The research team focused on soil moisture during the main growing seasons rather than on annual average rainfall or soil moisture, which can conceal critical seasonal patterns that drive crop outcomes. By combining historical climate data with computer model simulations, the scientists identified emerging hotspots of agricultural drought under climate change, highlighting western Europe, including the United Kingdom and central Europe, western North America, northern South America and southern Africa as regions of particular concern.
Professor Emily Black, lead author at the University of Reading, said: "Climate change is heating the air, which makes more water evaporate from soil and plants. This dries out fields even when more rain falls, especially during spring in Europe and North America." She added that the timing of drying is crucial for agriculture because it affects plant growth and yield during sensitive stages of crop development.
The study finds that soil moisture levels in spring, at the start of the growing season, play a decisive role in determining drought risk later in the summer. Warmer conditions increase evaporation from soil and vegetation, so even where spring precipitation increases, the extra heat can remove water more quickly than rainfall can replenish it. As a result, spring drying persists into summer, leaving crops exposed to longer and more severe dry spells.
Recent severe European droughts, including the events in 2003, 2010 and 2018, all followed unusually dry conditions in spring or early summer, illustrating how early-season soil moisture deficits can set the stage for damaging summer droughts. The new analysis indicates that as global temperatures continue to rise, this pattern is likely to repeat more often, amplifying drought frequency and severity in the coming decades across regions that produce a significant share of the world's food.
The researchers also examined how different greenhouse gas emissions pathways influence future drought risk. They report that following lower-emission climate trajectories would lessen the increase in agricultural drought frequency across vulnerable regions compared with higher-emission scenarios, but would not fully prevent more frequent and intense drying of crop soils. This finding underscores the importance of both climate mitigation and adaptation strategies for global food security.
According to the authors, farmers and policymakers will need to plan for a future in which agricultural drought becomes a more common challenge even in areas where mean annual rainfall does not decline. Adaptation options highlighted by the study include developing and deploying crop varieties that can tolerate drier conditions and improving water management practices, such as more efficient irrigation and better soil moisture conservation.
By focusing on growing-season soil moisture rather than annual averages, the research reveals drought risks that traditional precipitation-based assessments may miss. The results suggest that climate risk assessments and agricultural planning should explicitly account for seasonal soil moisture changes under warming, especially during spring, when conditions can lock in the likelihood of summer droughts.
The study, published in Nature Geoscience, provides a framework for identifying regions where warming-driven soil drying will outpace any gains in rainfall. The authors conclude that without substantial reductions in greenhouse gas emissions combined with targeted adaptation in agriculture and water management, many of the world's key food-producing regions are likely to face increasingly challenging drought conditions over the course of this century.
Research Report:Emerging hotspots of agricultural drought under climate change
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