Paul McCartney makes video for Meat-Free Monday campaign

Sir Paul McCartney wants people to avoid eating meat. (Meat Free Mondays)

Sir Paul McCartney wants everyone to make his or her diet animal-free once a week in an effort to slow climate change.

The ex-Beatle, a long-time vegetarian, has recorded a song to help promote a global Meat-Free Mondays campaign, according to Sky News.

He enlisted the help of his famous friends such as Joanna Lumley, Twiggy, Sharleen Spiteri and Woody Harrelson to shoot a video which is a montage of photographs featuring of each of them holding up signs bearing the words of the song.

It is believed that greenhouse gases resulting from livestock production is a major contributor to climate change.  According to the journal Nature Climate Change, greenhouse gases will increase by 80 percent in the years to come as more countries adopt American-style diets, which are more focused on meat and dairy consumption.

In addition to the tune, McCartney released a video message asking for support to his cause by logging into the campaign's website Pledge.meatfreemondays.com ahead of Tuesday's United Nations climate summit in New York City.

"Please do it. We'll send all these pledges to the politicians, and then they'll do something about it, " he says.

More than 843,000 people – including celebs such as Gwyneth Paltrow, Mark Ruffalo, Kevin Spacey and Ricky Gervais – have signed up to the pledge.