Real Climate Records

Polar Areas Once Torrid

A STUDY of the fossil beds of the rock formations of the polar regions discloses the startling fact that glacial and ice conditions have been the exception and not the rule in polar areas.

They have been essentially warm areas. The testimony of the polar rocks states that they have mainly been areas which supported torrid and tropical animals and plants until in comparatively recent times they were visited by the ice.

There is no evidence of the rocks of the polar areas being glaciated or marked by ice earlier than the Eocene era. We must therefore infer that the glaciers of Greenland and the Antarctic, in ad-

dition to being the greatest in existence today, are the youngest of modern glaciers. In them only can we witness the early characteristics of glacial action.

Every modification of glacial activities is followed by climatic modifications. Climate is always reciprocally related to glacial movements. It is estimated that when the course of the Baltic Sea

was changed about 6,000 B.C. by this elevation of the land which now forms the Kingdom of Denmark, the climate of Europe was marked by great variations in temperature between summer and winter.

The climate was then very warm in summer and cold and stormy in winter. When about 4000 B.C. the Baltic waters again began to flow into the North Sea as at present, a low annual temperature range and increased rainfall resulted. We have good reasons for believing that

in California and other Western States the climate at that time underwent similar modifications to those in Europe owing to changes in the course of the Alaskan current. These climatic

changes indicate that they are caused by purely local dynamical movements and also in some cases by vast geographical changes in the whole hemisphere.

There appears to be a definite relationship between the 11-year sun-spot phenomena and terrestrial weather cycles which manifest themselves in modifications in glacial activities. At sun-spot maximum atmospheric circulation is intense, causing much storminess and rain. American storms then travel further south and the winters are severe. But in the tropics the temperature is low during the maximum sun-spot periods, and there is less radiation.

Selective Radiation

THE earth’s climate is also modified by the amount of heat radiation from the earth into space and by absorption in the atmosphere of the earth’s long wave radiation. The earth as a whole is warmed or cooled according as the radiation from the sun to the earth or from the earth into space is the greater. Cooling may be caused by an absorbant dust in the air taking more heat from the wave length of maximum energy radiated from the sun than from the radiation of the earth.

Volcanic dust carried in the air often acts as a refrigerator of this character by absorbing the sun’s radiated heat and protecting the earth from it. Variations in the gaseous constituents of the air and in their stratification also bring about profound temperature changes. Ozone is formed in vast quantities in the upper air by ultra-violet radiation and large layers of ozone are more strongly selective of solar radiation than the earth. This selective radiation by ozone, and perhaps by other atmospheric gases, appears to be always in progress, and is the cause of many of the strange changes that occur in local weather cycles.

The cloud mists and fogs, as well as auroral and other magnetic phenomena, appear also to exert influences in changing the earth’s solar absorption and consequently in bringing about climatic changes that have important influences upon the state of the icefields at any given time.

The whole mechanism of glaciation and climatic changes and weather cycles is exceedingly complicated. They are, however, clearly based upon three fundamental factors, viz.: Mountain

building and land elevation, volcanic activity and the scattering of volcanic dust in the atmosphere, phenomena of solar and earthly radiation, and geographical land and sea changes. When these all combine and operate together in one objective manner the whole climate of, the earth may be modified either by the establishment of a new glacial epoch or a tropical one. Acting singly, they are no more significant of important changes than the most marked variations in the speed or size of any particular glacier.

There is nothing in the present conditions of the earth’s climate to show that important modifications are to be expected. There will be other ice ages on earth, but the next one is quite far off.

Present indications show that the earth is losing ice rather than accumulating it.