Strong regional trends in extreme weather over the next two decades under high- and low-emissions pathways

Global warming is rapidly shifting climate conditions away from what societies and ecosystems are adapted to. While the magnitude of changes in mean and extreme climate are broadly studied, regional rates of change, a key driver of climate risk, have received less attention. Here we show, using large ensembles of climate model simulations, that large parts of the tropics and subtropics, encompassing 70% of current global population, are expected to experience strong (>2 s.d.) joint rates of change in temperature and precipitation extremes combined over the next 20 years, under a high-emissions scenario, dropping to 20% under strong emissions mitigation. This is dominated by temperature extremes, with most of the world experiencing unusual (>1 s.d.) rates relative to the pre-industrial period, but unusual changes also occur for precipitation extremes in northern high latitudes, southern and eastern Asia and equatorial Africa. However, internal variability is high for 20 year trends, meaning that in the near term, trends of the opposite sign are still likely for precipitation extremes, and rare but not impossible for temperature extremes. We also find that rapid clean-up of aerosol emissions, mostly over Asia, leads to accelerated co-located increases in warm extremes and influences the Asian summer monsoons. Large-ensemble simulations suggest that strong regional trends in precipitation and temperature extremes will be common over the next two decades, even under stringent mitigation measures.