Climate change has increased drought risk by at least 20 times

Climate change increased the risk of drought by “at least 20 times” during the past summer in the northern hemisphere, according to a scientific report by the World Weather Attribution (WWA) published on Wednesday (5).

The drought, which has affected vast regions of Europe, China and the United States, is at risk of occurring every 20 years with the current climate, rather than every 400 years or even longer as in the past.

The WWA is a network of scientists that studies the relationship between extreme weather events and global warming.

The consequences of this drought impacted the agricultural sector in dozens of countries, with low harvests and difficulties that had repercussions on world markets.

This situation also favored forest fires and jeopardized electricity generation, particularly from hydro and nuclear sources.

Because of heat waves in the northern hemisphere (outside tropical regions), the likelihood of drought has multiplied by a factor of “at least 20,” according to the report.

This means that at a depth of one meter, forest and agricultural soils suffer from a lack of water that affects the roots of plants in an accentuated way.

“The exact numbers are uncertain,” admit the scientists, who work in prestigious institutes or bodies.

“The true influence of human activities is probably higher,” assesses the WWA.

The average temperature of the planet has increased by 1.2ºC since the pre-industrial era, according to studies by climatologists.

Experts at the European Joint Research Center had calculated that last summer the drought had been “the worst in 500 years”.

More frequent and more intense

“The summer of 2022 demonstrated how human-caused climate change increases the risks of agricultural and ecological drought in agricultural and densely populated regions of the northern hemisphere,” said Sonia Seneviratne, professor at the Institute for Climate and Atmospheric Science in Zurich, co-author of the study.

“We have to stop burning fossil fuels if we want to stabilize climatic conditions and prevent these episodes from getting worse again. They will become more and more frequent and intense with increasing warming,” she added.

In central and western Europe, the probability of drought is lower: between 5 and 6 times less important, according to calculations. This variability is due to the extension of the territory and the analyzed data.

“Usually, signals related to climate change are more important in larger regions,” said Friederike Otto of Imperial College London, another co-author of the study, when presenting it to journalists.

“When we look at smaller regions, we find more day-to-day variations in weather in the data,” but that effect “fades out” when larger regions are studied, she said.