Last May, I had the dubious fortune of visiting Mumbai, India during the city's hottest month on record. Temperatures remained at over 40 degrees Celsius for days at time. The difference between standing in the shade of a tree and standing in full sunlight was like night and day.
Such heat waves are not merely uncomfortable. They pose a serious health threat — one that is often overlooked when addressing extreme weather.
In fact, heat waves account for more deaths than any other type of weather-related event, killing more than 12,000 people worldwide each year. The danger is particularly pronounced in cities, where the "urban heat island" effect results in temperatures as much as 12 C higher than in less-developed areas nearby. And the issue is not confined to tropical cities like Mumbai. In August 2003, a devastating heat wave across Europe killed more than 3,000 people in Paris alone.