A team of researchers, led by scientists from the University of New South Wales, compared temperatures on the same calendar days between 1979 and 2012, and classified the hottest ten per cent as extremely hot days. They found that globally, the average number of such days that different regions experienced was 36.5. During the period under study, regions that experienced ten, 30 or 50 extremely hot days above this average saw the greatest upward trends in both the number of extremely hot days over time and the land area that was affected.

Overall, the results also indicated that, on average, extremely hot events affected more than twice the area affected by similar events 30 years ago. ‘Our analysis shows that there has been no pause in the increase of warmest daily extremes over land, and that the most extreme of the extreme conditions are showing the largest change,’ said one of the paper’s authors, Markus Donat. ‘Those regions that normally saw 50 or more excessive hot days in a year [also] saw the greatest increases in land area impact and the frequency of hot days. In short, the hottest extremes got hotter and the events happened more often.’

This story was published in the April 2014 edition of Geographical Magazine