redefining geological history

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Human activity defines new epoch: scientists

 

Welcome to the 'Anthropocene' period of pollution, technology

 

 

 

Randy Boswell

 

The Ottawa Citizen

 

 

 

Wednesday, January 23, 2008

 

 

 

The world of geology is about to be rocked by a controversial bid to reclassify

the present era in planetary history as one in which human activities -- not

natural processes -- are the definitive force shaping the top layer of the

Earth.

 

It will come as a surprise to most non-experts, but just as we are living in the

21st century according to the calendar, we are creatures of what's called the

Holocene in geological time.

 

And it's been that way, according to scientists, for about 11,700 years -- a

discernible boundary in the Earth's history that is marked, among other ways, by

evidence of meltwater lakes and gravel ridges left across the Canadian landscape

when the glaciers retreated at the end of the last ice age.

 

All of recorded human history has taken place within the Holocene, which

textbooks and encyclopedias explain is still unfolding today.

 

But now, a distinguished group of British geologists has provocatively proposed

that the Holocene is over and that we have entered a new geological era -- the

Anthropocene -- in which humans have left such a distinctive footprint on the

Earth's surface through carbon pollution, nuclear fallout, urbanization and

other traces of our immense technological power that it should be officially

recognized by international scientific bodies as " a formal epoch. "

 

" Since the start of the Industrial Revolution, Earth has endured changes

sufficient to leave a global stratigraphic signature distinct from that of the

Holocene ... encompassing novel biotic, sedimentary and geochemical change, " the

scientists state in February's cover story of GSA Today, a flagship publication

of the Geological Society of America.

 

" These changes, although likely only in their initial phases, are sufficiently

distinct and robustly established for suggestions of a Holocene-Anthropocene

boundary in the recent historical past to be geologically reasonable. "

 

The scientists insist they are not simply performing a political stunt to

bolster arguments for the rapid reduction in greenhouse gases to avert

cataclysmic climate change.

 

They say proof of humanity's impact on the environment is now so great that --

in keeping with scholarly tradition -- the International Commission on

Stratigraphy and its parent agency, the International Union of Geological

Sciences, should declare a new boundary between the Holocene and the

Anthropocene.

 

" We are now living in a new time period when the human modification of the

system is so great, we need some way of recognizing that, " Mark Williams, a

University of Leicester paleobiologist and co-author of the article, said

yesterday.

 

He said the Anthropocene could be pegged as beginning with the Industrial

Revolution about 200 years ago, " when human industrial processes started to

transform the planet on a colossal scale. "

 

He said distinctive increases in carbon dioxide deposits in Arctic and Antarctic

ice cores or traces of radioactivity from nuclear weapons tests beginning in the

mid-20th century -- and which can be found all over the world -- could be used

to peg the beginning of the Anthropocene.

 

These " chemical signals " at a specific depth in the Earth's upper crust are

unique to the modern era, he said.

 

Altering official categories of Earth history is no small matter. Debates are

still raging in geological circles over when, precisely, the Holocene began and

the Pleistocene (popularly known as the Stone Age) ended. Another battle is

being waged over when, exactly, the Tertiary gave way to the Quaternary about

1.9 million years ago.

 

Those battles, though, are confined to the rocks-and-minerals crowd. A

declaration that the Holocene is over and the Anthropocene has begun would send

a powerful message to all of humanity that people and their machines -- more

than climate patterns or seismic activity or ocean currents or other non-human

forces -- are now the prime actors in changing the face of the Earth.

 

" It's an interesting idea, " said James Ogg, a Purdue University geologist and an

executive member of the International Commission on Stratigraphy. " It's very

important in that it does bring out that we have become a major geological

agent. "

 

Mr. Ogg said he is " doubtful " the proposal for a separate epoch would be

ratified by the world body, but he suggests that formally declaring the

Anthropocene a distinctive " phase " of the Holocene is a possibility.

 

" When I look out the window, what I see is all man-made material. "

 

© The Ottawa Citizen 2008

 

 

What gets us into trouble is not what we don't know, it's what we know for sure

that just ain't so.

- Mark Twain