Two billion people worldwide do their cooking on open fires, producing sooty pollution that shortens millions of lives and exacerbates global warming. If widely adopted, a new generation of inexpensive, durable cook stoves could go a long way toward alleviating this problem.

With a single, concerted initiative, says Lakshman Guruswami, the world could save millions of people in poor nations from respiratory ailments and early death, while dealing a big blow to global warming — and all at a surprisingly small cost.