Human-induced climate change made the extreme rainfall that triggered deadly floods in South Africa in April heavier and twice as likely to happen, a rapid analysis published Friday by the World Weather Attribution project shows.
Parts of South Africa experienced more than 350mm of rainfall in two days, causing destructive floods in KwaZulu-Natal and Eastern Cape provinces, killing at least 435 people and damage to property worth around $1.57 billion.
The Port of Durban, Africa’s largest port, was forced to halt operations due to the floods, causing disruptions in supply chains.
“Most people who died in the floods lived in informal settlements, so again we are seeing how climate change disproportionately impacts the most vulnerable people,” said Friederike Otto from the Grantham Institute at Imperial College London, who leads the World Weather Attribution (WWA) project.
“However, the flooding of the Port of Durban, where African minerals and crops are shipped worldwide, is also a reminder that there are no borders for climate impacts,” she said. “What happens in one place can have substantial consequences elsewhere.”
The scientists analyzed weather data and computer simulations to compare today’s climate, which is around 1.2 degrees Celsius warmer than temperatures before industrialization, with the climate of the past.
They also concluded that an extreme rainfall episode such as the one in April could now be expected to happen about once in every 20 years.
“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,” the group said in a statement.
It added that these extreme rainfall events are expected to be 4-8% heavier than in the past.
“If we do not reduce emissions and keep global temperatures below 1.5º C, many extreme weather events will become increasingly destructive,” said the WWA’s Izidine Pinto, from the Climate System Analysis Group at the University of Cape Town. “We need to drastically reduce greenhouse gas emissions and adapt to a new reality where floods and heatwaves are more intense and damaging.”
Scientists have warned that the world must try to cap global warming to 1.5C to stave off some irreversible impacts of climate change.
In southeastern Africa, warming of 2C is projected to bring an increase in the frequency and intensity of heavy rain and flooding, and an increase in the intensity of strong tropical cyclones, which are associated with heavier rainfall.