Do CMIP6 Climate Models Simulate Global or Regional Compound Events Skillfully?

Compound events have the potential to cause high socioeconomic and environmental losses. We examine the ability of the sixth phase of the Coupled Model Intercomparison Project (CMIP6) models to capture two bivariate compound events: the co-occurrence of heavy rain and strong wind, and heat waves and meteorological drought. We evaluate the models over North America, Europe, Eurasia, and Australia using observations and reanalysis data set spanning 1980-2014. Some of the CMIP6 models capture the return periods of both bivariate compound events over North America, Europe, and Eurasia surprisingly well but perform less well over Australia. For heavy rain and strong wind, this poor performance was particularly clear in northern Australia which suggests limits in simulating tropical and extratropical cyclones, local convection, and mesoscale convective systems. We did not find higher model resolution improved performance in any region. Overall, our results show some CMIP6 models can be used to examine compound events, particularly over North America, Europe, and Eurasia. Plain Language Summary Compound events, such as the co-occurrence of heavy rain and strong wind or heat waves and drought, can have major economic, social, and environmental consequences. We therefore ask the question whether the new generation of climate models represented by the sixth phase of the Coupled Model Intercomparison Project (CMIP6) can simulate the occurrence of these important events. We found that some of the CMIP6 models do simulate these compound events surprisingly well over North America, Europe, and Eurasia. Unfortunately, they perform less well over Australia which is likely associated with the problem of simulating extratropical cyclones, local convection, and mesoscale convective systems. Our results suggest that some CMIP6 models can be used to examine these two compound events particularly over North America, Europe, and Eurasia. Key Points . Some CMIP6 models reproduce observed return periods of co-occurring rain and wind extremes and co-occurring heat waves and droughts well CMIP6 models simulate these compound events over North America, Europe, or Eurasia with similar levels of skill CMIP6 models simulate these compound events over Australia with lower skill than the other regions analyzed

Automated summary

The study evaluated the performance of CMIP6 models in capturing bivariate compound events and found that some models performed well in North America, Europe, and Eurasia, but less so in Australia. This discrepancy may be attributed to challenges in simulating cyclones, convection, and convective systems.