Ever since she was an undergraduate student studying at the National University of Sciences and Technology (NUST) in Pakistan, University of Delaware doctoral candidate Afia Sarwar was interested in climate change and its impacts on crops and agriculture.

Part of that had to do with a general curiosity, but another part had to do with her home country, as Pakistan is greatly impacted by climate change due to its location, severe weather patterns and high reliance on farming.

“That was one of the reasons that I started working on this topic back when I was an undergraduate and then I continued studying it for my master’s degree,” said Sarwar. “I came to UD and to the United States in spring 2023 and here, I'm continuing to work with Kyle Davis on the impacts of climate change on agriculture.”

That work has led to the recent publication of a paper titled “Entrenchment of cropping patters reinforces climate exposure for certain crops in US,” in Environmental Research Letters.

Davis, an associate professor with joint appointments in UD’s Department of Geography and Spatial Sciences and the Department of Plant and Soil Sciences and a resident faculty in UD’s Data Science Institute, and Bhoktear Khan, who earned his doctoral degree from UD in 2026, served as co-authors on the paper.

The study analyzed county-level time-series data from 1981-2019 for ten major crops, including corn, soybean, peanuts, and winter wheat, across the United States to quantify how climate conditions have shaped cropping patterns and climate exposure.

Rather than focusing solely on crop yield, the researchers examined harvested area, the total land area from which a crop is harvested at maturity.  Food production depends on how much area a farmer plants and how high crop yields are, but only the latter has been studied in relation to climate influences.

They also differentiated between rainfed and irrigated crops.

The main finding was that climate impacts are more pronounced for rainfed crops than for irrigated crops, and that climate change affects not only crop yields but also the areas where crops are harvested.  

Ongoing changes in harvested areas—through shifts in both crop types and water management strategies—are reshaping climate pressures faced by U.S. croplands. Because of climate change, areas that once grew a certain crop now grow something else. For example, fields that once grew rainfed winter wheat now grow irrigated corn or soybeans.  

“This is important because climate change is a real thing, and farmers adapt to climate change by relocating their crops,” said Sarwar. “We cannot ignore that farmers are not going to continue to grow the same plants in the same area because they keep changing according to the changing climate.”

Sarwar added that the techniques they used to write this paper can also be applied globally, and she is working to apply them to her home country.

“For my next project, we are planning to extend this study globally,” said Sarwar. “So, I will be able to study the impacts of climate in different regions of the globe, including Pakistan.”