Uneaten food often ends up in the trash, but Olio, an app created in 2015 by English entrepreneurs Tessa Clarke and Saasha Celestial-One, allows people with extra food to post a picture online. Anyone that wants the food can respond and pick it up as a gift. There is no money exchanged, and no swapping or bartering. Almost 3.5 million people use Olio in 50 countries. The app claims to have prevented “3,775 tonnes of CO2 emissions from entering the atmosphere and eliminating 12,171,045 car miles from the road.”

Nonprofit Project Drawdown notes, “Almost 1.4 billion hectares of land; close to 30 percent of the world’s agricultural land, is dedicated to producing food that is never eaten; and the carbon footprint of food wastage makes it the third emitter of CO2 after the U.S. and China, according to the UN Food and Agriculture Organization. Reducing food waste is one of the most effective ways of tackling the global climate crisis.”