Challenges for assessing the risk of compound extremes

The effects of compound extremes (for example, Compound dry hot extremes (CDHE)) in a region simultaneously are more adverse than those of individual dry or hot events. The likelihood of such events depends on the marginal distribution of drivers and their dependence. An approach to assess CDHE probability is urgent because of their frequent occurrence caused by global warming. This study shows how CDHE probability changes with the selection of reference period. We considered the WMO recommended period 1961-1990 and a recent climate normal 1991-2020 to show the effect of the reference period on the likelihood. We applied the framework to homogenous regions of India during the monsoon season. Insights show that CDHE is more likely to occur in arid regions than in other climatic regions. The results of this study are useful for further exploration and provide new insights into the emerging changes in CDHE.