Imagine a better world

Given that humans are here to stay on Earth for some time yet, what can we do to lessen our impact?

The World Without Us

Thomas Dunne Books/Virgin Books: 2007. 288 pp. $24.95 £20.00 0312347294 | ISBN: 0-312-34729-4

Imagining “the world without us” is such a clever idea. It powerfully motivates thinking about what the 6 billion of us do to Earth. It conjures, too, reflections on the sometimes surprising parts of Earth that we have left alone. How these have fared might shape future environmental choices.

There are still places that exist without us, such as the Bialoweiza forest in Poland. Credit: J. KORBEL

The examples in Alan Weisman's The World Without Us are familiar from numerous other books about the planet today. Of course, good science books assemble what is already known to the academic priesthood to make the ideas widely accessible. They strongly influence that priesthood, embarrassed as we often are to admit we found the original literature unintelligible. Great books synthesize facts and ideas onto a sweeping canvas. Sadly, Wiesman's book does not assemble, synthesize, step back from its details to pose larger questions, engage the reader in a debate about the salient features of human impact or present solutions. It has no introductory and final chapters laying out key issues.

The book does come frustratingly close to being more than its collection of set pieces. Chapter one has a photo of the massive trees in Bialoweiza forest, Poland. Many trees get that way — if we allow them to. Without us, one can almost imagine the loud sucking sound of Earth's trees growing to old age, taking back the carbon. Without us, some 15 million square kilometres of former cropland and another 5 million of tropical forest cleared for grazing would re-grow, sucking up roughly 10 gigatonnes of carbon each year for the next 30 years or more. Even ignoring other sinks, including soils, this very rough calculation suggests an immediate, significant reduction of atmospheric carbon, with attendant climate changes. The all too obvious practical answer to Richard Branson's challenge to remove carbon dioxide from the atmosphere is growing trees. Without us, there are lots of places for them to re-grow; even with us, there are too.

Without us, the nitrogen junkies of the global flora would protest the halving of their annual fix. Human chemistry has doubled the availability of fixed nitrogen through fertilizer in the biosphere. Without us, trees would flourish, nitrogen-dependent weeds would not, and most domesticated crop plants would die within the year.

Weisman worries about the bison in Bialoweiza, imprisoned there by its fence. He moves on promptly to discuss how our buildings would decay and how the subways of New York would flood if we were gone, a subject of a morbid fascination, no doubt, to those who enter them daily.

He misses an opportunity in the chapter on “the world before us”. Our nearest relatives remain in this book's conceit. Evolution might not recreate us, but what about an ape with our intelligence? Palaeoanthropologists argue that man is just the forest ape who moved into the savannas in compelling (if often contradictory) creation stories. So, what is to stop a repeat performance? Weisman concludes that the aggressive common chimpanzee (Pan troglodytes) will overwhelm the meek — and much rarer — bonobo (Pan paniscus). Would this prevent a new 'man' from following in our path, or is an aggressive Pan the key step? This is an interesting, but unexplored possibility.

Such debates are fun over morning coffee. Other issues are practical and vital. There are places without us and we could designate more. Some of them are in this book — the demilitarized zone between the two Koreas, the Bialoweiza forest, a few isolated reefs, decreasing areas of rainforest. These examples broach the biggest challenges of this century: can we reverse global carbon emissions, cool off the planet and prevent the irreversible loss of biodiversity?

Weisman discusses how nature returns in our absence. Allowing native trees to recover — the Lorax solution — so that both the trees and their friends will come back is also a good start to solving the biodiversity problem. He also discusses the constraints we have placed on recovery. For example, we have introduced weeds — that is, species that belong in other places. But we have not followed US environmentalist Aldo Leopold's first law of intelligent tinkering: to keep every cog and wheel. Nor have we followed the second law: to keep the instructions. There is no guarantee that even with all the pieces, we would be able to put nature back together again. The book successfully warns us that almost everywhere are human artefacts that will be with us for a long time — plastics, for example — making things ever more complex.

These and many other good leads are in The World Without Us, but their placing is incoherent. There is not going to be an Earth without us. So excluding us from some of it and reducing our impacts elsewhere is an important part of a discussion that this book could do a lot to facilitate. Perhaps the broader vision — the missing introductory and final chapters it so clearly needs — could be added on a related website.

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Pimm, S. Imagine a better world. Nature 448, 135–136 (2007).

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