Megadroughts in the Common Era and the Anthropocene
We discuss shared causes and features of Common-Era and future megadroughts. Paleoclimate reconstructions spanning the Common Era document the occurrence of megadroughts on every continent, save Antarctica. Anthropogenic climate change has already contributed to recent megadroughts and will likely increase future megadrought risk and severity in many regions. Future megadroughts will be differentiated from past events through higher temperatures, which act as the main driver of increased risk and severity in climate projections.
We provide an assessment of important challenges that must be addressed to move megadrought research forward, including the paucity of high-resolution paleoclimate information over some regions, incomplete representations of internal variability and land-surface processes in climate models, and the undetermined capacity of water-resource management systems to manage megadrought impacts. Resolving these will be necessary to increase confidence in projections of future megadrought risk.
Exceptional drought events, known as megadroughts, have caused major ecological and societal disturbances in the past. While most megadrought research has focused on North America, the concept has gained increased international attention in recent years. However, several knowledge gaps currently undermine confidence in our understanding of past and future megadroughts, which we address detail.