How do you cool 7.5 billion people on a warming planet? This feature explores how rising temperatures across India are forcing millions to calculate whether they need to invest in air conditioning to combat the risks associated with extreme heat. The share of Indians with air conditioning is still small, roughly 5 percent, but it’s growing fast. Rising incomes are making air conditioners more attainable, while rising temperatures are making them a necessity. “There are hundreds of millions of people for whom air conditioning doesn't seem like a luxury good,” said Michael Greenstone, director of the Energy Policy Institute at the University of Chicago and Lab co-director. “It can mean the difference between life and death.”