Prospective dry years and their cause

Many kinds of geological phenomena clearly record important climatic cycles of different lengths, but until very recently the length of none of these cycles had been accurately determined. By means of annually deposited layers of sediment (varves) in the ocean, it has been possible to find many lengths of cycles in rock-strata, and to show that those of shorter length agree with cycle-lengths found in tree-rings and in varves in existing lakes. The author has recently completed a field-study of climatic cycles recorded in rock-strata from the northern part of the United States to the southern part of Mexico. The results of this investigation, combined with those of previous studies, are given in a Table of cycle-lengths and dates. The Table contains four important triple-progression series of cycles, all of which are harmonic. Three of the long climatic cycles are shown to have produced a downward trend in rainfall in many regions culminating in a series of droughts, beginning about 1930. This series of droughts will probably continue till about 1990, judging by the cycles responsible for it. In many regions these droughts bid fair to be more severe than any long series that has occurred in the last 20 centuries. It will therefore prove futile to continue the present policy of “relief in the dust- bowl regions.” Wholesale migrations from those regions seem advisable. Weather-records kept by man go back too short a time to be of much use in forecasting climatic changes. Only climatic cycles recorded by Nature (for example, varved rock-strata, recessional moraines of glaciers, lake and marine terraces, lake and marine varves, tree-rings, etc) can be used effectively to solve the problem of long-range forecasting. Yet neither our Weather Bureau nor that of any other nation has ever made a systematic study of these natural records of cyclic changes, and only a few scientists have done much along this line. The author presents four laws relating to cyclic phenomena, and comes to the conclusion that not only weather-cycles but many other types of radically different cyclic phenomena are concurrent effects of cyclic bombardments of the Earth by solar electrons. Among the many correlated terrestrial cycles are those of rainfall, earthquakes, magnetic storms, auroras, declination of the compass, changes of sea-level, changes of the rate of axial rotation of the Earth, and showers of meteors. Local weather-changes are, as yet, much more difficult to forecast by aid of cycles than are climatic changes over great areas. This is proven by “predicting backward,” that is, by explaining past changes by the aid of cycles. The author gives an example of “predicting backward” by showing how three long cycles in his Table explain the long dry period near the close of the 18th Century. He points out that storm-tracks tend to shift to lower latitudes near maxima of rainfall-cycles, often producing opposite effects in different localities. Because all cycles are harmonic, long cycles are built up by the combined effects of short cycles, and consequently the longer the cycle the greater its amplitude. This explains why long cycles are so conspicuous in geological phenomena, a careful study of which removes any skepticism as to the probable value of long cycles for forecasting purposes.