Denis Hayes recently dropped by the Grist office to talk about his new book, Cowed: The Hidden Impact of 93 Million Cows on America’s Health, Economy, Politics, Culture, and Environment, coauthored with Gail Boyer Hayes (and reviewed here). Naturally, we took him to our building’s service elevator and asked him to give his elevator pitch for the book. Watch the video above.

In addition to being a bovine expert, Hayes is a longtime environmental leader and activist and the force behind the newly built Bullitt Center in Seattle, heralded as the greenest office building in the world.