On the front of a carton of milk from the Portland, Oregon-based brand Neutral, above the brand name, the package has a short message in large print: “This milk fights climate change.” On its website, the company lists the number of pounds of CO2 that were offset to give the milk that tagline-12 pounds, in the case of a carton of organic 2% milk.

The company works with dairies to reduce emissions as much as possible, and then offsets the rest, making each product carbon neutral.

“All in all, dairy accounts for 3% of all global emissions, more than the entire aviation sector, and by working with farmers to reduce emissions, Neutral Foods is addressing one of the largest areas for climate impact,” says Carmichael Roberts, business lead of Breakthrough Energy Ventures’ investment committee.

The company worked with researchers to study the carbon footprint of dairy, from the fertilizer used to grow cattle feed, to the methane in cow burps and manure, to the power used on the farm, delivery trucks, and bottling plants, and even what happens to empty milk cartons.

While some dairies have already taken significant steps to shrink their carbon footprints, most still have ample room to change.

To offset remaining emissions, the brand buys certified offsets from other parts of the dairy industry, including larger dairies that use methane digesters, equipment that turns manure into energy, funding the expansion of digester use on those farms.

The company plans to later sell carbon-neutral versions of other types of food, but wanted to begin with dairy because of its importance in terms of the climate.