Michelle Rafferty, Publicity Assistant
Jan Zalasiewicz is a field geologist, paleontologist and stratigrapher, as well as lecturer of geology and Earth history at the University of Leicester in Leicester, England. He researches fossil ecosystems and environments across over half a billion years of geological time, and has published over a hundred papers in scientific journals. His latest book The Earth After Us: What Legacy Will Humans Leave in Rock? published this fall in paperback. In his Countdown to Copenhagen post, he talks about Anthropocene, the new human dominated epoch we live in, and whether our future legacy will look more like an apocalyptic science fiction novel or a modest geological footprint.
For the rest of the Countdown to Copenhagen posts, click here.
It seems like science-fiction. The Earth will, in a few short centuries – perhaps even decades – go back to the kind of world in which the dinosaurs lived. Ice caps will collapse, oceans will acidify, coral reefs will perish, coastlines will drown. Millions of species will go extinct. And we humans – who set all these events in train – will be in big, big trouble. As science-fiction, indeed, it may be no easier to accept such an idea. Imagine if Terry Pratchett trashed the Discworld, drowned Ankh-Morpork – for ever? His readers wouldn’t stand for it.
Yet this scenario on our one and only Earth seems, on the evidence to hand, more likely than not. Such changes are not certain (perhaps, out there, there is the ecological equivalent of the cavalry over the hill, riding down to rescue us all). But these global changes are not just possible – they are probable. And their scale is not diminished by comparison with the great upheavals of the Earth’s multi-billion-year geological history. Rather, they are made to seem more stark by that comparison.
The enormous canvas of the Earth’s past shows drama, to be sure – the crazy climate switchbacks of the last million years, for instance. But it also shows long episodes of calm and stability. The most recent of these has been the last ten thousand years – our current epoch, the Holocene – since the most recent of the Earth’s glaciations receded. With both temperature and sea level holding remarkably steady, it’s no coincidence that human civilization has flowered over this time. But now, our civilisation has, over two centuries, poured hundreds of billions of tons of carbon into the atmosphere, taking CO2 levels higher than for millions of years. We are near – or perhaps already past – a tipping point, into a new climate regime.
But it is not just climate change, as immense and far-reaching a change as that is. As cities and farmland replace what was once forest and savannah, the Earth’s animals and plants are under siege as rarely before. Extinction rates are now likely somewhere between a hundred and a thousand times higher than is usual. Since we’ve discovered only a tenth or so of the species on Earth so far, it’s certain that many species will become extinct even before they are discovered and named (it makes no difference to those species of course, but for some reason I find that particularly poignant). The seas are no more of a haven, caught between over-fishing, with stocks of edible fish plummeting, and the chemical changes, as that extra carbon dioxide dissolves into ocean water and acidifies it. The Earth has endured five major mass extinction events since multicellular organisms emerged; it seems probable that we are on the verge of a sixth.
This is why colleagues and I are studying the concept of the Anthropocene – the term, coined by Nobel Prize-winning atmospheric chemist Paul Crutzen, to signify the new, human-dominated epoch that we live in. It is not just a vivid metaphor of human impact on the planet. It is a means to soberly, carefully, quantitatively put together the many and disparate changes now taking place. We need to evaluate these changes against their ultimate context – the Earth’s deep history. That almost unimaginably long history is preserved in strata, which geologists are becoming increasing adept at forensically analysing, and reading the messages of past climate, sea level and biodiversity that they contain. The interim report is that what we are doing today is big – and will likely become bigger, before we are through.
Looked at from the vantage point of, say, a hundred million years in the future, our very personal, direct legacy might not amount to much: the crushed and petrified remains of the basements and foundations of one or two towns or cities, perhaps, converted into tomorrow’s strata (though more cities will lie deeply buried). But our wider footprint may well appear as an infinitesimally thin layer in which the world changed, and in which nothing was the same again. It may be as sharp and as striking as the stratal layer that marks the death of the dinosaurs, at the end of the Cretaceous Period. We study this thin end-Cretaceous layer avidly today, ever fascinated, still puzzled. Our very own Anthropocene boundary layer may, in the far future, be quite as dramatic – and, as much of a puzzle to whoever or whatever may, in that future, excavate our remains.
Such study is more than academic. It is – must be – aimed at lessening the very phenomenon that we study. For the greater the scale and geological reach of the Anthropocene, the more imperilled will be the lives of our children and grandchildren. That is why, say, the current negotiations prior to the Copenhagen climate summit, and the various treaties and agreements aimed at protecting what is left of the rainforests and coral reefs, are so crucially, vitally important. They represent the hope that humans can act together to keep their one and only world habitable.
It is too late to render our presence invisible to far future explorers of the planet. But it is not too late to make our future geological footprint a modest one. For that we need to take the long view, and work towards it. Science-fiction disasters are all very well to read about – but we wouldn’t want to live through one. Keep this world as it is – more or less – and Ankh-Morpork will look after itself, for sure.