My actual air conditioner, last seen in my rant in its defense.

The Guardian has an interesting look at the growth in air conditioning usage both within the United States and internationally.

[W]orld 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.

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The United States has long consumed more energy each year for air conditioning than the rest of the world combined. In fact, we use more electricity for cooling than the entire continent of Africa, home to a billion people, consumes for all purposes. Between 1993 and 2005, with summers growing hotter and homes larger, energy consumed by residential air conditioning in the U.S. doubled, and it leaped another 20 percent by 2010. The climate impact of air conditioning our buildings and vehicles is now that of almost half a billion metric tons of carbon dioxide per year.

If the estimates made by the author (Stan Cook, who also writes for Yale’s Environment 360) are correct, car air conditioning accounts for between 5 and 7 percent of the nation’s entire 2011 gasoline usage. (The Energy Information Administration has a somewhat lower estimation of the amount of electricity spent on cooling — some 479 billion kilowatt-hours — though the excludes manufacturing.)

While we’re currently the world leaders in air conditioning use, that’s expected to change.

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China is already sprinting forward and is expected to surpass the United States as the world’s biggest user of electricity for air conditioning by 2020. Consider this: The number of U.S. homes equipped with air conditioning rose from 64 to 100 million between 1993 and 2009, whereas 50 million air-conditioning units were sold in China in 2010 alone. And it is projected that the number of air-conditioned vehicles in China will reach 100 million in 2015, having more than doubled in just five years.

As urban China, Japan, and South Korea approach the air-conditioning saturation point, the greatest demand growth in the post-2020 world is expected to occur elsewhere, most prominently in South and Southeast Asia. India will predominate — already, about 40 percent of all electricity consumption in the city of Mumbai goes for air conditioning. The Middle East is already heavily climate-controlled, but growth is expected to continue there as well. Within 15 years, Saudi Arabia could actually be consuming more oil than it exports, due largely to air conditioning. And with summers warming, the United States and Mexico will continue increasing their heavy consumption of cool.

Good thing we’re not expecting average temperatures to increase any time soon!

There’s a sliver of silver lining. A recent study by the International Energy Agency suggested an alternative system that could substantially reduce carbon output: solar. Yes, even for cooling.

Almost a sixth of the world’s low-temperature heating and cooling energy could come from solar power by the middle of the century, say energy experts.

The move would stop around 800 megatonnes of carbon dioxide from entering the atmosphere each year, says the International Energy Agency (IEA) – more than 1.5 times the annual emission in the UK. …

Thermal cooling technology powered by the sun to cool air can also help reduce the reliance on the electric grid by replacing electric air conditioners.

The key phrase above is “low-temperature.” Thermal cooling isn’t going turn Qatar into a temperate paradise, but it can provide relief in regions with less dramatic extremes.

Oh, and in cars? Turns out you can roll down the windows. Gristmill: At your service.