Roy Williams | June 28, 2008

The World Without Us

By Alan Weisman

Virgin Books, 324pp, $27.95

FOR a book that imagines the end of the human species, The World Without Us is a remarkably enjoyable read. US journalist Alan Weisman serves up a luscious smorgasbord of facts and speculation about the Earth. The ecological message is deeply serious, but Weisman's tone is light and his prose isgorgeous.

He asks us to imagine "a world from which we all suddenly vanished", but not as a result of a planetary catastrophe such as nuclear holocaust or an asteroid collision. The Earth would be left just as it is today. The only difference is that humans would no longer be here to exercise dominion over it.

Such a doomsday scenario may not be far-fetched. One possibility is plague: as Weisman points out, if AIDs or a strain of the deadly Ebola virus became airborne, people might well be defenceless.

Likelier, however, is that hubris and technology could bring us down. There are several precedents. In the 8th century, the high Mayan civilisation of central America vanished suddenly after 1600 years of peaceful and flourishing coexistence, "devoured by their own greed", as he puts it. One expert quoted by Weisman observes: "The balance between ecology and society is exquisitely delicate. If something throws that off, it can all end."

So, if it all ended in 2008, what would be the human legacy? What would be our record?

On the criteria of destructive short-term influence on the natural environment, we would score highly. Once Homo sapiens ventured beyond Africa and Asia about 50,000 years ago, "all hell broke loose". The key turning point may have been the invention of agriculture, about 11,000 years ago in the Middle East.

There are now but a few places on Earth that remain entirely pristine. Weisman describes the Gombe Stream in Tanzania and the Chambura Gorge in Uganda, remnants of the region from which our species first emerged. Others are Kingman Reef near Christmas Island, and the Bialowieza Puszcza on the border of Poland and Belarus, a sliver of the original forest that once covered the whole of Europe.

These glimpses into the past highlight the dire consequences for flora and fauna of our short terrestrial reign. As recently as 6000 years ago, the Sahara Desert was verdant grassland and the North American continent was home to many more species of megafauna (elephants, hippos and the like) than Africa is today. Weisman provides many other startling examples of our handiwork.

Each year, we cause the death of many billions of birds (they fly into towers, power lines, cars and glass windows) and 100 million sharks. Sharks kill about 15 people a year.

Perhaps most astoundingly, humans are responsible for a dense floating garbage patch in the north Pacific ocean covering 26millionsqkm: a ghastly gyre of "cups, bottle caps, tangles of fish netting and monofilament line, bits of polystyrene packaging, six-pack rings, spent balloons, filmy scraps of sandwich wrap, and limp plastic bags that (defy) counting". There are six others not much smaller.

Our impact, then, has been considerable. How long after our demise would it take for nature to fight back?

In many respects, Weisman suggests, not long at all. Within weeks, he says, our towns and cities would begin slowly to disintegrate as rains fall, fires burn and vegetation sprouts from every cranny. Within decades, most tunnels and subways would be flooded and roads overgrown; some bridges and buildings would crumble and collapse. The Panama Canal -- in Weisman's opinion, "the most stunning engineering feat in human history" -- would close within 20 years, reuniting theAmericas.

Natural ecosystems would regenerate. As Weisman shows, there are small-scale modern precedents: the demilitarised zone on the border of North and South Korea, uninhabited since 1953, and the Varosha resort area inCyprus, abandoned to civil war in 1974, havebeen reclaimed by nature with amazingrapidity.

Some of our nastier by-products would endure, however: billions of rubber car tyres, feral cats, open-cut coalmines, transplanted Australian eucalypt trees and plastic products of all kinds, with which "organisms will be dealing indefinitely". We would also bequeath huge quantities of lead and carbon dioxide in the atmosphere and the soil.

According to Weisman, perhaps the two gravest environmental dangers would be those posed by unmanned petrochemical plants in the Middle East and Texas, and by the 441 nuclear power stations dotted across the globe. Left untended, the former will erupt one day in colossal firestorms; the latter house large amounts of toxic waste that is stored in water tanks. Eventually those deadly substances will be exposed to the air and the radioactivity that is released will "last into geological time".

Theological questions aside, will humans leave any worthwhile legacies? Things that will survive the ravages of time and nature and that, in the far distant future, may be of interest to other sentient beings?

Weisman suggests a few: ceramic art and bronze sculpture; the presidential statues carved in granite on Mt Rushmore in South Dakota; certain underground and undersea structures, such as the Moscow and Ankara subways and the $21 billion Folkestone to Calais "Chunnel", which may last millions of years. But we will leave only one immortal sign, the radio messages that have been beamed into outer space.

Roy Williams is a Sydney writer. His first book, God, Actually, was published this month.

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