The business of cooling the planet

Climate scientists and their billionaire backers, like Bill Gates, are trying to turn down the global thermostat – and make money doing it.

Lately another approach to cooling the planet, with far fewer risks, has attracted the attention of a handful of prominent scientists and several wealthy investors, Gates among them. It’s a straightforward, albeit audacious, way to deal with the threat of global warming: Build many thousands of big machines to remove carbon dioxide from the air.