Other mysteries solved
CHAPTER FOUR
OTHER MYSTERIES SOLVED
Causes of Climatic Changes
It is the concensus of scientists that all glacial episodes were of short duration; that they were followed by mild climatic conditions; that the latter were the rule throughout interglacial periods. It is the orthodox belief that accumulation of glaciers resulted from slow deterioration of climate. The corollary of that belief is that subsequent disappearance of the glaciers was due to warming up of climate.
As we have noted, a hundred years of study and speculation have failed to produce a tenable reason for deterioration of climate. The true explanation is, as we shall see, that climate did not grow colder prior to arrival of the ice; it grew colder afterward and because of the ice.
In area, the ice sheets aggregated more than one-third of the present total land area of the globe. There can be no doubt that, in addition to what snow and ice fell upon land, great quantities also fell into the oceans. It cannot be doubted that such an inconceivably vast quantity of ice and snow was fully capable of destroying or greatly modifying faunal and floral life forms of land, sea and air. Scientists have made the error of assuming that discernable changes in life forms prove that climate grew colder before the arrival of the ice.
Strangely, very little, if any, attempt has been made to explain why climate warmed up after a cold glacial spell. Virtually all efforts have been to find out why climate grew colder. However, as the latter efforts have failed, even after a hundred years of study, it can scarcely be expected that the cause of subsequent amelioration could have been determined even by an equal amount of study.
A phenomenon even more intriguing than the foregoing is why and how zonal differences in global climates could have been so much less pronounced in past geological periods than they are now. The concensus is that during the greater part of past time, mild, temperate-type climate extended much farther toward both poles than it now does; in fact, that it extended even to within both polar circles. As an example of this belief Barghoorn, speaking of the Carboniferous period, says (paper in Shapley’s Climatic Change, p. 241):
From the paleontological evidence available, it would appear that there was very slight climatic zonation between high and low latitudes during the major part of the Carboniferous.
Yet scientists are also agreed that climatic temperatures in the torrid zone were not much, if at all, warmer than they are now. Dr. Bell says (Solar Variations, p. 132):
It is by no means clear that solar radiation sufficiently intense to keep the poles as warm as they appear to have been at times would not heat the tropics more than observations indicate.
Planets Explain Zonal Uniformity
Astronomers, geophysicists, geologists and other scientists alike, have been quite unable to conceive an explanation of the astonishing uniformity of past climates in all zones of latitude. Actually, of all writers who have commented about the mystery, very few, if any, have made any serious attempt to account for it. Had it but occurred to any one of them to take a good look at Jupiter or Saturn, and reflect upon the implications inherent in conditions plainly visible on those planets, surely he would have conceived the true explanation of why comparative uniformity of zonal climates was the rule throughout most of geological time; why it was broken only at irregular intervals by glacial episodes; and why mildness and uniformity of climate returned after every glaciation with the exception of the last one. He would have realized that such absence of zonal influence upon climate can never again eventuate.
A thorough study of Jovian or Saturnian conditions would have convinced him that the clouds which obscure those planets can be nothing but tenuous envelopes of discrete aqueous and other mineral particles, revolving quite apart from the cores. This conception would have brought realization that if Earth in the past was similarly blanketed, a hothouse effect would have resulted and climatic temperatures would have been raised and made more uniform in all zones of latitude.
Some theorists, in trying to imagine conditions which would cause lower climatic temperatures, have suggested that excessive volcanic or cosmic dust in the atmosphere would effect such a result. This is contrary both to evidence and logic. Cloudy nights are always warmer than clear nights. The roof of aqueous vapor on a cloudy night retards escape of solar heat. A tenuous mantle of water or mineral matter suspended far above and completely enshrouding the globe would let solar heat penetrate through but would retard its escape. The shroud would diffuse the heat and make temperatures more uniform from pole to pole. It would increase humidity, while at the same time reducing atmospheric currents and sudden temperature changes. It would foster rank growth of floral, even animal life, world-wide. Sunlight, reflected from the brilliantly illuminated atmospheric envelope hundreds or thousands of miles above Earth’s surface, would supply twenty-four hour life-giving daylight from pole to pole, winter and summer alike. There would be no nighttime as we know it on the hemisphere opposite the sun.
Barghoorn says (op. ctt., p. 243):
The development of coal-forming swamps close to the South Pole demands an explanation allowing for extraordinary climatic change. Botanically also, Jurassic floras present the curious anomaly of a well-differentiated vegetation developing under physiologic conditions of a polar night.
The explanation Barghoorn demanded is clearly furnished, the anomaly he pondered is definitely disposed of, by recognition of the influence which a primordial cloudy shroud would exert upon global climate.
Future Uniformity Impossible
It seems to the writer that in no other way is it possible to account for greater uniformity of climate, from pole to pole, which we positively know has obtained throughout most of geologic time. In passing, let us note that such uniformity can never again eventuate, because no longer is there, or can there be again, such a hothouse roof of aqueous or other mineral matter to insulate the atmosphere. Although the latest Pleistocene ice has steadily dwindled and is still slowly melting away, it appears probable that earlier ice sheets disappeared more rapidly because the Earth was still blanketed wholly, or at least partially, by remnants of primordial clouds.