Hotspots of Changes in Exposure to Multivariate Extremes at Different Global Warming Levels

It is now certain that human-induced climate change is increasing the frequency, intensity, and spatial extent of climate and weather extremes globally. While a number of studies investigated these characteristics of individual extremes, an IPCC risk framework-like holistic approach introducing the potential impacts of the changes in concurrent and multivariate extremes is more informative. By using CMIP6 climate projections, historical and future population estimates we assess the influence of human and climate change on four concurrent extreme events (heatwave–drought, warm nights–high relative humidity, extreme 1-day precipitation–wind, drought–warm days-low relative humidity) in the preindustrial period (1850-1900) and at four global warming levels (GWLs from +1 °C to +3 °C). Our results show that concurrent occurrences of the investigated extremes become 1.2 to 8 times more frequent for the 3ºC GWL. The most dramatic increase is identified for compound heatwave–drought events, with an eight-fold increase in subtropical countries, a seven-fold increase in northern middle and high latitude countries, and a five-fold increase in tropical countries, respectively. Additionally, the number of events per capita showing the contribution of climate change alone exhibits a dramatic increase in compound heatwave–drought and warm days–low relative humidity-drought events over the Mediterranean countries, Europe, China, Australia, Russia, the United States, and the Northern part of South America, emphasizing the potential risk increase in the case of lack of concerted effort to cut greenhouse gas emissions.