Investigating the Influence of Fallowed Agricultural Lands on Nearby Surface Temperature in California’s Central Valley

Monitoring changes in land surface temperature (LST) in agricultural regions is crucial for identifying the exposure of both cropland areas and neighboring communities to excessive heat. Variations in agricultural land use have substantial impacts on LST. Agricultural practices such as fallowed lands – where agricultural lands are unplanted and not irrigated – can potentially lead to elevated LST beyond the extent of local land use. Although many studies focus on how the temperature increase due to climate change impacts agricultural lands, none has examined how fallowed lands may indirectly influence the LST of nearby agricultural lands or how they may reduce crop yield. This study explores the potential influence of fallowed lands on LST dynamics in surrounding agricultural areas in California’s Central Valley. Using 30-m resolution fallowed land data from the U.S. Department of Agriculture’s Cropland Data Layer (CDL) and LST information derived from Landsat 8 satellite between 2013-2022, we analyzed spatial and temporal variations in LST associated with fallowed land areas. Our preliminary findings suggest that fallowed lands contribute to elevated LST in adjacent agricultural regions, suggesting that such agricultural practices may influence local microclimates. Specifically, fallowed lands exhibit higher LST compared to their nearby cultivated counterparts, with the temperature disparity decreasing away from the fallowed areas. This pattern suggests that fallowed lands have heat impacts that extend beyond local scales, which may inform subsequent thermal impacts to adjacent cropland and communities. Additionally, aerosols, such as dust emitted during farmland practices, may play a role in exacerbating LST near these fallowed areas, enhancing its impact on nearby areas. Overall, our research underscores the importance of land management practices in agricultural regions and their broader implications for local climate adaptation.