Living on the Ice Shelf: Humanity's Meltdown
By Mike Davis
1. Farewell to the Holocene
Our world, our old world that we have inhabited for the last 12,000 years, has ended, even if no newspaper in North America or Europe has yet printed its scientific obituary.
This February, while cranes were hoisting cladding to the 141st floor of the Burj Dubai tower (which will soon be twice the height of the Empire State Building), the Stratigraphy Commission of the Geological Society of London was adding the newest and highest story to the geological column.
The London Society is the world's oldest association of Earth scientists, founded in 1807, and its Commission acts as a college of cardinals in the adjudication of the geological time-scale. Stratigraphers slice up Earth's history as preserved in sedimentary strata into hierarchies of eons, eras, periods, and epochs marked by the "golden spikes" of mass extinctions, speciation events, and abrupt changes in atmospheric chemistry.
In geology, as in biology or history, periodization is a complex, controversial art and the most bitter feud in nineteenth-century British science -- still known as the "Great Devonian Controversy" -- was fought over competing interpretations of homely Welsh Graywackes and English Old Red Sandstone. More recently, geologists have feuded over how to stratigraphically demarcate ice age oscillations over the last 2.8 million years. Some have never accepted that the most recent inter-glacial warm interval -- the Holocene -- should be distinguished as an "epoch" in its own right just because it encompasses the history of civilization.
As a result, contemporary stratigraphers have set extraordinarily rigorous standards for the beatification of any new geological divisions. Although the idea of the "Anthropocene" -- an Earth epoch defined by the emergence of urban-industrial society as a geological force -- has been long debated, stratigraphers have refused to acknowledge compelling evidence for its advent.
At least for the London Society, that position has now been revised.
To the question "Are we now living in the Anthropocene?" the 21 members of the Commission unanimously answer "yes." They adduce robust evidence that the Holocene epoch -- the interglacial span of unusually stable climate that has allowed the rapid evolution of agriculture and urban civilization -- has ended and that the Earth has entered "a stratigraphic interval without close parallel in the last several million years." In addition to the buildup of greenhouse gases, the stratigraphers cite human landscape transformation which "now exceeds [annual] natural sediment production by an order of magnitude," the ominous acidification of the oceans, and the relentless destruction of biota.
This new age, they explain, is defined both by the heating trend (whose closest analogue may be the catastrophe known as the Paleocene Eocene Thermal Maximum, 56 million years ago) and by the radical instability expected of future environments. In somber prose, they warn that "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." Evolution itself, in other words, has been forced into a new trajectory.
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