A 板块｜空调从舒适设备变成救命设施

As extreme heat breaks tempers and electricity grids, fights over AC—or the energy that powers cooling tech—are threatening to break politics. It is a decidedly modern problem: AC hardly existed even in America before 1960; now climate change has made it a near-absolute must in much of the world. In November the COP30 climate summit, held in Belém, Brazil, declared cooling technologies like air-conditioning to be “essential infrastructure” like water, energy and sanitation.

Of all extreme weather, high temperatures are overwhelmingly the most deadly. Between 2000 and 2019 an estimated 489,000 people died of heat each year, according to modelling published in the Lancet, a medical journal. AC has proved a strikingly effective response. A separate study in the Lancet estimates that by the early 2020s AC was averting around 190,000 deaths each year in people aged 65 or older. In America researchers at the National Bureau of Economic Research reckon that residential AC was responsible for a roughly 75% decline over the 20th century in the risk of dying on a very hot day, defined as above 27°C on average. Almost all of that decline came after 1960, when American households began to adopt AC.

B 板块｜付不起制冷，发展差距会自己扩大

In poor countries, most of which are in hot climates, the politics of AC will get a lot stickier. Both their populations and their governments face formidable budget constraints when adopting cooling technology: AC units are expensive, energy is often expensive, and upgrading grids is expensive. Though more than 80% of the world's population regularly encounter the kind of heat for which cooling is needed, just 40% of those people are able to get AC.

Countries that cannot afford to invest in grids, and in AC, risk entering a self-reinforcing spiral. In 2009 Lee Kuan Yew, Singapore's founding father, famously cited AC as one of the most influential inventions in history for “making development possible in the tropics”. Lee's city-state became rich for a host of other reasons, but AC helped things along. Without AC many other hot countries will fall further behind. In eastern and southern Africa, UNICEF reckons that over-hot classrooms (along with other climate shocks) have interrupted schooling for 130m children. The International Labour Organisation estimates that by 2030 heat stress will erase 2.2% of the world's working hours—the equivalent of 80m full-time jobs—with the losses concentrated among agricultural workers in South Asia and west Africa.