activity in the coming weeks.”

The high temperatures in Siberia can have far-reaching consequences for the region – and also the rest of the world. For example, researchers are concerned that the high temperatures lead to the accelerated thawing of the permafrost. And the thawing of this permanently frozen subsurface until recently may lead to the release of large amounts of methane. In addition, it could be that the warm air also moves towards the north pole and possibly even towards Greenland. And that can lead to an accelerated melting of the sea ice and the Greenland ice sheet.