Biophysical feedback of grassland-cropland conversion on regional climate in the U.S. Great Plains

Authors: LIU, WENQI - Oklahoma State University; ZHOU, YUTING - Oklahoma State University; YOU, NANSHAN - University Of Minnesota; DONG, JINWEI - Chinese Academy Of Sciences; YANG, HAOXUAN - Tongji Medical College; Flynn, Kyle; Wagle, Pradeep

Submitted to: American Geophysical Union Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 10/4/2023
Publication Date: N/A
Citation: N/A

Interpretive Summary: The interaction between land surfaces and the atmosphere is the primary way human activities affect climate. Anthropogenic changes in land cover currently play a key role in the exchange of energy and greenhouse gases in the earth-atmosphere interaction. These changes can alter land conditions and create feedbacks that affect the regional climate. In the past 15 years, the U.S. Great Plains region has experienced substantial grassland-cropland conversion, with plenty of natural grasslands converted to agricultural fields including corn, sorghum, winter wheat, and spring wheat. These land cover changes have altered the land surface biophysical characteristics. However, the feedback of these land conversions on regional climate is still unclear. Here, we explored the biophysical feedback of grassland-cropland conversion on regional climate by utilizing both the Cropland Data Layer (CDL) data and remote sensing datasets. We found that conversion from natural grassland to cropland modified the land surface temperature (LST) of the local climate. Significant cooling effects were detected before the ripening stage during crop growing seasons. This phenomenon was demonstrated in the grass-corn, grass-sorghum, grass-spring wheat, and grass-winter wheat land cover conversion patterns. When LST changes induced by the common land conversion types that happened in both regions were compared, the cooling effects generally occurred earlier in the southern than in the northern Great Plains. The northern Great Plains showed a more intense reduction in LST. We conclude that converting grassland to cropland has a heterogeneous impact (i.e., varies depending on the specific region) on regional climate.

Technical Abstract: The interaction between land surfaces and the atmosphere is the primary way human activities affect climate. Anthropogenic changes in land cover currently play a key role in the exchange of energy and greenhouse gases in the earth-atmosphere interaction. These changes can alter land conditions and create feedbacks that affect the regional climate. In the past 15 years, the U.S. Great Plains region has experienced substantial grassland-cropland conversion, with plenty of natural grasslands converted to agricultural fields including corn, sorghum, winter wheat, and spring wheat. These land cover changes have altered the land surface biophysical characteristics. However, the feedback of these land conversions on regional climate is still unclear. Here, we explored the biophysical feedback of grassland-cropland conversion on regional climate by utilizing both the Cropland Data Layer (CDL) data and remote sensing datasets (MYD11A2, MCD43A3, and MOD16A2). We found that conversion from natural grassland to cropland modified the land surface temperature (LST) of the local climate. Significant cooling effects were detected before the ripening stage during crop growing seasons. This phenomenon was demonstrated in the grass-corn, grass-sorghum, grass-spring wheat, and grass-winter wheat land cover conversion patterns. Additionally, non-radiative process alteration (represented as evapotranspiration changes) dominated the LST change in the growing season. The biophysical feedback varied between the northern and southern Great Plains. When LST changes induced by the common land conversion types that happened in both regions were compared, the cooling effects generally occurred earlier in the southern than in the northern Great Plains. The northern Great Plains showed a more intense reduction in LST. We conclude that converting grassland to cropland has a heterogeneous impact (i.e., varies depending on the specific region) on regional climate.