Can mailing your kitchen scraps to this startup tackle climate change?

The numbers on food waste are staggering. Globally, about a third of the world’s food production is lost or wasted — roughly 1.3 billion tons each year — and most of it ends up rotting in landfills leaking methane, a greenhouse gas 80 times more potent than carbon dioxide when it first enters the atmosphere.

One way to tackle those problems is to reuse that food waste, turning it into more food. It’s...