| Short walk to the next age
iCE AGE By John and Mary Gribbin,
Allen Lane, £ 6.50
John and Mary Gribbin begin their book with the astounding statement that in terms of the geological past we are still living in an Ice Age. This might be difficult to stomach in the sweltering Indian summer but the operative part of the statement is the geological past. The world was colder than what it is today, not so long ago. And unless something remarkable happens, in the realm of innovations made by human beings, the globe will cool again. Geologists say that the history of human civilization embraces only a “short-lived, temporary retreat of the ice, an Interglacial.” All of human vanity and the drama of human life are thus caught between two enormous glaciers.
The Gribbins tell the fascinating story of how the Ice Age came to be discovered by scientists not known outside a select cognoscenti. The heroes of their narrative — Louis Agassiz, James Croll, Milutin Milankovitch, the pioneers of the Ice Age theory — are nowhere as well- known to the intelligent layman as Kepler, Galileo and Newton, the three fathers of modern physics.
The two principal remnants of the Ice Age are the polar ice caps. But they haven’t been there from ever since the world began. They are roughly co-terminous with human civilization or to put it in another way, their existence has made us human. Ocean currents, crucial determinants of climate, cannot reach the poles. The warm waters of the Gulf Stream cannot reach the North Pole. If the Gulf Stream could go beyond Greenland, the Arctic region would be warmer by six degrees Celsius and this would change the entire climate of the Northern hemisphere. This is only one instance of how crucial the existence of ice is for the world.
The search for the Ice Age did not begin, however, with the two poles. It began with the study of erratic boulders, lumps of rock lying around in places far from the strata to which they belong. One theory was that they have been brought there by the Flood or some other catastrophe. But others have argued that these were dumped by glaciers in retreat. This theory was first championed by Bernard Kuhn and James Hutton in the late 18th century. Agassiz, a Swiss born in 1807, began on this and as the president of the Swiss Society of the Natural Sciences, he propounded the idea of the Ice Age. Advances in astronomy showed that changes in the earth’s tilt affected climate. The two masterminds of the astronomical models of the Ice Age were Croll and Milankovitch.
It was Croll who first suggested in a remarkable piece of insight that the bottom of the ocean was the best place to look for clues for what the climate of the earth was in the past. Studies of the sea were hampered by inadequate technology. Advances in this technology, the consequent analysis of fossils and the synthesis of these findings with the astronomical theory produced the final confirmation of the Ice Age in the Seventies.
The escape from Ice Age conditions began only 18,000 years ago and the earth came into a peak of warmth only 6,000 years ago. This book shows that human beings came into existence about 4 million years ago exactly at the same time as the climate began to change dramatically. There is thus a coincidence between evolutionary time and environmental time.