Heatwave · Arctic Siberia
The summer the Arctic reached 38 °C
Verkhoyansk lies just north of the Arctic Circle, in a valley of north-eastern Siberia where winter nights fall below −60 °C. On 20 June 2020 its thermometer read 38.0 °C. The World Meteorological Organization later recognised it as the Arctic's highest temperature on record. [N1] The day was the peak of half a year of heat: from January to June, Siberia was more than 5 °C warmer than average, a stretch of warmth that a study found would have been almost impossible without human-caused climate change. [S1]
January – June 2020 · Sakha (Yakutia), Russia · ERA5
38.0°C
Verkhoyansk, 20 June 2020
The highest temperature on record north of the Arctic Circle, recognised by the WMO in 2021.N1
600×
More likely with climate change
At least, for the six months' heat, and more than 2 °C hotter than without human influence.S1
+6.3°C
June 2020 at Verkhoyansk in ERA5
19.5 °C against a 1991–2020 normal of 13.2 °C.
What happened
The warmth began in winter. In ERA5, every month from February to June 2020 was warmer than normal at Verkhoyansk, by 2 to 6 °C. Snow melted early, the ground dried, and when June brought a block of high pressure over north-eastern Siberia, the heat had nothing to slow it down.
Wildfires burned across Yakutia that summer. The six months of heat, a study found, would have been almost impossible without human-caused warming; it was at least 600 times more likely and more than 2 °C hotter because of it. For the single day at Verkhoyansk the study is less certain, though there too warming made such a record far more likely.S1
| Month | 2020 | Normal | Difference |
|---|---|---|---|
| February | -34.5 | -38.5 | 4.0 |
| March | -21.6 | -25.3 | 3.7 |
| April | -5.8 | -10.1 | 4.3 |
| May | 5.4 | 3.6 | 1.8 |
| June | 19.5 | 13.2 | 6.3 |
The ridge
On 20 June a closed ridge stood over the Yana basin, the 500 hPa surface near 5,760 m, a height more usual over the Mediterranean in summer. Under it the air sank and warmed, skies were clear, and the sun, which does not set at Verkhoyansk in June, heated the ground almost around the clock.
Verkhoyansk
35.7°C
ERA5's highest temperature at Verkhoyansk on 20 June, 2.3 °C below the station's 38.0 °C. Its grid cell takes in the hills around the valley, where the air is cooler.
A warm half-year
The single day matters less than the months. On the Lab's map of spring (March to May 2020) the whole of Yakutia is milder than usual; in June the mean temperature at Verkhoyansk was 6.3 °C above normal.
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References
News
- N1World Meteorological Organization. WMO recognizes new Arctic temperature record of 38°C. 14 December 2021.The WMO's recognition of the 38.0 °C record.
Studies and guidelines
- S1Ciavarella, A., et al. (2021). Prolonged Siberian heat of 2020 almost impossible without human influence. Climatic Change, 166, 9.The six months' heat and how much more likely climate change made it.