A 2-3 fold increase in heatwave activity since the late 1800s is found in the Central England Temperature record. Crossing theory provides estimates of average heatwave properties from the observed cdf. These are plotted versus time in years, where a heatwave is defined as consecutive days with maximum summer daily temperatures above a threshold. For heatwaves at a threshold of 28
C, the UK threshold for building overheating, we see a 2-3 fold decrease in the return period of a 6 day long heawave (panel a) and a 2-3 fold increase in the duration of a heatwave with an average 5 year return period (panel b). The temperature threshold of a 6 day long heatwave with 5 year return period has increased, from being typically below 28C to typically above it (panel c).
Credit: AGU