Nobel Prize-winning Indian scientist Rajendra Pachauri and musician Sir Paul McCartney have teamed up to urge people to become vegetarian to save the planet from the greenhouse gases created by rearing livestock.

According to a letter sent to The Independent, Dr Pachauri, chairman of the Intergovernmental Panel on Climate Change (IPCC), and McCartney, who are both vegetarians, blame the worsening global warming on a rise in the number of people who eat meat.

They believe that global food shortages are exacerbated by the planting of cereal crops for animal fodder. A mass switch to a more vegetarian diet will, according to them, help the poorest people in the world.

Becoming vegetarian, or at the very least eating less red meat, is the single most effective act anyone can take to lessen greenhouse gas emissions, said Dr Pachauri and McCartney.

As well as producing the greenhouse gas methane, the livestock business uses up increasingly scarce sources of fresh water and increases other forms of pollution through its need for agricultural chemicals, they argue.

Dr Pachauri and McCartney cite a 2006 report by the UN's Food and Agriculture Organization, which stated that livestock are one of the most significant contributors to climate change because 70 per cent of former forests in the Amazon have been turned over to grazing and livestock now use 30 per cent of the world's land surface.