Reply on RC2

Abstract

Listen

Translate article

It is now certain that human-induced climate change is increasing the incidence of extreme temperature, precipitation and drought events globally. A critical aspect of these extremes is their concurrency that may result in substantial impact on society and environmental systems. Therefore, quantifying compound extremes in current and projected climate is necessary to take measures and adapt to future challenges. Here we investigate pre-industrial and projected changes of individual and concurrent extremes using multi-model simulations of the 6th phase of the Coupled Model Intercomparison Project (CMIP6). We focus on individual and simultaneous occurrence of extreme events: heat wave, drought, maximum 1-day precipitation (Rx1day) and extreme wind (wind) in the pre-industrial period (1850–1900) and at four global warming levels (GWLs of +1 °C, +1.5°C, +2 °C and +3 °C). We find that, on a global scale, most investigated individual extremes become more frequent and affect more land area for higher GWLs. This increase differs depending on the considered months and implies both unprecedented shifts in timing and disproportional increases in frequency of concurrent events for different climate regions. As a result, concurrent occurrences of the investigated extremes become 2.7 to 8.1 times more frequent for a GWL of 3 °C. At +3 °C the most dramatic increase is identified for concurrent heat wave-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. Our results also suggest that years without any individual events will decrease six-fold while the number of years with two concurrent events will double. Given the projected disproportional frequency increases across GWLs and decreasing non-event years, our results strongly emphasize the risks of uncurbed greenhouse gas emissions.