A California startup using rocks to soak up carbon dioxide from the air has teamed up with a Canadian company to mineralize the gas in concrete, a technological tie-up that is a first and they say could provide a model for fighting climate change globally.

U.N. scientists concluded that removing billions of tons of carbon dioxide already in the atmosphere, in addition to cutting current emissions, will be necessary to limit climate change. To do that, two things are needed: first, capturing carbon dioxide with nature or technology, and second, locking it up for centuries.