Future changes in temperature variability are larger than those over the last 1000 years

Global warming not only impacts mean temperatures but also temperature variability on multiple timescales, substantially altering climate extremes. We here show that already observed and projected human-caused changes in internal temperature variability are much larger than the variability caused by natural external forcings over the past 1000 years. We find that multiple estimates of temperature variability from paleo-proxies, observations and climate model simulations agree both in magnitude and distribution which underpins confidence in the projected changes. Despite regional differences, multiple large ensemble simulations consistently project a decrease in global-mean temperature variability, with strong increases over tropical land but with substantial decreases in high latitudes. The causal mechanisms for the contrasting pattern of temperature-variability change involve the loss of sea ice in high latitudes and changes in vegetation cover in the tropics. The findings strengthen the need for urgent climate-change mitigation to avoid substantial increases in temperature variability in the tropics.