Cape Town - The extreme weather events surrounding the deadly flooding in KwaZulu-Natal had not only scientists, but the general public, curious about how exactly the severe rainfall was able to cause the extent of destruction it did and what role climate change played.
Now a new study by the World Weather Attribution (WWA) project has the answers.
The WWA project is an international collaboration that analyses the possible influence of climate change on extreme weather events. Its new study, “Climate change exacerbated rainfall causing devastating flooding in Eastern South Africa”, was conducted by a team of more than 15 climate scientists from South Africa, France, the Netherlands, the UK and the US.
The study revealed that climate change made the deadly flooding in KZN more severe and that the probability of such an event doubled due to human-induced climate change.
The scientists urged cities to better prepare to deal with extreme weather events as they would be occurring with increased frequency – particularly in South Africa and its neighbouring countries, which were especially vulnerable to the effects of climate change.
UCT African Climate and Development Initiative senior research fellow Christopher Trisos said: “Africa’s rapidly growing cities will be climate change hotspots, which will amplify pre-existing stresses related to poverty, social and economic exclusion, and governance. These challenges are often greatest for people living in informal settlements.”
Trisos said it was urgent that African cities acted now to adapt to climate change risks through good governance, adequate financial support for adaptation, and adopting ecosystem-based approaches to adaptation.
To evaluate the role of climate change on the chances (and intensity) of this extreme rainfall happening, the WWA group analysed weather data and computer simulations to compare the climate as it is today, after about 1.2°C of global warming since the late 1800s, with the climate of the past, following peer-reviewed methods.
“Without human-caused global warming such an event would only happen once every 40 years, so it has become about twice as common as a result of greenhouse gas emissions.
“This means a heavy rainfall event that can now be expected about once every 20 years is about 4-8% heavier than it would have been without climate change,” the WWA group said.
UCT Climate System Analysis Group climatologist Izidine Pinto said if emissions were not reduced and global temperatures exceeded 1.5ºC, many extreme weather events would become increasingly destructive.
“We need to drastically reduce greenhouse gas emissions and adapt to a new reality where floods and heat waves are more intense and damaging,” Pinto said.
A previous WWA study found that the 2018 drought in Cape Town and surrounds was three times more likely because of climate change; Nelson Mandela Bay now faces a “day zero”.