This self-styled handbook for environmentally aware living is a mixed bag. Although it purports to be a practical how-to manual, it's actually a collection of notes and essays that point readers to more detailed sources of information elsewhere. Its subject matter, ranging from climate change to sustainable agriculture and social justice, is broad, and those seeking detailed science will be disappointed. But as a primer for the challenges facing the environment - and the strategies being devised to deal with them - it's an enlightening read.

World Changing, which runs to a mammoth 596 pages, is divided into seven sprawling sections covering such topics as Planet, Shelter, Politics and Cities. Each has an introduction, followed by numerous short articles by various of writers. The idea is to cover anything and everything that relates to the state of the planet. Global warming and green energy rightly get a lot of space, as do green shopping and eco-friendly urban planning. Capsule bibliographies and web addresses direct the reader to more substantial works.

Perhaps the best thing about World Changing is that it's realistic. The authors realise that few people are going to turn their lives upside down to save the planet. So they take a 'do what you can' approach. Few home-owners will want to go to the trouble of bolting a solar panel to their roof to generate electricity, for instance. But many power companies offer a green energy alternative that can be obtained just by filling out a form.

The book gives ideas on how to gently adapt one's life for the better. It works on the principle that, if everyone makes small changes, they add up to big ones.

There are lots of surprises in store, even for those who follow environmental issues. Think that the best way to save the planet is to live in the country, side-by-side with nature? Wrong. Cities, when properly planned, are good solutions. Well-planned urban centres use less energy than non-urban ones, and their inhabitants travel smaller distances, minimising exhaust pollution. Suburbia is the worst offender - it disturbs nature with its sprawl, increases car mileage and is energy inefficient. Well-designed skyscrapers may be the most efficient and cleanest living structures of all.

A section called Stuff hits close to home, attacking the root of many environmental problems. Pollution is caused mainly by our consumerist lifestyles, it says. Each time we buy more 'stuff', we become part of a chain that uses huge amounts of energy. When we throw our stuff away, it ends up lingering in toxic landfills for years. Computers and mobile phones, with their toxic nickel-cadmium batteries, are particularly bad offenders. But the authors know we're not going to give up our consumerist lifestyles. So they simply ask that we buy a bit less, and try to buy energy efficient, bio-degradable goods if possible.

World Changing could have been stronger, and the authors rarely cite the sources for the data that underpin their arguments. Notes quoting papers and scientific studies would certainly have provided extra weight. They also avoid discussing the well-known negative effects of some of the proposals. Bio-fuel, which is widely touted as a replacement for petrol, can be ecologically devastating, with forests being cleared to grow the crops that produce it, for instance. These problems will disappear as science progresses. But the authors should have mentioned them.

Still, World Changing's laid-back style and chilled-out Californian optimism make it an easy and enjoyable way to learn the basics about a multitude of pressing issues.