South Africa needs to understand local climate change

“We’re already on course for a world that is different to the one experienced by humanity since its evolution,” climate scientist Bob Scholes told the Science Forum on Tuesday.

This month, the world’s leading climate scientists and policy makers met in Paris to hammer out an international agreement in an attempt to constrain global temperature increases by two degrees Celcius above pre-industrial levels.

However, the UK MET office announced last month that average global temperatures had already risen by one degree.

“Over the last 10,000 years, the climate of the world has been remarkably stable…. It became possible to have agriculture, complex civilisations, which obviously led to science,” said Scholes, who has contributed to the United Nations’ Intergovernmental Panel on Climate Change’s (IPCC’s) assessment reports and is a distinguished professor at the University of Witwatersrand’s Global Change and Sustainability Research Institute.

However, “Southern Africa warms up at twice the global rate… Day-time temperatures have increased by half a degree in the last century, but night-time seen a 2.44 degree increase,” he noted.

In the “Change is in the Air” report, launched by the South African Environmental Observation Network on the sidelines of the forum, the authors note that while work has been done in other parts of the world to understand how temperature changes will affect ecosystems, more research is needed to understand what will happen in South Africa.

“South Africa covers less than 1% of the world’s land surface and is home to nearly 10% of the world’s plant species, about 7% of the world’s vertebrates and 5.5% of all known insect diversity,” they write. Industries, such as tourism, and economic livelihoods depend on these ecosystems.

“The effects of warming on species’ ranges are widely reported [in cooler parts of the world, such as the Northern Hemisphere] and many people and policy makers assume that plants and animals will respond in a similar manner across the world.”

However, this is not the case. In a semi-arid country like South Africa, the availability of water is just as important. “It is important to understand that the impacts of global change vary across the world and a local perspective and local information is required to understand changes in our own areas, project their likely outcome, and plan accordingly,” the authors write.

Stellenbosch University scientist Prof Guy Midgley referred to this as an “operating manual for the planet”. Midgley, who returned to science after being involved in the IPCC, said he returned to research because “what you realise [being involved in the IPCC] is that we’re trying to make policy with imperfect science. Someone has to keep doing science. There is still quite a lot of uncertainty about how the world works. We don’t have an operating manual for the planet, and we need one.”

While Scholes said that there is not a hard threshold “when the wheels fall off, the risk [of extreme weather events and natural disasters] goes up”.

However, there are non-negotiable thresholds, he said. These include the melting point of ice – because as temperatures rise, the tundra in the Arctic and Antarctic will melt – and the body temperature of warm-blooded mammals.

“You and I all have body temperatures within fractions of degrees of each other. It is the same for all warm-blooded animals,” Scholes said. “As temperatures rise, we struggle to control our body temperature. Our [human] productivity drops about a quarter for every two-degree increase in temperature. Livestock fail to produce milk and breed.”

But, at the same time, animals and ecosystems are more susceptible to the rate of change, rather than incremental change. If temperatures increase slowly, ecosystems adapt, but … if the climate changes too fast, it runs ahead of them [ecosystems and animals].”

However, this rate of change works both ways. While humans needed to curb emissions to stop an escalation in temperature, “trying to reduce emissions too fast would also cause problems”, Scholes said.

 

  • NOTE: This is part of a series produced for Independent Newspapers’ post-Science Forum supplement.

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