Source: AGU Advances
A heatwave in Siberia starting in January 2020 led to a cascade of events resulting in temperatures reaching 38◦C (100◦F) in June. The winter heatwave caused an early snow melt which elevated the soil moisture. This in turn caused earlier spring greening. As the heatwave persisted, soil moisture evaporated causing soil to be drier and trees to brown earlier in summer. Since the soil was drier than normal, the heat emanating from it was elevated which further exacerbated the heatwave. Gloege  report that this line of evidence suggests that large-scale dynamics and land-atmosphere interactions both contributed to the magnitude and persistence of this record-breaking heatwave, in addition to the background changing climate effects on mean temperature. With Arctic temperatures increasing twice as fast as the global average, the role of land-atmosphere interactions will likely become more prominent in the future as the climate warms.
Citation: Gloege, L., Kornhuber, K., Skulovich, O., Pal, I., Zhou, S., Ciais, P., & Gentine, P. . Land-atmosphere cascade fueled the 2020 Siberian heatwave. AGU Advances, 3, e2021AV000619. https://doi.org/10.1029/2021AV000619
—Don Wuebbles, Editor, AGU Advances