The Effects of Climate on Global Changes in Cropland Extent: Historical Patterns and their Implications for the Future

Abstract

Climate change is altering the global agricultural landscape, impacting land suitability and driving changes in yield, management, profitability, and even land use. Climate-driven changes in cropland area have the potential to greatly impact food security, environmental health, carbon storage, and climate; however, the magnitude and scale of cropland responses remains poorly characterized. This study combines remote sensing cropland data products based on MODIS and Landsat with ERA5 climate reanalysis data to evaluate how cropland extent changed in regions of changing climate from 2001-2018, and then applies the derived climate-cropland relationships to estimate future climate pressure on cropland from 2015-2050. Over the study period, global cropland area negatively correlated to temperature, with cropland area decreasing by 3%-4% per °C warming. Precipitation, vapor pressure deficit, and potential evapotranspiration all also significantly correlated to cropland change. These relationships were dependent both on the underlying climate and on the rate of change of the cropland; croplands in transition were more strongly correlated to climate factors. After the key linear cropland-climate relationships were identified, they were further stratified by crop type, management (irrigation and fertilization rates), and economic classification. The coefficients of these linear relationships were then used to calculate the climate pressure, or the estimated potential land-use change if the observed partial temperature and precipitation effects were to hold true from 2015-2050 under the high emissions Shared Socioeconomic Pathway (SSP) scenario 5-8.5. Precipitation exerted strong pressure at sub-regional scales, but had little cumulative global impact, since projected trends were highly localized and relatively balanced between gain and loss. Temperature, on the other hand, exhibited a strong negative pressure over global cropland, amounting to a global pressure of reduction -2.5% of baseline 2015 cropland between 2015-2050. This was comparable in magnitude but opposite in direction to the Integrated Assessment Model-projected cropland change included in the Land Use Harmonization 2 (LUH2) SSP5-8.5 scenario, which projected a global increase of 3.7% baseline area per decade, without considering the impacts of climate on crop production. Though the partial temperature effects identified do not account for compound effects from other climate changes or socioeconomic factors, they nevertheless indicate a strong temperature pressure on cropland change that may not be captured by current integrated modeling systems. This study identified regions where climate pressures may significantly alter cropland area change projections, and highlights the importance of considering climate in the evaluation of agricultural land-use change. Better accounting for the observed role of climate changes, and particularly temperature, on cropland area change will be critical to improve future cropland projections.