Are We Heading for Another Ice Age?

As firmly established as the science of glaciology is today, it seems strange that as recently as 150 years ago, the very existence of glaciers was a matter of hot dispute.

The evidence left by ancient glaciers was all around--grooved and polished bedrock, landforms composed of glacial debris such as moraines and eskers, jagged mountain peaks, deep valleys, even certain lakes and rivers. However, it was argued that glacial features were not produced by ice, but by the action of ancient water--the ever-popular, all explanatory Biblical Flood.

This presented some problems. For instance, debris was not sorted by size as it is by flowing water, and huge boulders the size of houses were often found transported great distances from their point of origin. Because of these and other anomalies, Charles Lyell, a leading British geologist, was the first to propose an ice-related origin in 1833. It was his suggestion that the large boulders had been transported inside icebergs from the North Pole carried by--you guessed it--the Flood.

Lyell was off the mark, but his idea contained at least a grain of truth: ice can transport boulders.

While this notion was novel to scientists, it was a long-established fact to the farmers and villagers who lived in the glacier-studded Alps. For generations these people had watched glaciers retreat and advance, even to the point of encroaching on their farms and settlements. From first-hand observations they knew that the ice moved, that it gouged and polished rock, and that it deposited rocky debris as it retreated. But the sensible observations made by the peasants were ignored by the scientists.

Enlightenment finally began to spread through the scientific community in 1837, when Louis Agassiz, president of the Swiss Society of Natural Sciences, first addressed the possibility of an "Ice Age." He saw an "epoch of intense cold," during which all life perished under an enormous ice sheet which descended from the North Pole and extended over much of the northern hemisphere. Even though we now know that the ice did not come from the North Pole, this was a step in the right direction, but it was widely resisted because of diehard adherence to the old Flood notion.

Ironically, it was Agassiz' concept of global glaciation which led him into direct conflict with Charles Darwin. While Darwin was one of the first scientists in England to accept Agassiz' radical ideas, Agassiz was violently opposed to the concept of evolution. This is why he insisted, irrationally, that the ice sheets had destroyed all life, and that there could therefore be no direct link between species of the past and present. The Creator must have started all over again after the Ice Age, maintained Agassiz.

We now know, of course, that there was an ice age, but that all life was not destroyed. As a matter of act, there have been several ice ages. A century of research since Agassiz' death in 1873 has established that during the last million years, there have been at least four, and perhaps as many as ten periodic invasions of ice around the world. The last of these, known as the Great Ice Age, began about 70,000 years ago, peaked at about 20,000 years ago, and ended 8,000 years ago when the glaciers shrunk to approximately their present-day limits.

Since the Great Ice Age ended, there have been intermittent periods of glacial expansion. The most recent of these began in the 15th Century. Because the glaciers had appeared stable for many years, Europeans felt safe in building their homes near the edges of the ice, only to have then bulldozed under when the glaciers began a sudden advance. Over the next 450 years, until the mid-1800s, the cold was so severe and the glacial expansion so pronounced that the period is sometimes called the Little Ice Age.

Since 1850, we seem to be in a period of glacial retreat coinciding with a worldwide increase of about 1°F in mean temperature. Beginning in the 1940s, however, glaciologists have noted a widespread slowdown in glacial retreat and numerous examples of expansion.

In Alaska, although 63 percent of the 200 glaciers measured were retreating, seven percent were advancing and 30 percent were holding their own.

While many scientists believe that the future holds another ice age, most agree that the present interglacial period will last for at least another 2,500 years.