From Harper's Magazine:
The Coming Ice Age
THIS is the story of two scientists, who started five years ago — with a single radiocarbon clue from the ocean bottom and a wild hunch — to track down one of the earth’s great unsolved mysteries: What caused the ancient ice ages? Their search led over many continents and seas, to drowned rivers and abandoned mountain caves, into far-removed branches of science. It took them down through recorded history, from the stone tablets of primitive man to contemporary newspaper headlines.
These two serious, careful scientists — geophysicist Maurice Ewing, director of Columbia University’s Lamont Geological Observatory, and geologist-meteorologist William Donn believe they have finally found the explanation for the giant glaciers, which four times during the past million years have advanced and retreated over the earth. If they are right, the world is now heading into another Ice Age. It will come not as sudden catastrophe, but as the inevitable culmination of a process that has already begun in northern oceans.
As Ewing and Donn read the evidence, an Ice Age will result from a slow warming and rising of the ocean that is now taking place. They believe that this ocean flood — which may submerge large coastal areas of the eastern United States and western Europe — is going to melt the ice sheet which has covered the Arctic Ocean through all recorded history. Calculations based on the independent observations of other scientists indicate this melting could begin, within roughly one hundred years.
It is this melting of Arctic ice which Ewing and Donn believe will set off another Ice Age on earth. They predict that it will cause great snows to fall in the north — perennial unmelting snows which the world has not seen since the last Ice Age thousands of years ago. These snows will make the Arctic glaciers grow again, until their towering height forces them forward. The advance south will be slow, but if it follows the route of previous ice ages, it will encase in ice large parts of North America and Europe. It would, of course, take many centuries for that wall of ice to reach New York and Chicago, London and Paris. But its coming is an inevitable consequence of the cycle which Ewing and Donn believe is now taking place.
A bit more:
“We suspect that the ocean is already warm enough to melt the Arctic ice sheet,” Ewing and Donn told me. “For some time it has remained at the highest temperature ever reached in the four previous interglacial stages.” As climate becomes warmer, more and more glacial melt-water pours into the sea. The Atlantic has already risen 300 feet since the glaciers of the last Ice Age started to melt away. Up until twenty-five years ago the U.S. Geodetic Surveys indicated that sea level was rising six inches a century; in the past twenty-five years that rate has increased to two feet a century.
As sea level rises, more and more warm water pours over the Norway-Greenland sill, under the Arctic ice sheet. American, Russian, and Scandinavian scientists have observed a definite warming of the Arctic Ocean over the past fifty years, and a consequent thinning of the ice sheet. At an international conference on Arctic sea ice in March 1958, scientists estimated that Arctic ice covers an area 12 per cent smaller than it did fifteen years ago, and is 40 per cent thinner. A layman might surmise that if this trend continues the Arctic Ocean will be open and the Ice Age begin in another twenty years. Ewing and Dunn are much more cautious about predictions.
The article concludes with this:
Ewing and Donn don’t know how much higher the sea is going to rise before it melts the Arctic ice sheet. They say the ocean has already risen to the point where, if certain recent storms had occurred at high tide, it would have flooded New York and Boston subways. Donn is now working at Lamont on studies of long and short period changes in world sea level.
The ocean flood that brings about the Ice Age will not resemble the flash floods that have caused havoc in the cast in recent years. It will build up slowly, and it will not flow away. The cities, industries, and military bases that are concentrated on both sides of the Atlantic may have to be evacuated. (Fortunately, Pacific coastlines are higher.)
It will probably be possible to protect New York and Washington by levees. Parts or all of New Orleans, Amsterdam, Rotterdam, and other cities are now protected by levees from high water, Ewing and Donn point out. Evidently, New York is in no danger of becoming a lost Atlantis, drowned under the sea. If low-lying Brooklyn, Miami, Washington, New Orleans, or Amsterdam should become ghost cities, it will be because a decision will have been made long in advance of this slow-creeping flood to evacuate rather than build levees.
“According to our theory, with the melting of the Arctic ice sheet, the rise in sea level will stop,” Ewing and Donn explained. Instead of adding water to the sea, the glaciers will begin taking it out.
For a long time after the ocean flood subsides, the only effect the Ice Age will have on us down here will be more rain. The new Arctic moisture that falls as snow on the glaciers will increase both rain and snow here, swelling rivers and watering deserts. Then, gradually, our weather will cool. Icy winds will blow from the advancing glaciers; the great snows will fall farther and farther south. In several thousand years a two-mile ice sheet may cover the United States and Europe. If man finds no way to switch the glacial thermostat, there may well be a real estate boom in the Sahara.
You might have guessed that this is not a new article - it was published in September 1958
I love that bit about the melting Arctic ice affecting the sea level. Take a glass of ice water, mark the level of the water and wait for the ice to melt. Still at the same level? Yup! Clueless then, clueless now and there is nothing we can do about it either way.
And the current consensus seems to be favoring another little ice age - our sun is entering a quiet phase. More here, here, here and here.