Paul McCartney believes that livestock are responsible for a large percentage of global warming. The Beatles legend - who is vegetarian - has written a letter to the Conference of the Parties (COP) climate change conference in Doha urging for the Meat Free Monday campaign to be adopted in a bid to slow down the apparent damage done by the ever-growing meat industry.

In the letter to conference leaders Ms. Christiana Figueres, Executive Secretary of the UNFCCC, and Mr H.E. Abdullah bin Hamad Al-Attiyah, President-Designate for COP 18, he wrote, "Although more and more evidence is coming to light showing how the growth of the global meat industry is having alarming environmental consequences, the impact of the livestock sector on global warming does not as yet seem to have been acknowledged by the Conference of the Parties (COP). I therefore call upon you to bring this issue to the attention of the conference and encourage the adoption of policy and individual actions, such as a weekly meat-free day."

The "Hey Jude" hitmaker has also asked for additional food criteria to be introduced in sustainability guidelines in order to acknowledge the connection between climate change and meat production. The Meat Free Monday campaign urges people to go without animal products one day a week, with the initiative active in 22 countries.