Amplification of Extreme Hot Temperatures over Recent Decades

While global warming is mostly conceptualized in terms of increases mean temperature, changes the most extreme conditions encountered often have disproportionate impacts. Here, a measure amplification defined as change highest yearly temperature (denoted TXx), representing heat, minus that 80th percentile daily high (Tmax80), which represents typical summer conditions. Based on ERA5 reanalysis, over 1959–2021, TXx averaged 1.56 K land areas, whereas Tmax80 1.60 K. However, population-weighted significantly exceeded (implying positive amplification) Africa, South America, and Oceania. Where available, station observations generally showed similar trends to ERA5. These findings provide new target for climate model calibration insight evaluating changing risk extremes.