Engineers at the University of California, Irvine have learned that urban centers with more than 5 million inhabitants and parts of Eurasia and Australia have been hardest hit by the accelerated growth in short-term, extreme-heat events, resulting in lost lives, reduced agricultural productivity and damage to infrastructure.
In a paper appearing in the American Geophysical Union journal Earth's Future, the researchers report that their analysis of temperature readings from the most recent 50- and 30-year periods rules out the possibility that natural climate variability is to blame for the mercury rising.
"The global average annual temperature has increased over the past three decades at a rate of 0.20 degrees Celsius per decade, but we have found that the maximum temperature of the year has climbed at a much faster rate - two to three times higher in such regions as Eurasia and parts of Australia and more than three times higher in some megacities," said Efi Foufoula-Georgiou, UCI Distinguished Professor of civil & environmental engineering and senior author on the study.
"These results are alarming and yet more evidence of the harsh impact of global warming being felt by people around the world today."
Looking at thermometer readings for the 50-year period ending in 2015, they saw an average international increase in short-term highest temperatures of 0.19 degrees Celsius per decade; the growth accelerated to 0.25 degrees per decade in the 30 years from 1986 to 2015.
More than just temperature readings on a map, these events have taken a severe human toll: A heat wave in Europe in 2003 caused roughly 70,000 deaths, and another in Russia in 2010 killed nearly 55,000 people.