"We want to be responsible operators and buyers," says Max Verstraete, vice president of corporate responsibility for Hilton. The hospitality company, which has 14 brands covering more than 5,000 properties in 104 countries and territories, buys a lot of products. "Whether it’s furniture or ketchup bottles for room service trays, TVs, electronics — pretty much anything you can think of — we’re probably buying," he says.

Fuel cell cars and trucks are a tiny piece of the U.S. clean vehicle market, due in no small part to the limited number of hydrogen fuel stations in California, one of the few places they’re sold. To help fix that Toyota is building a first-of-its-kind refinery to make large quantities of the zero-emission fuel from a dirty source: cow manure.

More of the world’s biggest corporations are taking the fight against climate change into their own hands, aiming to cut their energy costs, pre-empt regulation or burnish their reputations with investors and customers.

Twenty-five years ago this month the Union of Concerned Scientists published what they hoped would be a game-changing wake-up call to the world.