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Wednesday, February 06, 2008

Are We Living in the Anthropocene?

The Earth's rock layers tell us stories about our natural history; most recently the layers tell us stories of undeniable, human-induced global environmental change. This month, the Geologic Society of America (GSA) publication GSA Today features an article authored by a sizable group of geoscientists from London who suggest that we have so profoundly altered our planet since the Industrial Revolution that human activity has left, and will continue to leave, a permanent imprint on the Earth's stratigraphic record (see figure to left).

They suggest that these changes are on such a large scale that we have entered a new geologic epoch defined and dominated by human activity. They further propose that we officially rename our current epoch the Anthropocene. The Anthropocene was originally suggested in 2002 by Nobel laureate Paul Crutzen who won the prize in 1995 for his work on the depletion of ozone... and geologists have casually referred to this time as the Anthropocene for quite some time.

"Humans have caused a dramatic increase in erosion and the denudation of the continents, both directly, through agriculture and construction, and indirectly, by damming most major rivers, that now exceeds natural sediment production by an order of magnitude."
There are visible changes to our oceans (an increase in acidity due to carbon release), as well as major biotic changes (extinction events)...

They suggest we may enter a "super-interglacial," with Earth reverting to climates and sea levels last seen in warmer phases 1-5 million years ago. They also discuss stratigraphic evidence found today that is similar to other major geologic time boundaries (including the mass extinction that occurred at the K/T boundary).

"The combination of extinctions, global species migrations, and the widespread replacement of natural vegetation with agricultural monocultures is producing a distinctive contemporary biostratigraphic signal. These effects are permanent, as future evolution will take place from surviving (and frequently anthropogenically relocated) stocks."

The evidence for human-induced global warming surrounds us; it is in the air we breathe, the oceans we travel, and even in the rock beneath us. The stories the Earth tells us will continue to be written; we will continue to shape the stratigraphic record, and we can choose to stop our reckless release of global warming pollution, and avoid the looming mass extinctions and further degradation of our natural resources.

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