The atmosphere's growing "thirst" for water has made droughts across the globe 40% more severe, new research shows.
While lack of rainfall is often thought to be responsible for droughts, scientists have discovered the atmosphere itself is demanding more water out of soil, rivers, and plants.
This phenomenon, known as Atmospheric Evaporative Demand (AED), acts like an invisible sponge, soaking up moisture faster than it can be replaced, increasing water stress, particularly for plants.
As the world gets hotter under the effects of climate change, AED is rising, causing more severe drought events even in wet regions, according to the international team.
Their study, published in Nature, is the first to measure the global impact of AED using real-world observations to better predict and prepare for droughts.
The team, which included expertise from Cardiff University, used a set of high-resolution data covering more than a century for their analysis.
They tracked how AED has increased and how much worse it has made droughts over this period.
Their results show:
- AED has increased global drought severity by about 40% over the past 40 years
- wet regions are affected by more severe droughts because the atmosphere is demanding more water from the land, not just because of less rainfall
- the extent of land under more severe drought conditions jumped by 74% in the last five years, largely driven by the atmosphere's growing thirst.
One of the study's co-authors Professor Michael Singer of Cardiff University's School of Earth and Environmental Sciences, said: "Although everyone understands that the climate is changing through a warming atmosphere, it is unclear how this impacts climatic extremes like droughts and floods."
Our study provides clear evidence that AED has increased, leading to more severe drought conditions, which could impact various sectors, lives, and livelihoods across the globe.
Deputy Director of the Water Research Institute
Lead author Dr Solomon Gebrechorkos of Oxford Univeristy's School of Geography and the Environment, added: "This work shows that including AED in drought monitoring-rather than relying on precipitation alone-is essential for better managing risks to agriculture, water resources, energy, and public health.
"Given projected climate changes, especially rising temperatures, the impact of AED is expected to intensify. Many affected areas are already struggling to cope with severe drought."
We need to act now by developing targeted socio-economic and environmental adaptation strategies and improved early warning and risk management systems.
Scientists will need to study how farmers, cities, and ecosystems can adapt to a world where the atmosphere constantly demands more moisture, according to the team.
More studies focused on climate driven fluctuations in AED will also improve drought prediction, they conclude.
The paper, 'Warming accelerates global drought severity' is published in Nature.
