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24 Sep 2015 00:00
Dry, dry: Maize field in Ventersdorp. Grain SA says this is the worst drought in 20 years to hit the agricultural sector. (Photo: Simone Kley/Gallo Images)
Soaring temperatures and below-average rainfall are likely to be features of the coming South African summer as the strongest El Nino event in decades climbs towards a peak.
Temperatures over large parts of the country “could be as much as two degrees [Celcius] higher than average this summer”, says Council for Scientific and Industrial Research (CSIR) meteorologist Willem Landman. “There is a reasonable chance we could be heading for the hottest summer on record.”
Conversely, rainfall is likely to be well below average, posing a threat to especially subsistence and smallholder farmers who rely on summer rain to water their crops.
“Rainfall across the summer rainfall regions of South Africa — over the three-month period [of] December to February — could be between 50mm and 150mm below average,” says Landman.
He says while it was possible that these forecasts are not entirely accurate, the data suggests the El Nino is going to become “very strong” indeed.
According to the World Meteoro–logical Organisation (WMO), the United Nations inter-governmental agency tasked with keeping an eye on global climate trends, “the majority of international climate outlook models suggest the 2015/16 El Nino is likely to strengthen further before the end of the year”.
In its latest El Nino/La Nina update, issued earlier this month, the WMO says the El Nino is likely to peak between October this year and January next year.
“Impacts from this El Nino are already evident in some regions and will be more apparent for at least the next four to eight months,” it says.
South Africa is experiencing severe drought in several areas, with KwaZulu-Natal and the Free State hit the hardest.
Reports state the sugar cane and maize sectors in these regions have already lost billions of rands in lost or stunted crops. Stock farmers are also suffering, and water restrictions are in place in some of the affected areas.
The main concern, however, is not for the commercial farming sector. According to Statistics SA, there are close to three million subsistence households in South Africa, in the rural areas of the Eastern Cape, KwaZulu-Natal and Limpopo. Such households typically comprise small-scale farmers who grow just enough crops, or raise enough livestock, for their own consumption, with sometimes a little surplus left for sale.
Landman says these farmers — who do not usually have a stored water supply for irrigating their crops or watering their stock, but rely primarily on rain and local stream flows — are going to be particularly hard hit by the below-average rainfall. “Those people depending on subsistence crops could be in big trouble.”
If subsistence households comprise just four people each, there could be over 10 million rural dwellers facing a serious food shortage in many parts of South Africa early next year.
Landman said the El Nino would have an even stronger impact on South Africa’s northern neighbours — Zambia and Zimbabwe — where there are more subsistence farmers.
El Nino is the term used to describe the warming phase of periodic but irregular changes in climate caused by variations in Pacific surface temperatures, known as the El Nino Southern Oscillation (Enso). The cooling phase is known as La Nina. Enso affects weather patterns across large parts of the globe. Scientists believe sea surface temperatures in the Indian Ocean could also rise as much as two degrees Celcius this summer, affecting weather patterns across the African sub-continent.
Dr Chris Lennard, a research officer for the University of Cape Town’s Climate System Analysis Group, says the effect of the current El Nino is being exacerbated by the high levels of greenhouse gasses in the atmosphere.
“Since the big El Nino of 1998, we have experienced predominantly neutral and La Nina Enso conditions, punctuated by weak El Ninos, with the exception of 2009/10, which was a stronger one.”
These generally “colder than normal” sea surface temperatures meant that the equatorial Pacific Ocean, which covers about a third of the Earth’s surface, had absorbed heat from the atmosphere more efficiently. “This is the likely cause of the slow down in the global temperature increase over the past 12 to 15 years. Now that we are entering a prolonged El Nino state, less atmospheric heat can be absorbed by the ocean, so it stays in the atmosphere.”
Lennard said the United Kingdom’s Met Office was predicting global air temperatures this year would be the hottest on record, with next year’s likely to eclipse these.
One piece of good news is the current El Nino will likely be over by the middle of next year at the latest. According to the WMO update: “[El Nino events] typically decline and then dissipate during the first and second quarters of the year.”
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