WORLD GROWS DRY

Evening Star, Issue 22457, 30 September 1936, Page 10

WORLD GROWS DRY

MARCH OF THE DESERTS LAKES WHICH ARE VANISHING By some strange antinomy of Nature, while Britain and Isortlx-west .Europe suffered from, a dismal plethora of ram, drought of an unprecedented severity burnt up an area or more than half a million square miles in the richest wheat lands of Mid-western Canada and the mid-western section of the United States (wrote H. W. .Wilson, in the ‘ Daily Mail recently). This drought seems now at last to be fading out. But the damage which it has done to the lb States and 550 counties afflicted is probably not less than £100,000,000 in value. . And the most alarming fact in connection with it is that it points to the conclusion that the climate of the United States is changing, and that in present conditions the whole affected area is becoming too dry for cultivation. . The very soil is vanishing. Reduced to a fine powder by the intense heat, it is blown'away in fierce 'dust storms. This is not the first such drought in recent years, it is the third since 1930, though of 1934 American meteorologists predicted a long run of favourable years. Their forecasts have been disastrously at fault. There is an ever-accumulating mass of evidence in this connection to suggest that the earth is steadily becoming drier. VANISHING FORESTS. This increasing dryness is, no doubt, in large part due to the destruction of forests, which has been proceeding for the last 150 years at a terrific rate. But there may also be a contributory cause in an increase in the heat of the sun, which modern astronomers regard as a variable star. The temperatures recorded in the United States this summer have never before been equalled; 125 deg m the shade at a point so far north as Wilkes-Barre is startling. In the United States there has always been a large desert zone. Rut now it is growing in extent at a disquieting rate. .... .. . „ A similar process ot desiccation has for centuries been in progress in other parts of the world, and there are signs that it has latterly been accentuated. Professor Stebblifag last year gave an account of his investigations regarding the spread of the Sahara. 1 his most famous of all deserts is still extending its area rapidly. 1 It is moving southward at a rate ot more than half a mile a year, and has been doing this for three centuries, until to-day it menaces Northern Nigeria and the French Vest African colonies with disaster. Plain evidence of increasing dryness is given by the study of lakes. SHRINKING LAKES. The Great Salt Lake in the United States has shrunk enormously since prehistoric times. It was then a huge inland sea. 30,000 square miles in extent, whereas to-day its surface measures only 1,740 square miles. Let us look at Africa. Livingstone in 1849 discovered Lake Ngami, in what is to-day British Bechuanaland. Tt was then an imposing sheet of water. iU miles long, with a breadth of about nine miles. It has been shrinking ever since, and recent expeditions which have examined it found no water surSimilar is the record of Lake Chad, lying in Central Africa, near the southern edge of the Sahara. When it was first sighted by Europeans in 1823 its area was estimated at 40,000 square miles. During recent years the level of water' has fallen so much., that a town which in 1850 was on its shore was 20 miles from it in 1905. In Western Asia the Caspian Sea gives incontrovertible evidence that the world is drying np. Since 500 b.c. the level has fallen 100 ft. In its' movement through space the earth must gradually lose the gases in its atmosphere and its water vapour. MOLECULES FLUNG OUT. “ At the confines of the earth’s atmosphere,’ says the Astronomer Royal, “ there are molecules continually flung outwards with velocities of such magnitude that the force of the earth’s gravitation cannot hold them back.” The smaller the planet, the less its gravitational mass and the greater its difficulty in holding its water vapour aud its atmosphere. Thus Mars, with a gravitational hold on its molecules only one-fifth that of the earth, should show us, could we behold its world, what the state of the earth is likely to be centuries for aeons hence. [t was for that reason that the late Professor Lowell devoted his fortune and life to an effort to penetrate the secret of Mars and its mysterious canals.

'Studying them, he saw a dying race in a desert world —from which seas had vanished—trying to obtain water and to conduct it by gigantic works from the polar ice-caps in the droughttormented equatorial zone. Was he right ? Most astronomers reject his theories, but they would not deny that his vision had- more than plausibility in it or that decade by decade the earth is becoming drier; and that this cosmic process is being aggravated by the reckless destruction of forests which is still taking place. In fact, the “ Drys ” have it.