Climate change made deadly SA rains ‘twice as likely’

RAINFALL that caused catastrophic floods and landslides last month in and around Durban was made twice as likely by global warming, scientists claimed on Friday.

An exceptional downpour – more than 35cm over two days – on April 11-12 claimed hundreds of lives and caused R24.3 billion in damage across the provinces of KwaZulu-Natal and Eastern Cape.

Without climate change, rain of this intensity would happen roughly once every 40 years, according to a report from the World Weather Attribution consortium (WWA), a global network of scientists that attempts to quantify the impact of a warming world on extreme weather events.

But an increase in Earth’s average surface temperature of nearly 1.2°C since the late 19th century has allegedly shortened that interval to about 20 years.

“The probability of an event such as the rainfall that resulted in this disaster has approximately doubled due to human-induced climate change,” the scientists claimed in a statement.

If the planet continues to heat in coming decades, the frequency and intensity of devastating floods caused by these downpours will increase, they warned.

They said the same was true for heatwaves, droughts, tropical cyclones – also known as hurricanes or typhoons – and wildfires.

Most of the world’s nations have embraced a target of capping global warming at 1.5°C, but current greenhouse gas reduction commitments would see temperatures rise far higher.

In the case of heavy rains, every extra degree of global warming could increase the amount of water in the atmosphere by about 7%.

But only recently has an accumulation of climate data and more sophisticated tools made it possible to attempt to answer the most obvious of questions: to what extent is a particular weather disaster caused by global warming?

The heatwave, for example, that gripped western North America last June, sending temperatures in Canada to a record 49.6°C, would have been “virtually impossible” without human-induced climate change, the WWA said.

And record-setting rainfall and flooding last July in Germany and Belgium that left more than 200 dead up was allegedly made up to nine times more likely.

Friederike Otto, lead author of the South Africa assessment, said the destruction was a result not just rainfall intensity, but the exposure of human populations.

“Most people who died in the floods lived in informal settlements,” said Otto, a scientist at Imperial College London’s Grantham Institute and a pioneer in the burgeoning field of event attribution studies.

“So, again, we are seeing how climate change disproportionately impacts the most vulnerable people.”

The WWA is currently assessing the unprecedented heatwave that scorched large swathes of India and Pakistan during March and April. |