Sensitivity of tropical precipitation extremes to climate change

Precipitation extremes increase in intensity over many regions of the globe in simulations of a warming climate(1-3). The rate of increase of precipitation extremes in the extratropics is consistent across global climate models, but the rate of increase in the tropics varies widely, depending on the model used(3). The behaviour of tropical precipitation can, however, be constrained by observations of interannual variability in the current climate(4-6). Here I show that, across state-of-the-art climate models, the response of tropical precipitation extremes to interannual climate variability is strongly correlated with their response to longer-term climate change, although these responses are different. I then use satellite observations to estimate the response of tropical precipitation extremes to the interannual variability. Applying this observational constraint to the climate simulations and exploiting the relationship between the simulated responses to interannual variability and climate change, I estimate a sensitivity of the 99.9th percentile of daily tropical precipitation to climate change at 10% per K of surface warming, with a 90% confidence interval of 6-14% K-1. This tropical sensitivity is higher than expectations for the extratropics(3) of about 5% K-1. The inferred percentage increase in tropical precipitation extremes is similar when considering only land regions, where the impacts of extreme precipitation can be severe.