For someone who has put a lot of effort into confounding the stereotype that Green Party members are all beardy, sandal-wearing, lentil-eating (etc. etc., insert your own favourites – the best one directed at me so far is ‘bunny-hugging’ from a caller on Radio 2), it may seem a bit odd that I have decided to give a big plug to National Vegetarian Week.

But no, not odd at all. The theme of this year’s event, run by the Vegetarian Society from this Monday to next Sunday, is how going veggie is good for the planet. And the fact is they are completely and utterly right.

Farmed cows and sheep are responsible for nearly two fifths of the total quantity of methane generated by human activity. As a greenhouse gas, methane trumps carbon dioxide many times over, so the contribution of animal farming to climate change is actually more than our entire transport system. This makes a lot of sense if you think about it. All of us eat things and most of us aren’t vegetarian, but not everyone has a car or a mini-break obsession (in fact only a tiny proportion of us globally have either).

Rearing animals also uses far more water than growing vegetarian food – thousands of litres go into making a kilogram of beef – and it uses up vast amounts of land, providing crops for food for animals for food for us. A madly inefficient way of managing the world’s resources.

What appeals to me most about the environmental argument for cutting down on meat is that it’s not an all or nothing thing. Reducing your carnivorousness is as easy as adding just a couple of new vegetable-based dishes to your repertoire, and every meal without meat helps to cut your carbon footprint. Simply bearing this in mind while you look over a menu is far less daunting than taking a pledge not to ever have a bacon sandwich again.

Nevertheless, I am going to take up the Vegetarian Society’s challenge and be completely veggie for the next week. To be honest, I’ve been a very light consumer of animals for ages – for precisely the environmental reasons listed above – and I already steer well clear of battery eggs and intensively farmed, frightened meat of all kinds.

Recently, I have unintentionally become even more virtuous, since discovering I prefer garlicky tofu to chicken in stir fries and developing a taste for a delicious recipe involving big green lentils mixed up with cabbage and drenched in vinaigrette. This latter fetish has amused my local shopkeeper, who knows all about my political work and chuckles, “Green Party, green lentils” when I go to stock up.

For myself then, with most days going by without meat touching my plate, and with the only flesh I can find in my fridge today a chunk of East European sausage, giving it up completely for a week shouldn’t be too hard. But I’d urge everyone to give it a go. Starting with a week of real vegetarianism is a great excuse to try some new things and start eating a bit more healthily – for yourself and for the planet.