See Paul McCartney's Star-Filled 'Meat Free Mondays' Video

The song celebrates the fifth anniversary of the Meat Free Mondays campaign, which urges people to take a day off from eating animals in an effort to help the environment

Paul McCartney has made a music video in support of his family's Meat Free Mondays campaign, which urges people to take a weekly break from eating meat in an effort to help the environment. The song – which dates back to 2009, when the outspoken vegetarian cofounded the effort with his daughters Mary and Stella – lays out all the benefits to slightly changing one's diet, including reducing greenhouse gases and slowing down the polar ice thaw and rising ocean levels. His video features people from all over the world holding up signs with the song's lyrics, including celebrities like Woody Harrelson, Twiggy and actress Joanna Lumley. McCartney makes a wide-smiled appearance at the end.

The former Beatle renewed his Meat Free Mondays campaign last week when he posted a video called "An Urgent Call to Action" to YouTube. In the clip, he asked people to pledge their support to his campaign so he could lobby to bring it more attention. "We'll send all these pledges to the politicians and then they'll do something about it," he said.

McCartney timed both videos to the U.N.'s Climate Summit in New York, which takes place September 23rd. The summit was heralded with what Rolling Stone predicted would be the "biggest climate protest ever." Part of the protest was the People's Climate March, which took place in New York on September 21st and was backed by more than 1,400 organizations, including environmental and labor groups, churches and schools. Ultimately, more than 400,000 protesters showed up to storm the streets of Manhattan.

"This is the most important day yet in the fight against global warming – but it is still just one day in the life of a movement," the march's organizer, Bill McKibben, told Rolling Stone. "We will need to keep growing this fight bigger and stronger, and we will need to do it fast, since that's the speed at which the pace of climatic destruction is accelerating."