Disastrous back-to-back heatwaves and droughts surge across Eurasia

Over the past two decades, swathes of Eurasia – from Ukraine’s breadbasket to cities in northern China – have seen a spike in extreme heatwaves followed by droughts. A tree ring record extending back nearly three centuries suggests human-caused climate change is to blame for the increase in these disastrous compound events.

This pattern can be especially damaging because of how heat and drought feed off each other: high temperatures dry out soil, and drought then deprives it of moisture to cool things off during the next heat wave. This vicious cycle has devastating impacts, from lower agricultural yields to higher wildfire risk.

While parts of Eurasia have seen this heatwave-drought pattern before, “the present trend is just way outside of natural variability”, says Hans Linderholm at the University of Gothenburg in Sweden.

The full picture only became clear after Linderholm and his colleagues assembled tree ring records, which preserved temperature and precipitation conditions since 1741, from across Eurasia. They used this to reconstruct the large-scale distribution of high and low-pressure systems that naturally drives wet and dry conditions across the continent.

The researchers found a particular scenario in this region, which they call the “trans-Eurasian heatwave-drought train”, has markedly intensified since 2000, with the size of heat and precipitation anomalies jumping above those measured at any other time in the record. They link this change to disruptions in atmospheric pressure caused by heating in the North Atlantic and increased rainfall in part of northern Africa – both of which are associated with anthropogenic climate change.

Rising local temperatures can also directly exacerbate extreme heat and drought. But the new finding shows how climate change is also shifting relationships between distant parts of the atmosphere – known as teleconnections – to disrupt things even more, says Linderholm.

The team’s projections, based on climate models, suggest things will get worse under all but the lowest emission scenarios. “We see that this new teleconnection pattern has a really distinct strong trend, which means things will most likely go quicker, and there will be more severe impacts,” says Linderholm.

“We have difficulty seeing how [the most affected places are] going to recover,” he says.