How Do Projections of Meteorological Droughts Vary Across Models and Regions?

Abstract

Quantifying how and where climate change will alter meteorological drought properties is a priority to inform adaptation policies. Here we use the standardized precipitation index to portray future changes in the climatological properties of moderate drought events projected by the latest generation of Earth system models. Beyond the assessment of their mean frequency and intensity, other metrics are explored including length of drought intervals, drought duration, starting date and severity. Two extended 6-month seasons are distinguished starting in October and April, respectively. Consistent changes in drought properties are projected across timescales and seasons. Regional “dry spots” are identified, such as northern South America and the Caribbean Islands, where the median model response shows the largest increase in drought severity, mostly as a result of prolonged duration. Yet, there are many regions where the inter-model spread remains substantial and cannot be reduced by the application of global and regional observational constraints.