The new air world

by Willis L. Moore

It follows that if the Rocky Mountains were lowered as described, the entire United States would be green with rich vegetation and there would be no deserts anywhere within its broad boundaries. Also, if the Appalachian Range were as high as the Rocky Mountains—as it may have been at one time—and if it extended around the Gulf of Mexico as well as up through our Atlantic Coast States, the vaporous atmosphere of the Atlantic Ocean and of the Gulf of Mexico would be prevented from entering the interior of the continent, and the power that to-day stands as the greatest bulwark of civilization would not exist. There would be but a narrow fringe of vegetation upon its east and its west coasts; the interior, with its vast cotton and cereal plains, would be a barren waste.

But to revert for a moment to Jefferson. He took his thermometer to Philadelphia when he proceeded there on a mission that would have caused any less serene and courageous spirit to forget all the small details of life. When the debates upon which hung the fate of a nation and, in fact, the lives of those that participated, were in progress, he coolly hung his thermometer on the wall and noted down its readings. Those historians who have described the intense heat in Independence Hall on the Fourth of July, 1776, were mistaken, as will be shown by reference to his observations, the early and the late ones of which doubtless were made at his lodgings. They are as follows: 6 A.M., 68°; 9 A.M., 72¼°; 1 P.M., 76°; and 9 P.M., 73½°.

Jefferson had one of the only two barometers in this country at that time. James Madison (the Bishop, not the President) had the other. They took readings at the same hour of the day for a considerable period of time, and Jefferson discovered that changes in the pressure of the air always began on his instrument a few hours before they did on his friend’s instrument a couple of hundred miles to the east of him. He came near discovering the fact that no matter what the direction of the wind, storms almost universally move from the west toward the east. When the British captured Washington they also raided Monticello, Jefferson’s home in Virginia, and they destroyed his barometer. It has been said that he was as much distressed over the loss of his special instrument of science as he was over the burning of the National Capitol.

In “Descriptive Meteorology” (Appleton), the writer expressed doubt that there had been important changes in climate within the period of authentic history, but recent researches cause him to change his opinion, for the evidence now seems almost conclusive that marked changes have occurred. The powerful kingdoms of Sumeria, Babylonia, Assyria, and Persia, each ruling many centuries and dominating all or a large part of the vast region from the Persian Gulf to the Caspian Sea and westward to the Mediterranean and Egypt, covering in their various reigns some four thousand years before Christ, could hardly have built their many great cities, supported their numerous millions of population, and developed the trade and commerce that was theirs with the climatic conditions as they exist to-day. As late as the opening of the Christian Era, Palmyra, in Syria, had a population of from one hundred and fifty thousand to two hundred thousand people, was opulent and adorned with a comparatively high civilization. To-day we see the wreckage of its vast aqueduct and irrigating systems, which are unable to gather enough water to wet their well-constructed walls, and a few hundred people eke out a miserable existence where once was a metropolis teeming with life under luxurious conditions. The same picture is shown in more or less relief throughout the greater part of the region that once maintained the greatest empires of antiquity. But we must not assume that such dry and nearly barren conditions are to continue forever; rather are we to imagine that within a cycle of a few thousand years this region may have a rebirth of abundant vegetation and again throb with the pulsations of abounding life.

The record inscribed by the waters on the abandoned and the submerged shores of inland lakes and seas in the Rocky Mountains, and on the shores of the Caspian Sea and other waters, is easy to read. It shows several great oscillations of climate in the United States and the most civilized portions of the world since the birth of Christ. For some time before and for several centuries after the beginning of our era there was a wet period. The Caspian Sea stood some one hundred feet higher than now and an abandoned beach and a clearly marked shore line show that Lake Owens, in California, on the east side of the Sierras, existed at a level nearly two hundred feet higher than now. There was an abundance of water to irrigate the Holy Land, and although the center of dominating human power had long since passed in succession Babylon, Assyria, Persia, Greece, Macedon, and was working its way towards the Atlantic, the Mesopotamian Valley was abundantly fruitful.

Then, for six or seven hundred years, with short-period variations of from thirty to fifty years, the world inhabited by civilized man and large areas in the temperate zone not yet civilized, grew drier. The Caspian Sea fell to a lower level than it now maintains, for the ends of great walls, constructed to keep out barbarians, and other evidences of the handiwork of man, are now many feet below the surface of the water. This is the driest time known to history. Ellsworth Huntington of Yale, acting under the auspices of the Carnegie Foundation at Washington, made an examination of many of the stumps of the big trees of California, ranging in age from one to four thousand years. The thickness of each ring of annual growth is a legible record of the wetness or the dryness of the year. One would hardly think of these towering giants of the floral kingdom as being both thermometers and rain gauges, accurately measuring and recording the dry-hot and the wet-cold periods for thousands of years, and now at the end of their majestic careers revealing the hidden secrets of past ages. Huntington and Cushing, in “Principles of Human Geography”, say:

“The rings dating from the time of Christ are thick and indicate that at that time, when Palmyra had an abundant supply of water, when Owens Lake overflowed and there was high water in the Caspian Sea, the big trees also had plenty of water and grew rapidly. Six or seven hundred years later, when Palmyra was abandoned and when the Caspian Sea stood fifteen or twenty feet lower than at present, the trees formed only narrow rings, because the climate was dry. The way in which the growth of the trees has varied is shown in [Figure 30]. The high part of the curve indicates abundant rainfall. The black shading at the bottom indicates periods of comparative aridity.”

Fig. 30.—Changes in Climate in California during the Christian Era. Black shading indicates Drought.

Since the extensive system of observations by the Weather Bureau was inaugurated, some fifty years ago, it has been revealed to us that frequently the Ohio Valley would suffer a deficit in rainfall that would persist for periods as great as five or six years, while New England and the South Atlantic States, or other large areas of the country, had an excess. This is an illustration that excesses in one part of the country were balanced by shortages in other parts that occurred at the same time. But the long-period oscillations in climate that are measured in hundreds of years instead of tens—these changes seemed to have occurred simultaneously in the middle latitudes of Europe and America. These changes were simultaneous in an east and west direction. Now we have evidence of such long-period changes in a north and south direction which were simultaneous, but of an opposite character, indicating that during the Christian Era the eastward track of storms has oscillated northward and southward. This would account for the occurrence of dry and of wet periods simultaneously throughout the vast stretch of territory between southern California and the Caspian Sea. In Guatemala, Yucatan, and other Central American countries there are ruins of cities and the evidence of an agriculture and a civilization that could not have been established with the torrential rains and jungle growths that now prevail in those regions. During the centuries when the big trees of California were receiving a large rainfall and making a thick annual growth, especially about the beginning of the Christian Era, because of a northward shifting of the climatic zone, the precipitation in Yucatan and Guatemala had so diminished as to leave only the amount of rainfall that could be economically employed in agriculture and in the rearing of great cities; and then, with a southward migration of the rain belt, these cities were suffocated with excessive precipitation, agriculture rendered impossible, and their temples and palaces buried beneath the gloom of a tropical growth.