Climate extremes indices in the CMIP5 multimodel ensemble: Part 2. Future climate projections

TLDR

This study reviews projected changes in climate extreme indices defined by the ETCCDI. Indices are computed consistently across CMIP3 and CMIP5 simulations for various emission scenarios, and changes are analyzed globally and regionally for the 21st century relative to 1981–2000. Daily minimum temperature indices change more than daily maximum ones; extreme precipitation rises faster than total wet days, with regions such as Australia, Central America, South Africa, and the Mediterranean experiencing increased consecutive dry days and reduced heavy precipitation, especially under RCP8.5, though model disagreement exists for some precipitation indices.

Abstract

This study provides an overview of projected changes in climate extremes indices defined by the Expert Team on Climate Change Detection and Indices (ETCCDI). The temperature‐ and precipitation‐based indices are computed with a consistent methodology for climate change simulations using different emission scenarios in the Coupled Model Intercomparison Project Phase 3 (CMIP3) and Phase 5 (CMIP5) multimodel ensembles. We analyze changes in the indices on global and regional scales over the 21st century relative to the reference period 1981–2000. In general, changes in indices based on daily minimum temperatures are found to be more pronounced than in indices based on daily maximum temperatures. Extreme precipitation generally increases faster than total wet‐day precipitation. In regions, such as Australia, Central America, South Africa, and the Mediterranean, increases in consecutive dry days coincide with decreases in heavy precipitation days and maximum consecutive 5 day precipitation, which indicates future intensification of dry conditions. Particularly for the precipitation‐based indices, there can be a wide disagreement about the sign of change between the models in some regions. Changes in temperature and precipitation indices are most pronounced under RCP8.5, with projected changes exceeding those discussed in previous studies based on SRES scenarios. The complete set of indices is made available via the ETCCDI indices archive to encourage further studies on the various aspects of changes in extremes.