And because air-conditioners work in part by venting hot air outside, they also make the surrounding neighborhood warmer. By some estimates air-conditioning can raise overnight temperatures by about two degrees Fahrenheit (one degree Celsius) in some cities, the report said. Practically speaking, if enough of your neighbors buy an air-conditioner it may increase the temperature in your home enough to drive you to do the same.
And then, of course, there’s climate change. India is already one degree Fahrenheit warmer on average than it was a century ago. This has led to more “cooling degree days,” or days when average temperatures are warm enough to necessitate air-conditioning.
“If you look at cooling degree days for Chennai or Mumbai, these are places that have twice as many cooling degree days as the hottest city in the U.S., Miami,” said Lucas Davis, director of the Energy Institute at the Haas School of Business of the University of California, Berkeley. “It’s unbelievably hot — there’s nothing in the U.S. that compares in terms of heat to these cities in India.”
And when it gets hot, forgoing air-conditioning can be deadly. The heat wave that plagued Chicago in 1995 killed more than 700 people, while the 2003 European heat wave and 2010 Russian heat wave