The decision was driven by sustainability reasons, as well as the publisher’s push to increase programmatic sales across the U.S., U.K. and Australian, said Sara Badler, chief advertising officer, North America, The Guardian.

“The Trade Desk’s sustainability efforts promoting the use of open internet exchanges reduces the carbon footprint associated with digital advertising, which is key to our mission and aligned with our values,” she said in a statement. The Guardian publishes a new piece about the environment every three hours, equivalent to more than 3,000 pieces of climate-related stories every year, per Badler.

For The Guardian, joining OpenPath makes sense as a way to route more ad income at a relatively high price and low take rate.