2025 Climate Review: How Water Stress Episodes Are Reshaping the Global Map of Agricultural Yields

The year 2025 ranks as the 2nd or 3rd warmest year ever recorded, according to the Copernicus Climate Change Service. With global temperatures reaching +1.18°C above the 20th-century average, it confirms a worrying trajectory that now affects agricultural regions across all continents.

Beyond temperature records, it is the repeated occurrence of intense heatwaves and water deficits during critical crop development stages that has profoundly shaped global agriculture. From Europe to North America, including Brazil, broad acre crops have faced particularly challenging conditions, with contrasting impacts depending on regional contexts and adaptive capacity.

FAO (Food and Agriculture Organization of the United Nations) figures are telling: nearly 2 billion people now live in regions where agricultural yields are declining.

For farmers, 2025 represents a very real economic reality, marked by significant yield losses in certain areas and increasing pressure on production systems.

Maize: a global crop with highly variable outcomes

Maize, a major global crop, perfectly illustrates the contrasts of 2025 across regions and production systems.

In Europe, spring 2025 will be remembered as exceptionally dry. Nearly 40% of the European Union territory was already under alert by spring. Germany recorded its driest March ever measured, while the United Kingdom experienced its hottest and driest spring since 1893. Summer then brought its own set of challenges: Western, Southern, and South-Eastern Europe experienced drier-than-average conditions throughout the entire season.

In France, maize paid the heaviest price, with yields ranging from 87.5 to 88.5 q/ha, representing a -8.2% decrease compared to 2024. Two heatwaves (June 19 to July 4 lasting 16 days, then August 8 to 18) occurred precisely during flowering and grain filling. Evapotranspiration reached 9 mm/day (+4 mm versus normal), while water deficits exceeded 150 mm in Western and Central regions. Rainfed maize was particularly affected (~77 q/ha), with losses of 20 to 30% in Poitou-Charentes, Pays de la Loire, Limousin, Burgundy, and the South-West. Irrigation requirements reached up to 268 mm, i.e. +50 mm versus the average.

In South-Eastern Europe, the Joint Research Centre confirms irreversible losses. Eastern Hungary, Southern Romania, and Bulgaria experienced repeated heatwaves combined with persistent water shortages, resulting in yields well below the five-year average. Germany, Poland, and Western Hungary performed better, benefiting from more favorable rainfall distribution.

In the United States, despite extreme climatic conditions, maize achieved a record yield of 186.0 bushels per acre, with total production reaching 16.8 billion bushels (+12% versus 2024). This remarkable performance highlights the effectiveness of intensive irrigation and well-adapted agricultural practices in overcoming climate challenges.

In Brazil, production increased by 23.5% to reach a record 141.6 million tonnes, despite La Niña conditions and irregular rainfall, confirming the strong adaptive capacity of the Brazilian agricultural sector.

Key takeaways:

Soybean: vulnerability during the pod-filling stage

Soybean showed particular sensitivity to water deficit episodes during its critical pod-filling stage.

In France, with yields of 23.7 q/ha (-9.2% vs 2024) and total production of 356,000 tonnes (-0.5%), soybean was heavily impacted by summer water stress during pod formation.

In the United States, soybean achieved a record yield of 53.0 bushels per acre, although total production declined slightly by 3% to 4.25 billion bushels, reflecting a modest reduction in planted area.

In Brazil, soybean set a historic record with 166.0 million tonnes (+14.5%), consolidating the country’s position as the world’s leading producer and demonstrating remarkable resilience under variable conditions.

Key takeaways:

Sunflower and cereals: timing makes the difference

Sunflower

Sunflower showed relatively better resilience. In France, yields reached 21.7 q/ha (+10.7% vs 2024), thanks to better natural tolerance and a crop cycle that avoided the most critical periods. However, in South-Eastern Europe, sunflower was heavily impacted in areas affected by repeated heatwaves.

Cereals

Cereals benefited from a favorable calendar. Their early growth cycle took place before the most intense summer events. In France, soft wheat reached 74 q/ha (+18% vs 2024) and barley increased by 12%. At the European level, wheat production is expected to reach 140.4 million tonnes, up sharply from 125.5 million tonnes the previous year, marking a return to normal yield levels after 2024.

Key takeaways:

What made 2025 particularly challenging was not so much the absolute intensity of events, but their timing. Each crop has phases of maximum sensitivity:

• Maize: flowering and grain filling (July–August) – stress at these stages leads to poor ear filling and limits dry matter accumulation
• Soybean: flowering and pod formation – water shortage results in flower abortion
• Sunflower: flowering and achene filling – its deep root system nevertheless provides better resilience
• Cereals: stem elongation and grain filling (May–June) – their early cycle allowed them to avoid the most severe summer conditions

The impacts go beyond yield: shortened grain-filling periods, reduced photosynthetic efficiency, and in some cases quality losses (lower protein levels in cereals).

A long-term global trend

Climate change and agriculture

The year 2025 should not be seen as an isolated anomaly, but rather as an illustration of an underlying trend. A study published in the Proceedings of the National Academy of Sciences shows that global wheat yields would be 10% higher without the impact of warming over the past 50 years (Lobell & Di Tommaso, 2025).

The increasing frequency of adverse climate events is no longer a projection, but a current reality affecting all continents. What Météo France describes as a “typical summer pattern of the recent climate” is becoming increasingly common on a global scale.

Uneven adaptive capacity

The year 2025 highlights significant disparities in adaptive capacity. The United States and Brazil have shown that well-equipped agricultural systems can maintain, or even improve, performance despite challenging conditions. By contrast, less equipped regions have suffered more severe impacts, with local yield losses of 20 to 30%.

This reality raises a major challenge:

How can all production systems be enabled to adapt to increasing variability and more frequent stress episodes?