Oh lamb chops, oh pork belly, oh brisket of beef, how numbered are your days! Where will you go to, barbecued ribs, now you have been exiled from this kingdom? Yes, this week, Lord Stern, the author of the Stern Review on the Economics of Climate Change, announced that it is time to address the nation's carnivorous habits. "Meat," he declared, "is a wasteful use of water and creates a lot of greenhouse gases. It puts enormous pressure on the world's resources. A vegetarian diet is better."

For many, the prospect of a life without meat may seem far more desolate than a world without polar ice caps. But the plain fact is that we must reduce the amount of meat and dairy we consume if we are to protect our planet. A kilogram of beef is responsible for more greenhouse gases than a three-hour car journey while leaving all the lights on in your home. Our oceans are overfished and polluted by commercial fish farms. And while you might be a little gloomy about the notion of a lunchtime without a ham sandwich, the message is really quite simple: grow up and stop wrinkling your nose. After all, they are only lentils, and they will not hurt you.

However, the transition to vegetarianism can be daunting. The most sensible approach is to gradually reduce the quantity of meat in your diet. For some people this may mean cutting out red meat, or all meat except fish, or perhaps just cooking a Sunday roast and spreading the meat through the week. At the same time, try to release your white-knuckled grip on the idea that meat makes a meal; in Britain we have become wedded to the image of a meal as a central piece of meat, dressed up with some carbs and vegetables, but there are many other types of cooking, such as Indian, Thai and Japanese, that lend themselves more readily to simple vegetarian cuisine.

When giving up meat, many people are tempted to run straight into the welcoming arms of cheese. This is not a great idea. Dairy farming also has a hugely detrimental effect on the environment (not to mention the fact that not all cheeses are actually vegetarian). Broaden your culinary horizons, get to know tamari and tempeh, soy milk and cashew cheese, enjoy a little experimentation.

If someone replaced my tofu with some tofu-flavoured chicken, I too would be upset. So likewise, it's best not to try directly replacing a meat you love with a vegetarian alternative – a craving for pork chops will never be met by a slab of tempeh, and vice versa. Yes, for some, fakin' bacon and Quorn fillets are a stepping-stone to vegetarianism, but personally I think you'll be disappointed. It is far better to acquaint yourself with the delights of vegetarian cuisine, to understand that in fact the staples of vegetarian diets are not meat substitutes but are simply different foods and you have to learn how to work with them; you don't cook tofu like chicken, just as you don't cook trout like guinea fowl. Give it time and enthusiasm and an open mind.

Five tips for going vegetarian

1 Don't go cold turkey Giving something up in one go rarely works; if you reduce your meat consumption gradually you will be more likely to stick to it.

2 Be sure to get your vitamins Meat is an easy source of iron and B vitamins. Instead, choose green leafy vegetables, seaweeds and use B-rich nutritional yeast (such as Marmite) in sauces.

3 Go easy on the cheese Dairy farming is also environmentally damaging, so investigate vegan cheeses, which are made from soy or nuts.

4 Don't seek out substitutes If you leap straight from chicken breast to Quorn fillets you will be disappointed.

5 Be adventurous Exploring vegetarian cuisine is much like learning how to cook Japanese or real Italian – it's exciting and subtle and takes a little time.