Impacts of climate change on global meteorological multi-year droughts using the last millennium simulation as a baseline

Abstract

Multi-year droughts have been widely studied all over the world for their extraordinary long duration and irreparable impacts. However, they are difficult to be estimated due to the short period of observed time series, especially in the context of climate change and on a global scale. The advanced development of climate model simulations with a long period makes it possible to investigate the multi-year drought change on a global scale. Therefore, this study quantifies the impacts of climate change on global meteorological multi-year droughts for the historical period (1850–2005) and the future period (2006–2100) using the pre-industrial last millennium period (850–1849) as a baseline. Meteorological droughts longer than 5-year are identified using a three-dimensional (latitude-longitude-time) method based on a 12-month scale Standard Precipitation Index (SPI12). Return periods are estimated using tri-variate copulas based on drought duration, area, and severity. The results show that multi-year droughts occur more in North America, South America, Asia, and Africa, accounting for more than 85% during 850–2100. The return period of 61% and 70% multi-year droughts for the historical and future periods becomes shorter than that for the last millennium, indicating more severe drought conditions for these two periods. The main change for the future period is the higher incidence of multi-year droughts with a longer duration and greater severity, especially for North America, Asia, and Africa. Besides, the shift of multi-year drought centroids in Central America, East Asia, Southern Africa, and the Mediterranean implies more severe drought conditions for the future period. Overall, this study indicates that climate change has the potential effects to exacerbate global meteorological multi-year droughts for the future period compared to the last millennium.