Paul McCartney, the ex-Beatle, is calling for meat-free Mondays, according to The new campaign, supported by other celebrities including Woody Harrelson, Sheryl Crow, Kevin Spacey and Alec Baldwin, calls for participants to observe one meat-free day a week. Supporters say it will help slow climate change.

The group says that, according to United Nations Food and Agriculture Organization data, livestock production is responsible for more greenhouse gas emissions globally than transportation.

"Having one designated meat-free day a week is actually a meaningful change that everyone can make, that goes to the heart of several important political, environmental and ethical issues all at once," McCartney said. "It not only addresses pollution, but better health, the ethical treatment of animals, global hunger and community and political activism."

For more information, see the group’s Web site, that features vegetarian recipes.