6 billion: That’s how many air conditioners we can expect to see in use globally by 2050, if current trends persist, according to a report by the International Energy Agency. That would be three times the current number, with two-thirds of the world’s households owning an air-conditioner. According to MIT Technology Review, all of this cool air would require 6,200 terawatt-hours of energy, or nearly a quarter of the world’s total electricity consumption today.

Unlike computers, electricvehicles, or meatless burgers, air conditioning has seen only marginal technological improvements since it was introduced nearly a century ago. As the world gets hotter, the demand for cooling our indoor spaces is only increasing, and the emissions created by the energy demands of air conditioning and leaks of refrigerants, which are greenhouse gases, will in turn continue to make the outdoors even hotter. (So far, 2020 has been the second-hottest year on record. Clearly nature is not healing fast enough.)

Better insulation, alternative refrigerants, and other cooling solutions like green roofs can help lessen the climate impact of air conditioning, but the fundamental technology needs a major overhaul. Some startups are working on it: Transaera, founded by an MIT professor, is using new materials to fix conventional air conditioners’ inefficient approach to dealing with humidity, and California-based Skycool is developing high-tech mirrors that would reflect heat into space. Companies in this space raised $350 million last year and $200 million so far this year. If that sounds like a lot, consider that eyeglasses maker Warby Parker just raised a $245 million round of funding.

What’s really cool: An air conditioner that doesn’t heat up the rest of the planet.