Dozens of new books appear to provide an answer: we can save the world by embracing "better, greener lifestyles". Last week, for example, the Guardian published an extract of the new book by Sheherazade Goldsmith, who is married to the very rich environmentalist Zac, in which she teaches us "to live within nature's limits". It's easy: just make your own bread, butter, cheese, jam, chutneys and pickles, keep a milking cow, a few pigs, goats, geese, ducks, chickens, beehives, gardens and orchards. Well, what are you waiting for?

Her book also contains plenty of useful advice, and she comes across as modest, sincere and well-informed. But of lobbying for political change, there is not a word: you can save the planet in your own kitchen - if you have endless time and plenty of land. When I was reading it on the train, another passenger asked me if he could take a look. He flicked through it for a moment then summed up the problem in seven words. "This is for people who don't work."