Cold spell near? Geologist digs deeper on climate change | Opinion – Rhode Islanders speak out on issues | Providence Journal
http://www.providencejournal.com/opinion/commentary/20131020-frank-wilson-cold-spell-near-geologist-digs-deeper-on-climate-change.ece
It is a book called “The Whole Story of Climate: What Science Reveals About the Nature of Endless Change” (Prometheus Books). The author, E. Kirsten Peters, is a geologist who says that what people are likely to have gleaned from media reports on climate change is “only one isolated part of a much longer and richer climate story.”
Climate science, with its computer models, is a Johnny-come-lately to the narrative. Not so geology. “For almost 200 years,” Peters writes, “geologists have studied the basic evidence of how climate has changed on our planet.” They work not with computer models but with “direct physical evidence left in the muck and rocks.”
Space constraints preclude any detailed summary of Peters’s accessible but jam-packed little book. But some take-aways can be noted.
The first thing to note, though, is that we could be long overdue for a cold spell. In recent geologic history, which stretches back a couple of million years — geologists have an expansive view of time — Earth’s climate has been characterized by long periods of bitter cold punctuated by brief episodes of warmth. “The cycle,” Peters notes, “is always a long period of cold followed by a much shorter period of warmth.” Specifically, the cold intervals last about 100,000 years, and the warm ones about 10,000. The period we are living in, called the Holocene, began 11,700 years ago, which makes it “no different at all from other brief, warm intervals in the Pleistocene,” the previous epoch that lasted those couple of million years.
Peters uses the analogy of a football field to help readers visualize all this. We in the Holocene are positioned at the edge of one of the end zones. The cold periods average about 5.5 yards, the warm ones about half a yard.
Another point Peters is at pains to emphasize is that climate change can be quite abrupt. Toward the end of the Pleistocene Epoch, northern Europe experienced a period of warming called the Allerod Oscillation that lasted about 1,000 years. The pollen record indicates that the “shift to renewed bitter cold took place very rapidly, certainly within a single human lifetime.”
Most of the publicity on climate change has focused on temperature, but precipitation patterns can be deeply worrisome, as well. The prelude to the so-called Little Ice Age came in the form of torrential rains that swept Europe in 1316. By the 1340s “really cold temperatures” had arrived, as well.
