The authors find that climate change increased the intensity and probability of all 213 heatwaves in the study. Similarly, 2000-09 heatwaves were 1.4°C hotter due to human-caused climate change on average, according to the study, while 2010-19 heatwaves were made 1.7°C hotter. This second scenario is used to represent the climate in a world without human-caused climate change. They then compared the likelihood of crossing the threshold temperature in the world with – and a world without – climate change. The discrepancy is due to differences in the definition of the event, as well as its “very unlikely nature” according to the study authors.)