The Meaning of the 21st Century, by James Martin

It's hard to know what message to take away from this book. On balance, it seems to be "we're all doomed... unless". The question is, how seriously should we take the "unless"? James Martin's doom is familiar enough - population growth, climate change, energy crises, water shortages, terrorism - but presented with panache by the author of The Wired Society. The style may grate a little on this side of the Atlantic, but if you can live with such turns of phrase as "9/11 changed the lens of world affairs" there is a lot to be gleaned painlessly here. I like the image of a convoy of water trucks 300,000 miles long, farther than the distance from Earth to Moon, carrying the amount used by humankind every day over and above that replenished by rain. The insanity of allowing people to drill private boreholes for "free" water (further depleting already underground sources) at a time of shortages is brought home more clearly here than anywhere I have seen.

The trouble is, although Martin is always clear and convincing, in a few places where I have some knowledge he is also wrong. For example, he sayys that "the Sun is slightly hotter than usual". He doesn't say by what timescale he is defining "usual", nor what period is covered by "is". Perhaps he means the Sun is slightly hotter now than in the 17th century; but which state, if either, is "usual"? And his discussion of how hurricanes happen is woefully misleading.

So I would not encourage anybody to take everything at face value, although I have no argument with his claim that "the worst scenario... could be that envisaged by James Lovelock - a planet with damaged control mechanisms and positive feedback" that could "sustain a population that is only a fraction of today's". Martin's contention is that many different problems are reaching crisis point together in the middle decades of the 21st century, like a mighty river squeezed between the walls of a narrow canyon. But he also sees the possibility of a glorious future if we get swept through the canyon and survive to enjoy the ride through the broad lowlands. He lists 17 interlinked challenges that constitute "the 21st-century transition", and goes on, unlike other authors, to offer solutions for all of them.

Many read like science fiction - but then a description of the world of 2006 would have read like science fiction 40 years ago. But Martin is right to remind us that disaster can be staved off if we have the political will. For example, "a war-footing race to transform the oil, coal and car industries may be triggered by extreme climate change and Category 7 hurricanes raging across Florida".

He is also impressed by the continuing growth in computer power, which he sees leading to a "singularity" (essentially, a computer much more intelligent than we are) by the middle of the present century. I remember reading something similar in the mid-1950s, predicting similar "singularities" leading to a paradise on Earth by the year 2000.

Full marks to Martin for airing these possibilities, in what is definitely a "must read" book; but the combination of political, social and religious reformation needed to take advantage of the technological possibilities is unlikely. As he says, much of what needs to be done already simply is not happening, and there is a huge disparity between the right thing to do and what is most likely to happen. I'm with Lovelock on this: a thriving human civilisation in tune with its environment may emerge on the other side of that canyon, but its population is likely to be no more than a quarter of the present one. Unless? Forget it.

John Gribbin's 'Science: a history' is published by Penguin