Urban Heat Waves Likely to Hit Harder

Rob McDonald of the Nature Conservancy shares his thoughts on an evolving threat. "I was struck by how frequently big cities get hit by a bad heat wave: from Chicago in 1995 to Moscow in 2010 to London today. While for any particular city bad heat waves occur only infrequently, there are several cities globally facing one every summer."

Causalities were especially high during the European heat wave of 2003. "In France, the most impacted country, there were 11,000 deaths. The total for all Europe was greater than 70,000 dead. [...] The event produced "so many bodies that the morgues were full, requiring other refrigerators in a vegetable market to be commandeered."

The trend toward severe weather, says McDonald, can be attributed to climate change. "[...] these kind of extreme heat waves will become more common. One study for the U.S. predicted a four-fold increase in the number of days with extreme heat by 2050."

McDonald suggests ways cities can mitigate the danger. These include emergency cooling centers located near those at risk (such as the elderly) as well as more urban green space. He writes, "by providing shade the trees reduced the 'urban heat island' effect, the tendency for cities to be generally hotter than the surrounding countryside [...] trees and other vegetation also cool the air in cities because they transpire water into the atmosphere," storing excess heat away from ground level.