The best thing that any of us can do for the environment is to adopt a vegetarian diet.
It's also argued that it is inefficient to grow crops to feed to animals to eat their meat, milk, eggs, etc, rather than just grow the crops to feed the people. Greenpeace USA says:
It takes up to 10 pounds of grain to produce just one pound of meat. ... The world’s cattle alone consume a quantity of food equal to the caloric needs of 8.7 billion people — more than the entire human population on Earth.
But I'm not totally convinced. Just east of where I live is Derbyshire, a rocky county of low mountains and fells. It's sheep-rearing country, because nothing else can thrive there. Dry-stone walls separate the fields, not because they look picturesque, but because even hedges won't grow reliably on the thin soil and the wind-blasted hills. If you didn't farm sheep there, you wouldn't farm anything.
In the book The New Complete Guide to Self Sufficiency, John Seymour strongly advocates keeping a cow on any smallholding, even one as small as a single acre, primarily because of its fertility-generating properties (he means dung). Pigs are also prized by smallholders as the rapidest of compost-making systems. You put food scraps, vegetable trimmings, windfall apples and so on in one end of the pig, and within 24 hours fertiliser comes out of the other end. And you get to eat the pig. It's a win-win situation.
Of course, most of the meat you buy in supermarkets isn't produced this way. Too often it is produced intensively. They call them farms, but really they're much more like factories. And they do produce horrendous amounts of pollution, they rely on enormous quantities of grain and soya and water, and the animal welfare is non-existent.
So I'm not asking you to become a vegetarian. I don't think it's necessary, and I don't think you would do it anyway just because I asked you. I'm asking you, this month, to have a vegetarian main meal once a week. Don't give up meat, but do eat less meat. If you know somewhere you can get well-produced meat, perhaps from a farm shop or a farmers market (don't assume all farm shop or farmers market meat is well-produced - talk to the butcher and ask lots of questions) then please use that rather than the supermarket.
I'll be posting lots of simple and tasty vegetarian recipes this month. Please email me your favourite vegetarian main meals. And I'll be talking about the environmental impact and ethics of meat eating. If you're up for the challenge of eating four vegetarian main meals in April, please vote in the poll in the right-hand sidebar.