No lesser luminaries than Sir Paul McCartney, Sir Richard Branson, Joanna Lumley and Ricky Gervais are advocating we have Meat Free Mondays to help tackle climate change.

Are they right to do so? Absolutely. But the reality is that we would have to cut down on our meat intake by at least half to see a difference.

The meat and dairy industry is responsible for about 18 per cent of global greenhouse gas emissions. That's more emissions than all the planes, cars, buses and trains on the planet (13 per cent).

These figures are based on the well respected United Nations Food and Agriculture Organisation's report entitled Livestock's Long Shadow.

There are three big reasons for this. The first is called enteric fermentation, colloquially known as belching. Cattle are responsible for 75 per cent of all methane emissions.

The second reason is the emissions from animal manure. But by far the worst problem is the destruction of the South American rainforest to grow soya and cereal crops which act as protein feed for a lot of our livestock.

For that reason, what the animals eat is just as important as what we eat.

That is why Friends of the Earth is launching a new campaign to persuade the Government to act to prevent livestock being fed soya protein feeds.

Currently, the Government uses taxpayers' money to subsidise factory-farmed meat and dairy to the tune of £700m each year. We want that money redirected to sustainable farming systems, supporting small and family farms that benefit rural communities.

Our campaign launch is on Saturday between 10am and 2pm in Exeter High Street, near Boots.

We do not necessarily advocate a total vegetarian diet, as some meat replacement products can be high in carbon, and some naturally grazed meat can be low in carbon. But we do strongly urge people to eat less meat, especially beef.

Maurice Spurway

Co-ordinator, Exeter Friends of the Earth

(by email)