The Coming Ice Age

by C. A. M. Taber

In my previous explanations on the subject I have thought that, should the southern seas have remained at or near the same sea-level as now, through an ice period brought about in the manner I have described, ice-sheets would accumulate on the antarctic continent, and also on the southern lands of South America, sufficient to flow out into the sea and close the Cape Horn channel.

But further consideration shows the impossibility of the southern seas having maintained their present sea-level during the growth of frigid epochs which have left such ample traces of glaciers having extended widely over the lands of the high latitudes of both the northern and southern hemispheres. For it appears that the larger areas of land in the northern latitudes, embracing wide continents and large islands, must, during the growth of a frigid age, have increased the spread of glaciers many times greater in extent than could be obtained on the smaller lands of the high latitudes of the southern hemisphere.

For it is evident that the water evaporated from the sea and deposited in snow on the large continents and islands of the high northern latitudes during the growth of an ice period would, while thus diminishing the ocean waters, greatly increase the weight of northern lands. Therefore, the waters of the diminishing seas of the southern latitudes would be attracted into the northern oceans in opposition to the prevailing winds.

Thus it appears that the Cape Horn channel would be too much reduced at the perfection of an ice age to afford an independent circulation for the southern ocean, even without being filled by glaciers to the extent I have pointed out in previous essays. Still, to whatever dimensions the Cape Horn channel might be reduced at the perfection of a frigid period, the enlarged shores bordering its diminished waters would be covered by heavy glaciers that would flow into the shrunken strait, and so close it effectually. Thus the reduction of the Cape Horn channel during the advance of an ice age seems, on close consideration, to be a simple operation of nature, which in the normal course of events must have taken place.

As the closing of the Cape Horn channel has been considered by reviewers the weak and questionable point in preventing my views from gaining acceptance, it becomes necessary to be explicit concerning the manner in which the Cape Horn channel has in past ages been obstructed.

According to the charts prepared by John James Wild, the middle portion of the strait is represented as being over a thousand fathoms in depth; but, as far as I know, its true soundings have never been determined. The deep portion of the mid-channel is described as being narrow when compared with its whole breadth from Cape Horn to the antarctic continent.

And, when it is considered, with the growth of an ice age, how much of the ocean waters would be stored in the vast ice-sheets of the northern hemisphere, and consequently because of their weight a large portion of the diminished southern oceans would be attracted into the northern seas, it seems that the bottom of the shoaler waters of the Cape Horn channel, which now comprise so large a portion of its breadth, would be raised above the surface of the sea.

The one-hundred-fathom depth south of Cape Horn, now supposed to extend from longitude 70° west to 55° west, and southward to the latitude of 57°, would be a land supporting heavy glaciers for six hundred miles along the north side of the reduced channel during the advanced growth of a frigid age; and the same conditions would be obtained in the vicinity of the South Shetland. And when, in addition, we contemplate the great snow-fall of that region, and the consequent gathering of glaciers which would occur on the widened shores of the lessened channel, and the certainty of their flowing into the diminished strait, together with the immense icebergs of such an age grounding in the shoaled waters, it seems that the complete obstruction of the reduced channel would be accomplished.

While contemplating the conditions that would obtain while the Cape Horn channel was being reduced, it will be seen that the independent circulation of the icy southern ocean would be carried on to a considerable extent even after the narrowing strait was no longer able to afford space for wide drift currents, for the reason of the strong current that would be caused on account of the high ocean-level maintained by the westerly winds on the Pacific side of the diminishing channel, and the great low sea-level that would take place on its Atlantic side.

Still, as previously shown, it seems that during an advanced stage of the frigid epoch, the heavy glaciers from the enlarged northern and southern shores of the shrunken channel, together with the ponderous icebergs, blocking its waters, the closing process would at last be speedy and effective.