"Climate change could lead to provinces like Mpumalanga, Limpopo, the North West, KwaZulu-Natal and even Gauteng becoming malaria zones by 2050," he said in comments to a Cape Town press briefing.

Gauteng contains both the capital Pretoria and commercial hub Johannesburg, which along with Cape Town are among only a handful of African urban centres free from a disease that kills more than a million people a year worldwide, mostly children.

"Too often climate change is regarded as someone else's problem," van Schalkwyk said. "The simple truth ... is that climate change is everyone's problem."

The number of South Africans at "high risk" from malaria will have quadrupled by 2020 due to climate change, van Schalkwyk said, at a cost to South Africa of between 0.1 and 0.2 percent of GDP.

He had no current figure for malaria infection rates.

Global warming would also drive plant and animal species in South Africa to extinction, hitting tourism, while water shortages would hit subsistence agriculture and increase migration to already overpopulated city townships.

"In short, climate change will intensify the effects of poverty though losses of biodiversity, agriculture, health and almost every sector of society," he said. "In a developing country like South Africa, this means that our poorest communities will be worst hit by the impacts of climate change."