Abstract
The simultaneous occurrence of climate extremes significantly impacts ecosystems,
increasing the vulnerability to physical risks. Despite extensive research on hot
extremes and droughts globally, there remains a significant gap in comprehending the
occurrence, magnitude, spatial extent, and associated risks of compound extremes,
encompassing scenarios like warm/dry, cold/dry, warm/wet, and cold/wet. This study
investigates various compound extreme scenarios by examining combinations of
maximum temperature (Tx) and the Standardized Precipitation Evapotranspiration
Index (SPEI) using monthly data from 1951 to 2014 acquired from India Meteorological
Department (IMD) for Indian landmass. From the results, the spatial extent of warm/dry
events have increased at 1.8% per decade, while cold/wet events decreased by -1.1%
over India. The warm/wet events have shown an increased trend of about 0.3%, and
cold/dry events at modest rise of 0.7% per decade. Furthermore, compound warm/dry
and cold/wet extremes over India exhibit extreme frequency and shorter return periods,
posing greater risk. Conversely, compound cold/dry and warm/wet extremes occur less
often, indicating longer return periods and lower risk. Across much of the country, the
frequency of warm/dry, cold/dry, warm/wet, and cold/wet extremes ranges from 30-45,
15-30, 20-30, and 25-45 months, respectively. Notably, warm/dry conditions exhibit
increased frequency in the recent period (1983-2014) with 31 years compared to the
base period (1951-1982) which had approximately 24 years for a spatial extent
exceeding 5%. The findings of this study contribute to an enhanced understanding of
the changes in compound climate extremes from a multivariate perspective.
