This includes using observational data and two sets of computer simulations, one that models the world as it is, about 2 degrees Fahrenheit (1.1 degrees Celsius) warmer than it is. was before widespread emissions began in the late 19th century, and a hypothetical world in which global warming never occurred.
The conclusion that the likelihood of such an extreme rain event has increased with global warming is consistent with many other studies of individual events and larger trends. One of the main reasons for this increase is that as the atmosphere warms, it can hold more moisture.
The study noted that from a meteorological perspective, a storm that has a 1 in 20 chance of occurring in a given year, although not common, is not a rare event. The researchers therefore looked at other factors that could have contributed to the high death toll and damage caused by the disaster.
Among these, they wrote, were the legacies of policies instituted during the apartheid era. In 1958, for example, Durban City Council passed a measure that forced non-whites to settle in areas that were less desirable and, in many cases, more prone to flooding.
The researchers also cited the rise of makeshift settlements due to rapid urban growth and lack of affordable housing. About 22% of Durban’s population, or 800,000 people, live in such settlements, which generally lack proper services and infrastructure. During the April floods, the study noted that about 4,000 of the 13,500 homes that were damaged or destroyed were along riverbanks in these types of settlements, and most deaths also occurred in these areas.
“Once again we see how climate change disproportionately affects the most vulnerable people,” said Friederike Otto, founder of World Weather Attribution and a climatologist at Imperial College London.