Post-human Earth: How the planet will recover from us
30 September 2009 by Bob Holmes
WHEN Nobel prize-winning atmospheric chemist Paul Crutzen coined the word Anthropocene around 10 years ago, he gave birth to a powerful idea: that human activity is now affecting the Earth so profoundly that we are entering a new geological epoch.
The Anthropocene has yet to be accepted as a geological time period, but if it is, it may turn out to be the shortest - and the last. It is not hard to imagine the epoch ending just a few hundred years after it started, in an orgy of global warming and overconsumption.
Let's suppose that happens. Humanity's ever-expanding footprint on the natural world leads, in two or three hundred years, to ecological collapse and a mass extinction. Without fossil fuels to support agriculture, humanity would be in trouble. "A lot of things have to die, and a lot of those things are going to be people," says Tony Barnosky, a palaeontologist at the University of California, Berkeley. In this most pessimistic of scenarios, society would collapse, leaving just a few hundred thousand eking out a meagre existence in a new Stone Age.
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That's why climatologists are looking with increasing interest at a time 55 million years ago called the Palaeocene-Eocene thermal maximum, when temperatures rose by up to 9 °C in a few thousand years - roughly equivalent to the direst forecasts for present-day warming.
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This extra nudge could conceivably tip the Earth out of its present cycle of glacials and interglacials and return it to an older, warmer state. "The Earth was ice-free for many millions of years. The current ice ages started only about 35 million years ago, so we might kick ourselves out of that," says Pieter Tans, an atmospheric scientist at the US National Oceanic and Atmospheric Administration in Boulder, Colorado. Even so, the newly ice-free world would merely be reverting to a familiar state. On this reading of the evidence, even the most drastic climate catastrophe would have little chance of pushing the Earth's physical systems into uncharted territory.
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Eventually, though, evolution wins the day, and after a few tens of millions of years biodiversity rebounds. Sometimes, as after the Ordovician mass extinction 440 million years ago, the new regime looks a lot like the old one. But more often a new world emerges. "You're not re-establishing the old chessboard, you're designing a whole new game," says Erwin.
Now, if you believe in billions of years of evolution, then why panic about "global climate change" when the Earth has done it all before? And if you don't, then why panic about "global climate change" when God is in control? Either way, I just don't get the "need" to force every family to pay something like $5000 a year more for energy...(except, of course, for those like Al Gore that stand to make million$$ on it.)
