Climate-driven water scarcity increases wheat prices globally

A drought in one agricultural region can damage harvests. But what happens when severe water shortages affect several of the world’s major wheat-producing regions at the same time or follow one another over successive years? An international team of scientists has brought together climate observations, crop geography, global commodity prices and dozens of climate-model simulations to address this question. Their study reveals a strong connection between the extent of severe water scarcity across wheat-growing regions and the global price of wheat – a link that could become increasingly important as the planet warms.

The study, published in Earth’s Future, focuses on wheat because of its exceptional importance to the global food system. IIASA researchers contributed to the refinement of the research question and framing of the study, as well as providing advice on the modeling approach and data choices.

Wheat is grown across more land than either rice or maize, is a major source of calories and protein, and is one of the most internationally traded agricultural commodities. Much of it is also grown under relatively water-limited conditions. Until now, assessments of climate-change impacts on food prices have often concentrated on gradual changes in average crop yields. The new study, however, addressed a different question: Can the extent of drought during crop growth explain global cereal prices?

Putting the pieces together

Answering this question required researchers across climate science, agronomy, crop modeling and global food-system analysis to connect several pieces of the puzzle. The team first developed a globally applicable but crop-specific indicator called severe water scarcity (SWS). It combines short- and long-term water deficits and focuses on the four months before harvest, when crops are particularly sensitive to water shortages. Then they mapped these events across the areas where wheat, maize and rice are grown and compared the affected area with global commodity prices. The clearest signal emerged for wheat.

A model based only on severe water scarcity explained 74% of the year-to-year variation in global wheat prices between 2000 and 2021. Importantly, the model was developed without using data from 2022–2024, yet it still captured the broad wheat-price levels and changes during these years, providing an out-of-sample test under exceptionally turbulent market conditions.

For maize, severe water scarcity explained up to 40% of price variability, while no meaningful relationship was found for rice. One reason may be that wheat is generally produced under drier conditions and depends less on irrigation: only about 15% of the global harvested wheat area is irrigated, compared with about 33% for rice.

A climate signal that is already changing

Between 1911 and 2020, around 5% of the global wheat-growing area was affected by severe water scarcity in an average year. In 2000, 2010, 2012 and 2020, the affected area exceeded 15%.

The researchers then used simulations from global climate models to explore how this relationship could develop as the climate warms. The direction is clear: as warming increases, severe water scarcity becomes more widespread and estimated wheat prices rise. At around 2°C of global warming relative to 1951–1980, the model estimates an average wheat price of approximately US$ 273 per ton. At around 3°C, the estimate reaches approximately US$ 364 per ton – approximately three times the inflation-adjusted global wheat price in 2010.

“Previous studies suggested that international trade would play a key role in adaptation to climate change. However, the extent of severe water scarcity projected by the current paper and its implications for agricultural commodity prices mean that a profound transformation of the whole food system will be required so that it continues to provide affordable food also in the coming decades,” says IIASA Biodiversity and Natural Resources Program Director and study coauthor Petr Havlík.

Why it matters

The study does not suggest that drought alone determines wheat prices. It acknowledges that energy and fertilizer costs, grain stocks, exchange rates, trade policies, market expectations, pests and diseases, and geopolitical conflicts can all strongly influence food markets. However, the research identifies a climate-related signal that has so far been difficult to capture and quantify and the results indicate that indeed large-scale water scarcity across major production regions can propagate through the global wheat market.

This matters because wheat is not simply another commodity. It is a staple food for a large part of the world's population. When severe drought spreads across several major production regions, the consequences can travel far beyond the affected fields, through international markets to countries and households thousands of miles away.

The findings therefore suggest that future assessments of food security should look beyond gradual changes in average yields. They also need to consider large, recurrent and geographically connected water-scarcity events affecting several important production regions simultaneously or in close succession.

The research was led by Miroslav Trnka of the Global Change Research Institute of the Czech Academy of Sciences (CzechGlobe) and brought together scientists from research institutions across Europe and the United States.

The work also builds on the strong history of scientific collaboration between IIASA and CzechGlobe. Trnka is a long-standing IIASA collaborator, and researchers from the two institutions have worked together across areas including climate impacts and adaptation, ecosystems, and the Czech adaptation of IIASA’s Global Biosphere Management Model (GLOBIOM). The relationship was further strengthened during a CzechGlobe delegation visit to IIASA in December 2025, when researchers and institutional leaders explored opportunities to deepen scientific cooperation and future joint research on complex global challenges.

Reference 
Trnka, M., Meitner, J., Balek, J., Feng, S., Arbelaez Gaviria, J., Fischer, M., Boere, E., Havlík, P., et al. (2026). Climate‐induced severe water scarcity events as harbingers of global wheat price. Earth’s Future DOI: 10.1029/2025EF006095