As record-breaking heat waves baked Californians last month, the collective strain of millions of air conditioners forced the state’s grid operators to plunge hundreds of thousands of households into darkness.
The rolling blackouts offered just a small hint of what’s likely to come in California and far beyond. Growing populations, rising incomes, increasing urbanization, and climbing summer temperatures could triple the number of AC units installed worldwide by midcentury, pushing the total toward 6 billion, according to the International Energy Agency’s Future of Cooling report.
Indeed, air conditioning represents one of the most insidious challenges of climate change, and one of the most difficult technological problems to fix. The more the world warms, the more we’ll need cooling—not merely for comfort, but for health and survival in large parts of the world.
But air conditioners themselves produce enough heat to measurably boost urban temperatures, and they leak out highly potent