Thursday, 29 July 2010

Welcome to the Anthropocene!

My first copy of the Open University's 'Geological Society Journal' hopped through the letter box a few days ago and one paper stood out from the others mainly because of it's authors. Dr Mark Williams and Dr Jan Zalasiewicz from Leicester University are two people I met at last years open day at the university and Jan is the author of a splendid book called 'Earth after Us' that I featured in a blog last year (click here to read). The title of the paper is "Enter the Anthropocene: an Epoch of time characterised by humans".

I've often speculated about the likely legacy we humans will leave for future occupiers of planet earth and whether there will be anything left worth occupying millions of years from now. I have always, perhaps a tad naively, believed that maybe man isn't quite as stupid as I fear and will drag the planet back 'from the brink' eventually. But will we? It seems that many believe the earth's failsafe feedback mechanisms could, quite soon be pushed beyond the point of no return, ultimately leading to the destruction of all life on planet earth, leaving nowt but a seemingly dead mass like Mars! James Lovelock, in his book 'Revenge of Gaia' I think touches on this very possibility if I remember correctly.

Anyway, Zalsiewicz and Wiliams' paper looks at the degree of environmental change brought about by man's activites, takes the idea first proposed by the Nobel Prize winning scientist Paul Crutzen and suggests ideas for formalising a specific epoch of geological time to cover the period of human influence on earth.

But how does one classify it? When did this epoch start? Is there a specific event that says before this event is the holocene and after it is the anthropocene? Well, there are a number of factors that might just leave a signature for future visiting geologists from afar to read. Firstly, the extinction of the large animals or 'megafauna' seemed to coincide with the rise of the human being, e.g the mammoths. However, it is difficult to be specific about the date as they died out in the americas 13,000 years ago, but died out 50,000 years ago in Australia. Some 'megafauna' survive today, e.g. elephants and rhino, but are unlikely to be around for too much longer. So maybe the Anthropocene requires a better means of classification?

The introduction of agriculture may provide a more specific date in order to gauge the start of this new epoch. WThe onset of agricultural practices brought widespread tree felling and planting of food crops which will have completely changed the composition of pollen grain accumulations in sediments worldwide, leaving a clear signature in the future rock record. This process will also have altered the level of carbon dioxide in the atmosphere and this too will be detectable by the future geologist.

Another potential means of dating the onset of the anthropocene could be in reading the signs of mans activities. No previous lifeform on earth has physically changed the outward structure of earth quite like man. Just how detectable the remains of man's handywork will be is difficult to gauge. Huge ancient cities vacated just a thousand years ago are now merely dust and rubble. But surely the vast quantities of brick, steel and concrete that make up our twenty-first century megacities will leave plenty of clues and a good idea of just when man was at his creative (or destructive, depending on your outlook) peak? As for how long the anthropocene will last is also difficult to estimate, but the pessimistic amongst us might suggest the width of this potential epoch might not occupy too much paper on the future geologist's stratigraphic column! 

The slightly depressing thing that came to my thoughts when reading this piece was that we humans and our relatives have only been around for a few hundred thousand years and are already making a good job of orchestrating our own demise. Yet the good ol' dinosaurs were the dominant vertebrate from the Triassic through to the end of the Cretaceous! That's a whopping 160 million years!?! That makes man's tenure seen pretty short term. And we like to think of ourselves as intelligent? Sorry, but making such a 'pig's ear' of everything in such a short (geologically speaking) space of time makes us look pretty dumb! That said, rapid increase followed by sudden extinction is not at all unusual. Let's hope we can turn things around before its too late.

Cheers for now!


1 comment:

  1. Dear Alyn,

    Human are definitely stupid, not intelligent, just look at the oil spill, it lasted so long and, near to the so called world's super power. If the super power is unable to do anything about the oil spill, what about us, in the third world who are also care about this. This might leave a layer of poignant record in the future sedimentary rocks like the KT event...also a sad episode, but the difference is the later being an unaviodable scourg of celestial in nature as opposed to self-induced destruction, human, greedy and hopeless.


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