Projected Hydroclimate Changes on Hispaniola Island through the 21st Century in CMIP6 Models

Climate change might increase the frequency and severity of longer-lasting drought in the Caribbean, including in Hispaniola Island. Nevertheless, the hydroclimate changes projected by the state-of-the-art earth system models across the island remain unknown. Here, we assess 21st-century changes in hydroclimate over Hispaniola Island using precipitation, temperature, and surface soil moisture data from the 6th Phase of the Coupled Model Intercomparison Project (CMIP6). The resulting analysis indicates, as with the previous 5th Phase of CMIP (CMIP5) models, that Hispaniola Island might see a significant drying through the 21st century. The aridity appears to be robust in most of the island following the Shared Socioeconomic Pathways (SSP) 5-8.6, which assumes the "worst case" greenhouse gas emissions into the atmosphere. We find a significant reduction in both annual mean precipitation and surface soil moisture (soil's upper 10 cm), although it appears to be more pronounced for precipitation (up to 26% and 11% for precipitation and surface soil moisture, respectively). Even though we provide insights into future hydroclimate changes on Hispaniola Island, CMIP6's intrinsic uncertainties and native horizontal resolution precludes us to better assess these changes at local scales. As such, we consider future dynamical downscaling efforts that might help us to better inform policy-makers and stakeholders in terms of drought risk.