Estimating the sensitivity of continental aridity to global warming using Budyko’s framework

Understanding the sensitivity of continental atmospheric aridity, the ratio of potential evaporation to precipitation in Budyko’s framework, to changes in temperature can help in quantifying the changes in the hydrological cycle and its extremes like droughts and floods in response to global warming. With rising temperature, land warms up faster than the ocean due to its different response of surface energy balance to diurnal changes in solar radiation. Thus, the potential evaporation, which represents atmospheric moisture demand, increases more over the land than the ocean. At the same time, global warming induced changes in the temperatures over land and ocean regions can alter the moisture supply to the atmosphere affecting the precipitation over land. Therefore, the sensitivity of continental atmospheric aridity to global warming is a superposition of relative changes in continental potential evaporation and precipitation in response to rising temperatures in both land and ocean regions. This work introduces an analytical framework based on Budyko’s aridity index to quantify the historical changes in continental aridity, and its sensitivity to global warming. We evaluate the proposed framework using observation-based datasets and our preliminary findings suggest that while changes in both potential evaporation and precipitation contribute to increase in the continental aridity with global warming, the relative changes in potential evaporation contribute more than relative changes in precipitation. These results point to the importance of considering both facets of aridity and highlight the utility of the Budyko’s framework in evaluating changes in hydrological cycle amid global warming.