Climate change made 2022 summer droughts at least 20 times more likely, study finds
made the droughts endured in the Northern Hemisphere this year up to 20 times more likely, a study has found. Greenhouse gas emissions were found to have played a key role in one of the hottest summers ever recorded in Europe, which completely dried out the soils. Climate scientists with the World Weather Attribution group collected soil moisture level data in June, July and August 2022 across a large area of our hemisphere. They detected a moisture deficit, and quantified it Sonia Seneviratne, professor at the Institute for Atmospheric and Climate Science at ETH Zurich, Switzerland, said: 'We need to phase-out the burning of fossil fuels if we want to stabilise climate conditions and avoid a further worsening of these drought events, which will become more frequent and more intense with any additional increase of global warming.' More than 24,000 heat-related deaths were recorded in Europe this year, while the continent's fires were the worst on record. The heat of the summer led to very dry soils, particularly in France, Germany and other central European countries. Droughts resulted in widespread water shortages, crop failures and impacts on electricity supply and food prices. To examine the effect of human-caused climate change on soil moisture deficits, researchers first analysed moisture levels in the soil in Western and Central Europe. This area experienced particularly severe drought with substantially reduced crop yields. They performed analysis on the top 7 cm of soil and for the top metre, the latter of which is known as the 'root zone' and is important for crops as it is where plants extract water. Soil moisture dryness in the root zone is often referred to as an indicator agricultural and ecological drought. The scientists then used historic weather data and modelling to discover how the climate has changed since the 1800s. This allowed them to discover to what extent the soil moisture deficit was the result of recent climate change. The findings revealed that climate change made surface drought at least five times more likely in the extratropical Northern Hemisphere. Drought in the root zone, indicating an agricultural and ecological drought, was also at least 20 times more likely. But, in West-Central Europe, the researchers said the warming made surface drought up to six times more likely, and root zone drought up to four times more likely. This does not mean climate change has a lesser impact in the continent, but the different sizes of the regions mean the results cannot be directly compared. Now, the experts claim that an agricultural drought like this summer's can be expected around once in 20 years in both West-Central Europe and the Northern Hemisphere as a whole. If humans had not warmed the planet, these would only be expected every 400 years in the hemisphere, and every 60 to 80 years in the continent. The study's authors claim that these are also likely to be conservative estimates of the frequency of severe droughts. This is because soil moisture has to be estimated, giving the results a wide possible range. It was found that the increase in temperature had the largest effect on soil moisture, and that changes to rainfall were less important. They concluded that the temperature rise across the Northern Hemisphere that resulted in a summer as hot as this year's would be 'virtually impossible' without climate change. It was also noted that the prevalence of soil moisture droughts will continue to increase with additional global warming, in line with reported climate models. Dominik Schumacher, researcher at the Institute for Atmospheric and Climate Science at ETH Zurich, said: 'Our analysis shows that last summer's severe drought conditions across large parts of the North Hemisphere were fueled by human-induced climate change. 'This result also gives us an insight on what is looming ahead. With further global warming we can expect stronger and more frequent summer droughts in the future.'