The world is warming, incomes are rising, and smaller families are living in larger houses in hotter places. One result is a booming market for air conditioning — world sales in 2011 were up 13 percent over 2010, and that growth is expected to accelerate in coming decades.

By my very rough estimate, residential, commercial, and industrial air conditioning worldwide consumes at least one trillion kilowatt-hours of electricity annually. Vehicle air conditioners in the United States alone use 7 to 10 billion gallons of gasoline annually. And thanks largely to demand in warmer regions, it is possible that world consumption of energy for cooling could explode tenfold by 2050, giving climate change an unwelcome dose of extra momentum.