Climate change brings higher temperatures and heatwaves

BY 7AM last Thursday, Grant Roebert and his farm workers were already dead on their feet.

Battered by the scorching heat, Roebert, 50, knew there was little prospect of any meaningful work being done on his hydroponic lettuce farm in Port Elizabeth.

“You can’t blame your staff for their lack of productivity because you can’t do anything in this heat,” he says. It was sweltering in Port Elizabeth and turned out to be the hottest day in the city in the past 50 years, reaching its highest recorded temperature of 40.2°C in the afternoon.

The highest was over half a century before, on March 11, 1965 when the mercury topped 40.7°C.

More and more, Roebert, who has farmed all his life, worries about the “weird” weather. “Although our plants are under a shade net, they still wither during days like that. You just hope that by the next morning, you’ll see them sprouting and happy again.

“But the weather down here just isn’t consistent any more and the heat causes all kinds of bacteria. We’re going through a hell of a drought and at least one day every week the temperature goes up in the 30s.”

Niki Milkwood, who runs Milkwood Mushrooms, a wholesaler outfit in Port Elizabeth, shares his concern. “We just don’t pick much on days like last Thursday,” she says. “We try to work before 7am. Everyone downs tools, because you can’t work in conditions like that. All our vegetables are lying flat on the ground.”

“I can make a prediction for you,” offers Professor Francois Engelbrecht, an atmospheric scientist at the Council for Sci- These types of days are highly likely to occur more and more frequently.”

Late last month, in its 2016 assessment of the global climate, the World Meteorological Organisation, singled out South Africa’s heatwaves, noting how 2017 started with an extreme heatwave in the first week of January.

It documented how 2016 had made history with a record global temperature – boosted by the powerful 2015/2016 El Nino event – exceptionally low sea ice and unabated sea level rise and ocean heat, noting how these extreme weather and climate conditions had continued this year.

Research by Engelbrecht and his colleagues at the CSIR has revealed how sub-tropical Africa and southern Africa, are particularly vulnerable to excessive temperature increases from climate change, particularly on the agricultural and biodiversity sectors.“The state of the global climate system has warmed significantly – our research shows that over the same period, the average temperature over southern Africa’s interior has increased by 2°C so that is double the rate of global warming,” he says.

More frequent heatwaves over South Africa will outstrip record maximum temperatures. For years, climate change predictions have shown how the summer rainfall region is likely to become hotter and drier, with regions like the south western Cape, now ravaged by drought, drier and hotter.

But there remains a striking lack of data linking heat stress to mortality. That’s what his colleague, Dr Rebecca Garland, is researching: how heat stress from rising temperatures will affect human health in South Africa.