Climate change is creating new drought hotspots – even where rainfall is increasing
Scientists have long expected that global warming would bring more rainfall overall. But new research shows a troubling contradiction: in many parts of the world, soils are drying out – even in places that are projected to get wetter. This means more regions are becoming vulnerable to agricultural drought, posing rising risks to food production.
Soil moisture – not just rainfall – is what crops actually rely on. And global climate models show that declining soil moisture is already detectable in many parts of the world, with major implications for farming and water management. Climate scientists have now identified which regions across the tropics and Northern Hemisphere are emerging as hotspots for drought.
Why are soils drying out?
Soil moisture depends on more than just precipitation. It’s shaped by evaporation (which increases as temperatures rise), runoff (which can reduce how much water sinks into the ground), vegetation changes (as plants respond to heat and carbon dioxide levels), and snowpack decline (which reduces slow-release water in spring).
As the planet warms, the atmosphere “pulls” more water out of the soil. This means that even if a region gets more rain, it may lose soil moisture faster than it gains it, leading to long-term drying.
Unlike broad annual drought measures, agricultural drought is defined by soil dryness during a region’s growing season – the only months that matter for most crops. In the extratropics (including Europe, US, China) growing seasons peak in late spring and summer, whereas in the tropics they occur during local wet seasons.
Soil moisture at the start of the season is just as important as rainfall during the season itself. Because soil moisture “remembers” past conditions, dry starts lead to dry seasons, increasing crop stress.
With more frequent and severe spells of dry weather – climate change is already intensifying the risk of drought around the world.
How are climate models used to understand drought?
By focusing on soil moisture at the start of each growing season, and how rising global temperatures affect evapotranspiration, the UK research team have used computer modelling methods to simulate drought under different societal conditions and climate change projections.
The team’s projections of future impacts of climate change on drought are consistent with today’s real-life observed mechanisms for drying, and highlight how the increasing frequency of drought is also made worse by shifts towards more severe droughts – they are happening more often and more intensely.
We linked global warming effects to changes in the land-surface water balance, which meant we were able to identify emerging drought hotspots around the world. Our approach captures drought hotspots that are overlooked by standard methods, which look at annual data, rather than with each growing season.
– Professor Emily Black, a climate and terrestrial processes scientist, at the National Centre for Atmospheric Science and University of Reading.
Where are the emerging drought hotspots?
The research identifies several regions where agricultural drought is expected to worsen significantly. In western North America and Europe the spring soil moisture (March–May) is projected to decline sharply. Past droughts, such as the devastating 2018 European summer drought, align with these trends. These regions are now considered high‑risk drought hotspots.
Western Southern Africa is emerging as a major hotspot, with water scarcity expected to intensify. Both observations and model projections agree that rainfall is decreasing in this region, and its “Day Zero” drought (2015–2017) is linked to climate change.
In Amazonia and northern South America, models and real-world data show a persistent rise in drought frequency and intensity. Four “once‑in‑a‑hundred‑year” events have occurred in the past two decades, and global warming is amplifying El Niño-related rainfall shortages. This region is a severe emerging hotspot with profound risks to ecosystems and agriculture.
What do droughts mean for food and water security?
“The changes are concerning for global food production, because intense dry spells can devastate crops and severely reduce yields. Our study alerts policymakers to crop stress that will increase across Europe, North America, southern Africa, and northern South America, as well as in many tropical regions where communities are particularly vulnerable,” explains Professor Emily Black.
It also advises that the demand for irrigation water would likely rise, so water scarcity could also sharply limit agricultural production in many regions – calling for drought‑resistant crops, smarter water management, and improved soil conservation.
These findings have strong implications for food security and highlight the need for drought-resilient adaptation, not only in the global south, but also in extratropical regions where risk is already escalating.
Learn more about the research
The research team includes scientists from the National Centre for Atmospheric Science, National Centre for Earth Observation, University of Leeds, and University of Reading.