Clim. Dynam. http://doi.org/6np (2015)

Credit: VIEW STOCK / THINKSTOCK

Recent summer heatwaves in Eurasia have caused significant water shortages as well as a large number of deaths. But the mechanism behind the year-to-year variability of these extreme weather events is not fully understood.

Zhiwei Wu, from Nanjing University of Information Science and Technology, China, and colleagues show that decreasing snow cover in the Tibetan Plateau could be playing an important role. They performed a set of numerical experiments with a global circulation model to examine the effect of varying snow cover in the plateau on heatwaves in Eurasia.

The authors identified a set of climate anomalies that are related to each other over large distances — a teleconnection pattern — prevailing over the mid- and high latitudes of Eurasia. Reduced snow cover on the Tibetan Plateau triggers the teleconnection, resulting in high-pressure anomalies over southern Europe and northeastern Asia. These high atmospheric pressures are associated with low cloud cover, which increases the radiation reaching the land surface, favouring more heatwaves in these regions.

With the expected decrease of Tibetan Plateau snow cover in the future, this teleconnection may be increasingly important in the development of heatwaves in Eurasia.