Climate change made 2022 drought 'at least 20 times likelier'

Heatwave that caused record temperatures in Northern Hemisphere this summer could become a common occurrence, researchers say.

The Cantref Reservoir in Brecon Beacons National Park, Wales, where water levels dropped during the warm summer this year. PA.
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Human-induced climate change made this summer's drought across the Northern Hemisphere at least 20 times more likely, according to research.

The three months from June to August were the hottest in Europe since records began, and the exceptionally high temperatures led to the worst drought on the continent for centuries.

Researchers from World Weather Attribution, a group of scientists from around the world who study the link between extreme weather and climate change, said this type of drought would only happen once every 400 years if not for climate change.

Now they expect these conditions to repeat every 20 years, given how much the climate has warmed.

Successive heatwaves between June and July, which resulted in temperatures topping 40°C (104°F) in Britain for the first time, caused about 24,000 excess deaths in Europe.

China and North America also experienced unusually high temperatures and exceptionally low rainfall over the period.

“The 2022 summer has shown how human-induced climate change is increasing the risks of agricultural and ecological droughts in densely populated and cultivated regions of the North Hemisphere,” said Sonia Seneviratne, a professor at the Institute for Atmospheric and Climate Science at ETH Zurich in Switzerland and one of the study's contributors.

To quantify the effect of human-caused climate change on soil moisture levels, the team analysed weather data and computer simulations to compare the real climate as it is today, about 1.2°C hotter than pre-industrial levels.

They found that western and central Europe experienced particularly severe drought and substantially reduced crop yields.

Moisture in the top seven centimetres of soil across the Northern Hemisphere was made five times likelier to experience severe drought due to climate change, the study found.

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For the top one metre of soil, known as the root zone, this summer's dryness was made at least 20 times likelier due to global heating.

“Really, what is most relevant for agriculture and ecological impacts is the top one metre of the soil because that's where plants have their roots,” said Prof Seneviratne.

Overall, a Northern Hemisphere drought such as this summer's was now likely to occur once every 20 years in today's climate, compared to once every 400 years in the mid-18th century.

Producers in Europe and China have warned of significantly lower than expected harvests in crop staples due to the dry spell, after food prices hit multi-year highs following Russia's invasion of Ukraine in February.

Friederike Otto, senior lecturer in climate science at the Imperial College London, called the crop shortfall “particularly worrying”.

“It followed a climate change-fuelled heatwave in South Asia that also destroyed crops, and happened at a time when global food prices were already extremely high due to the war in Ukraine,” she said.

Otto said the Northern Hemisphere in general was showing a “pure climate change signal” in its overall warming trends.

Maarten van Aalst, director of the Red Cross Red Crescent Climate Centre and professor of climate and disaster resilience at the University of Twente, said governments needed to do far more to prepare for future heat and drought shocks, which will become ever more frequent as temperatures rise.

“We're talking tens of thousands of people killed by these phenomena and one thing that we are seeing is the impacts compounding and cascading across regions and sectors,” he said.

“It is playing out in front of our eyes even faster than we might have expected.”

Updated: October 06, 2022, 10:24 AM
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