Global temperate drylands climate change vulnerability

Drylands cover 40% of the global terrestrial surface and provide important ecosystem services. While drylands as a whole are expected to increase in distribution and aridity in coming decades, temperature and precipitation forecasts vary by latitude and geographic region suggesting different trajectories for tropical, subtropical, and temperate drylands. Uncertainty in the future of tropical and subtropical drylands is well constrained, whereas soil moisture and ecological droughts, which drive vegetation productivity and composition, remain poorly understood in temperate drylands. Here we show that, over the 21st century, temperate drylands may contract by a third, primarily converting to subtropical drylands, and that deep soil layers will be increasingly dry during the growing season. These changes imply major shifts in vegetation and ecosystem service delivery. Our results illustrate the importance of appropriate drought measures and, as the first global study to focus on temperate drylands, highlight a distinct fate for these highly-populated areas. The data are outputs from the SOILWAT ecohydrological model, which was applied in a grid over 6 temperate drylands across the globe (South America, Southern Africa, Eastern Asia, Western and Central Asia, Western Mediterranean basin, and North America. Simulations were conducted for two time periods: 1980-2010 and 2069-2099.