Wednesday 22 January 2020

No Climate Change in South Africa

CAPE ARGUS - 1927, August 2
In this article, Dr. JR Sutton, of Kimberley, one of the foremost of the world's meteorologists, furnishes some interesting sidelights on the great drought.
There has been no change in the rainfall, and the climate of South Africa is what it has been for ages. "Our luck in the weather has been out" that is all. Rainmaking is pure quackery!
Drought in South Africa is no new thing. We have suffered badly enough from it in the past as we shall suffer again. In one sense there is drought over the greater part of the country every year, that is if we define the term in the way in which it is defined in the Meteorological Glossary issued by the Meteorological office in London: "Dryness due to lack of rain. According to the classification of the British Rainfall Organisation an absolute drought is a period of more than 14 consecutive days without one-hundredth of an inch of rain on any one day, and a partial drought is a period of more than 28 consecutive days the mean rainfall of which does not exceed .01 inch per day," - in other words a total fall of a quarter of an inch in a month would be a partial drought.
On this basis a place so well blessed with rain as Pretoria may be said to suffer from drought, absolute or partial, in the winter of almost every year. Also, in a season of good rains there may chance to be periods between the showers in which no rain in measurable quantity will fall for weeks together. 
As the term is generally understood up country, however, it implies a more or less lengthy period during which the fall is so much short of the average as not to be sufficient to grow the crops, or water the cattle, which do fairly well at other times; although there may not have been either sort of drought answering to the definitions. Anyway, definitions apart, there is no doubt that the Midlands, and beyond, have lately gone through an exceptionally bad time, and that conditions near to famine are abroad.
Naturally the cry that reverberates to the four winds, as it does every time that the rainfall is deficient, is that South Africa is drying up; and the rainmakers as usual muster on the horizon. "For wheresoever the carcass is, there will the eagles be gathered together." 
But neither history nor statistics support the idea that the country is generally more arid than it has been for ages. Early travelers in the parts now so distressed have left vivid records of conditions quite as bad as anything that this generation knows. Latrobe described the district of "Uitenhagen," when he saw it in 1816, as the most barren, desolate, unpromising desert he had seen in all South Africa.
Not that he had a very high opinion of the rest of the country. He thought that it was, and always would be, little more than a wilderness. William Rogers, writing some 23 years ago, has told of the terrible state of things in 1859 when water was so scarce that the people of Port Elizabeth were paying as much as 2s. 6d. a bucketful. The bed of the Great Fish River was dry for miles. The Buffalo River had shrunk to a mere trickle. And so on.
But 1862 was still worse - "like which for severity nothing has been seen since." Thus, times in the Midlands have been, and doubtless at some future time will be, worse than the present. To tell the truth the people of South Africa, depending on the yield of the land, are living from hand to mouth. Though betimes seemingly in the midst of plenty they are, nevertheless, ever on the brink of famine. The reason is to be found in the latitude, which is responsible for the bright and sunny days we like to tell other folks about.
"Sun-kissed Kimberley Calls" sounds well enough as a title for the most attractive publicity booklet given to the world by any Union Town; but there are times - as in 1897 - when the call may be to heaven, and them heaven forgive the contributors (I was one myself) to that same booklet. It is our fortune - at times our misfortune - to be in the latitude of the southern anti-cyclone belt.
This belt extends right round the earth on or about 30 deg. of south latitude; it is a region of normally high barometric pressure and no great cloudiness. Where it crosses the land the margins as, say, at Durban and Buenos Aires, and a few mountainous districts. The rule is that the rainfall becomes more and more scanty, going across the continents from east to west. there is a corresponding belt north of the Equator.
All the hot deserts of the world lie under these belts, the worst being north of the line, because the land areas there spread more widely. The rainfall, such as it is, is of summer thunderstorms type for the most part, and it comes when weather conditions weaken the anti-cyclone influence for a while. When these conditions are unfavourable there is drought.
Speaking a large, conditions are more often favourable in summer than in winter over our eastern and midland districts, since in the warm months the anticyclone tends to shrink into subdivisions which retreat seawards. In winter there is little of such tendency. Of late, as it happens, the anticyclone has reigned almost supreme. Day after day for some months the barometer has, with a few slight exceptions, stood abnormally high for the season. North and east winds have prevailed, and very few welcome undercutting winds from the south have appeared. And so, the drought has continued. Fortunately, there are now some signs of improvement.
Anticyclones are not yet very well understood. The International Meteorological Conference has begun a worldwide study of temperature and pressure records which, doubtless, will clear up many difficulties. Meanwhile it seems clear that, in the first place, a shift of a few hundred miles north or south of the axis of the southern anticyclone belt in winter, or of the cores of its subdivisions in summer, makes all the difference in the resulting climatic conditions; giving, e.g., Kimberley in any one year a fall of 31 inches, and in another only 8; giving Aliwal North as much as 39 inches or as little as 11.
A similar phenomenon is known in temperature northern latitudes: a shift of a few hundred miles northward of the summer normal cyclone tracks meaning heavy rain to Scotland, but drought to England.
In the second place, the shifting of the belt, or its parts, is, probably, influenced, for our good or evil, by irregular changes in the state of the Antarctic ice field.
However, let us conclude on a brighter note. Our luck in the weather has been out, and that badly. But in the long run four out of every five seasons are good enough; and the evils of the odd fifth are largely of our own making; due to a pernicious optimism which takes no thought for the future in the light of the past. Overstocking and the ruthless cutting out of the thorn bush are, I am told, rampant everywhere. Hence, when the rains fall, we get no more than we deserve.
The assertion that the country has lost 30 million pounds by one season’s drought really means that farmers have been trying to make too much. Droughts are due to peculiarities of the atmospheric circulation over a whole hemisphere of the earth. They are not to be escaped; and the trumpery quack devices of the rainmaker against them are futile. But is unavoidable the time will come when their approach will be foretold months beforehand. That time will be when our politicians can be got to see that the problems of long-range weather forecasting is infinitely more important than the trifles they like to wrangle about.

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