This Chart Shows How Your Cheeseburger Is Connected to Climate Change by Matthew Heimer @FortuneMagazine August 23, 2016, 2:43 PM EST E-mail Tweet Facebook Linkedin Share icons When people talk about climate change, they usually discuss the impact of carbon emissions—more specifically, the carbon dioxide that’s produced when we burn gasoline, coal, or other fossil fuels. But methane is also a so-called greenhouse gas—and it’s a big by-product of our food chain. Some of it comes out of the, um, back ends of dairy and beef cattle and other livestock; some of it is emitted when animal waste decomposes. Whatever the source, many environmentalists argue that the world needs to make its food supply more efficient and less meat-dependent in order to curb its methane problem. Two companies on this year’s Fortune Change the World list are attacking the issue from different directions. Novozymes (#9 on the list) nvzmy , a Danish bioengineering company, sells enzymes that make animal feed more digestible, and therefore more efficient. Compass Group (#33) cmpgy , a British institutional food-service company, is reducing the amount of red meat in the millions of meals it serves every day. For more on Change the World list, watch this video: Click here to learn more about these two pioneers and the other 48 companies on this year’s Fortune Change the World list. This chart appears as part of the “Change the World” package in the September 1, 2016 issue of Fortune.