Refrigerators use compressors, condensers, and coils filled with volatile compounds to transfer heat from inside to outside; this same innovation made air-conditioning possible. When I was born, in 1955, air-conditioners in houses (and cars) were rare; today, in almost all of the United States, they’re close to universal. My mother’s father stayed semi-comfortable during Kansas City summers in the thirties and forties by moving a bed into his screened porch and wearing seersucker suits to work. Now it’s possible to pass entire days without encountering air that hasn’t been artificially cooled—and, once you get used to cooled air, its absence can feel unendurable. (In 2011, a retired Army general estimated that the Defense Department was spending a little over twenty billion dollars a year to provide air-conditioning for U.S. forces in Iraq and Afghanistan.)
The use of cooling technology is growing worldwide. China now accounts for close to half of global air-conditioner purchases and roughly three-quarters of global production; in Dubai, where life during much of the year would be next to impossible without air-conditioning, hotel swimming pools are chilled. According to a report published in 2018 by the International Energy Agency, refrigeration in 2016 accounted for about six per cent of the world’s energy consumption, and space cooling accounted for about eight per cent. In the same report, the I.E.A. predicted that worldwide energy use by air-conditioners would triple by 2050, “requiring new electricity capacity the equivalent to the combined electricity capacity of the United States, the E.U. and Japan today.” Energy use by refrigerators is on a similar upward path.
Much of the world’s recent growth in cooling capability has been an adaptive response to global warming. The problem is self-perpetuating, because the electricity that refrigerators and air-conditioners run on is mostly generated by burning fossil fuels. There are other climate impacts. Hydrofluorocarbons—which, for decades, have been the volatile compounds circulating inside most new cooling equipment—were widely adopted as refrigerants because they don’t have the same destructive effect on the Earth’s ozone layer as their immediate predecessors, chlorofluorocarbons. But hydrofluorocarbons are greenhouse gases with hundreds or thousands of times the warming potential of carbon dioxide. Last year, the Environmental Protection Agency adopted a rule phasing down their production and use in the United States by eighty-five per cent over the next fifteen years. But vast quantities are still being manufactured. Leakage is a common problem, and not only when old refrigerators and air-conditioners end up at the dump.
The most widely embraced strategy for slowing the warming caused by cooling technology is to increase the energy efficiency of new refrigerators and air-conditioners. In a 2011 report, the U.S. Department of Energy estimated that its new efficiency standards for refrigerators (which went into effect in 2014 and are currently being updated) would “save the nation almost four and a half quadrillion BTUs over 30 years. That’s three times more than the total energy currently used by all refrigeration products in U.S. homes annually. It’s also the equivalent amount of energy savings that could be used to power a third of Africa for an entire year.” The I.E.A., in its 2018 report, argued that, through “stringent minimum energy performance standards and other measures such as labelling, the average energy efficiency of the stock of ACs worldwide could more than double between now and 2050.” Implementing those changes, it said, would significantly reduce the need for new electricity infrastructure, flattening the curve of future energy demand.