Increasing Glaciation

As we all know, things are going to get worse before they get better: The Northern Hemisphere is in for a period of increasing glaciation during the next few thousand years. That is the conclusion of three researchers reporting in the December 10, 1976, issue of Science magazine. The three, J. D. Hays, John Imbrie and N. J. Shackleton, have examined the geologic record over the past 450,000 years by analyzing drill cores of sediments on the floor of the South Atlantic Ocean. By measuring the relative abundance and composition of life species in the sediments and being able to date when the sediments were laid down, they were able to obtain an index of the global climate over the 450,000-year period.

The scientists found cyclic variations in the climate that they could relate both to periods of glaciation and to cyclic variations in the earth's orbit. Wobbling of the earth's rotation axis (period 41,000 years), shift of the date of the equinoxes (period 21,000 years) and change in the degree of circularity of the earth's motion about the sun (period 100,000 years) all are found to be important. By extending the past behavior into the near future, Hays, Imbrie and Schackleton predict a long term trend over the next 20,000 years toward extensive glaciation and cooler climate.

Assuming the correctness of the prediction, the effect on Alaska will be profound. Many mountain valleys will again become ice-filled. Ground transportation corridors through the Alaska Range and the Brooks Range will be closed. As more sea water is tied up in ice, the coastlines will expand outward and the Bering Land Bridge will reappear. Someday it will be possible to drive a car past Nome to Moscow.