Taking a Fine-Grained Approach to Investigating Climate’s Impact on Crops

By Jane Palmer

Gradually rising temperatures, changing rainfall patterns, and extreme weather events are resulting in increasing losses in agriculture around the world, with rapid declines in crop production known as shocks.

To study climate change’s impacts on food and other crop systems, scientists have typically measured the change in crop yield in different weather scenarios. But when it comes to building a resilient food production system, it is valuable to look beyond this single metric, according to the authors of a new study published in Nature Sustainability.

Lead author and doctoral candidate Dongyang Wei of the University of Delaware said that tracking other elements that play a role in food production, such as how much crop can be planted in a given area, could also offer valuable insights regarding crop shocks. Wei studies issues of food security and climate change.

Digging Deeper

Crop production is calculated as the product of yield (crop per unit area) and the area of land harvested, which depends on how much land has been planted and what farmers and scientists term the “harvestable fraction”—the ratio of harvestable crop to planted crop. Each of these components—planted area, harvested area, and yield—can suffer losses independently and affect crop production, so the researchers analyzed how climate changes affected each one separately.

Wei, Davis, and their colleagues assembled agricultural data for seven major crops—barley, corn, cotton, sorghum, soybean, spring wheat, and winter wheat—in the United States between 1978 and 2020 and detected when shocks to crop production, yield, land planted, and the harvestable fraction had occurred.

Their analysis revealed that shocks in the amount of planted and harvested areas occurred at the same time as more than half of the production shocks. “Yield is important, but the data shows that other components are also important for crop production,” Wei said.

The team also analyzed how much the different components contributed to the size of production shocks for each major crop type. They found that for corn, cotton, soybean, and winter wheat, yield fluctuations played a greater role in production shocks than the other two components. Changes in planted and harvested areas play a more important role in the magnitude of production shocks for barley, sorghum, and winter wheat.

When looking at different climate impacts on the components, the researchers found that temperature increases most often led to co-occurrences of shocks on all three. But extreme weather events had a greater impact on crop production than did general climate variability. “These [events] are harder to forecast,” Wei said.

Knowledge Is Power

As climate change influences agriculture, and in turn food security, understanding how variations in yield, planted area, and harvested area affect crop production is critical to adaptation efforts. So far, resilience building has focused on stabilizing the yield component by developing drought-tolerant varieties of crops and improving the range of crops, for example. “But by looking only at yield you miss a lot of potential opportunities to adapt to climate variability and climate change impacts,” Davis said.

The findings show that factors related to planting and harvesting area are important when it comes to increasing resilience in food production systems, Davis said.