Is Karoo hail due to global warming?

An increase in the number of freak weather patterns across the world has researchers scrambling for answers.
Issue date : 13 June 2008

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An increase in the number of freak weather patterns across the world has researchers scrambling for answers. T he Mid-West region in the US has recently been swept by tornadoes, with 17 tornadoes and 200mm of rain recorded in one day in certain areas of Kansas.

In South Africa there was a huge hailstorm 10km outside Ashkam in the arid Northern Cape. The hail is said to have been 6cm thick on the soil surface, and to have looked almost like snow. rthur Chapman, a researcher with the Council for Scientific and Industrial Research (CSIR), said that it’s difficult to determine if these weather phenomena are due to global warming.

“Understanding how the frequency of tornadoes and hailstorms might pan out with increased global warming is problematic, because the current climatic models can’t simulate small-scale weather phenomena such as tornadoes and hail storms,” he said. heoretically, it’s expected that storms will become more violent and that more hailstorms and tornadoes will occur because as the atmosphere warms, it retains more latent heat in the form of water vapour.

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The absence of measuring equipment, however, makes it difficult to ascribe current phenomena to global warming. Chapman pointed out that current data on tornado trends is rather unreliable. Most tornado touch-downs occur over only a few kilometres, and many of them are weak or go undetected. programme of increased observation would likely increase the number of tornado events being recorded – leading to an apparent increase in frequency.

Chapman added that hailstorms occur wherever storms of sufficiently energetic up-and-down drafts can form. Usually, air is heated over large land masses, where the warm landscape creates the convection necessary for hail formation.

Hailstorms are surprisingly frequent even in the semi-desert regions of the world and occur from New Mexico to the Kalahari, to the Arabian Peninsula, to the Negev Desert and indeed all over large landmasses across the world. Chapman added that there seems to be a rise in the financial and social costs of the damage done by tornadoes and hailstorms, but he ascribed this to increased development and population growth. – Glenneis Erasmus

Central Karoo drought: new skeletons every day

The drought in the central Karoo has reached critical proportions. Large numbers of game and livestock are starving and lambs die at birth because ewes simply don’t produce milk. n the past three years, the grip of the drought was worst felt in the Merweville area and it prompted farmers throughout the Western Cape to send emergency supplies of enriched and raw fodder to the Karoo to assist fellow farmers.

Recently, Heidelberg farmers sent 50t of fodder worth about R90 000 to Merweville. This follows an earlier donation, also from the Heidelberg farming community. Farmers at Uniondale are currently collecting both enriched and raw fodder to ship to Merweville. ntonie Botes, the chairperson of the Merweville Farmers’ Union, has described the drought conditions as critical.

He said that few farmers had received additional lambs this season. Only nine of the 90 springbok in his game camp two years ago have survived. The skeletons of sheep are strewn among the bushes and more sheep die every day. “We’re very grateful for the donations reaching us,” he said. “donation from the Heidelberg farmers will keep us going for at least another fortnight.” – Staff reporter

Rain is desperately needed in the Overberg

While Swartland farmers are happy with the rain that has coincided with their winter planting season, dry conditions in the Overberg region could have a negative impact on oats, canola and wheat crops. Since the start of the winter rain season, only 30mm has been recorded in the Strandveld region and the Rûens region has had no rain to date. Orton King, chief executive officer of the Overberg District Agricultural Association, said oats and canola were planted early in the season and dry soil during planting, without subsequent rain, has resulted in poor seed germination.

 Wheat that was planted later is showing the same levels of poor germination. “Farmers are positive by definition, or you have to be, anyway,” said Richard Krige from Boontjieskraal Estate outside Caledon. “Conditions aren’t ideal at the moment and crop losses have already occurred. If there’s no rain by mid-June it will be disastrous.

 A shortage of animal feed is already a crisis and will remain so at least until August.” Farmers in the Overberg region have planted more hectares this year, in response to high grain prices and in spite of soaring input costs, but the right amount of rain is needed now, noted King. – Wouter Kriel

Summer crop forecasts

South Africa can expect an 11,33 million ton maize harvest this year, according to the Crop Estimates Committee (CEC’s) fourth production forecast for summer crops. White maize is expected to yield 6,69 million tons, 2,6% higher than the previous forecast, while yellow maize is predicted to be 4,63 million tons (+3,59%). ccording to the CEC, the maize crop could be slightly higher than predicted depending on what happens in the June forecast, by which time 30% to 50% of the crop will have been harvested. P roduction of sunflower seed is forecast to be 837 710t (+6,60%), while soya beans, groundnuts and sorghum are predicted at 319 495t (+5,71%), 85 360t (+3,86%) and 270 455t (+5,65%) respectively. The production forecast for dry beans remained unchanged from the previous forecast of 58 975t. – David Steynberg