The region experienced a year's worth of rain in a period of 10 days.
Human-caused climate change worsened the recent torrential rains and floods which devastated parts of southern Africa, killing more than 100 people and displacing over 300,000, researchers said on 29 January.
A study by the World Weather Attribution, which analysed the recent heavy rainfalls that caused severe flooding in parts of South Africa, Mozambique and Zimbabwe, showed that the region experienced a year's worth of rain in a period of 10 days.
It resulted in widespread damage to housing and infrastructure estimated to run into the millions of dollars, and caused untold human suffering, including the loss of lives.
Many homes and buildings in Mozambique were completely submerged under water, while roads and bridges were swept away in the South African provinces of Limpopo and Mpumalanga and parts of Zimbabwe.
The study was conducted by scientists from across the world using peer-reviewed methods to assess the impact of climate change on severe weather patterns and events.
A once in 50 years occurrence
The data obtained from the recent deluges, the rare magnitude of which occurs roughly once every 50 years, confirmed a “clear move toward more violent downpours”, the study shows.
It was also compounded by the current La Niña weather phenomenon which naturally brings wetter conditions in the southern Africa region but was now operating within a much warmer atmosphere.
“Our analysis clearly shows that our continued burning of fossil fuels is not only increasing the intensity of extreme rainfall, but turning events that would have happened anyway into something much more severe,” says Izidine Pinto, a senior climate researcher at the Royal Netherlands Meteorological Institute.
Pinto, who co-authored the study, says the climate models used struggled to pinpoint exactly how much worse the recent floods were made by climate change, but that a 40 per cent increase in the intensity of the rains would be impossible to explain without human-caused climate change.
“It means what would have already been a serious period of heavy rain has been transformed into a more violent deluge that communities are not equipped to deal with,” he says.
Southern Africa floods were way beyond expectations
The affected regions in southern Africa are no strangers to heavy downpours and flooding, but scientists were alarmed by the magnitude of the recent events.
“This event was a surprise to us because we have experienced the previous ones 25 years ago, which flooded the same areas,” says Bernardino Nhantumbo, a researcher with the Mozambique weather service.
“There are places that have recorded in two to three days the rainfall that was expected for the entire rainy season, so this was very challenging to accommodate in any circumstances.”
According to Nhantumbo, Mozambique is downstream to nine international rivers, so when an event like this happens a lot of damage is expected not only because of the heavy rainfall but also because of the stream flow.
“We forecast well because we have different models, but these are those events that even with a good forecast you cannot hold the damages that are associated,” he says.
The central and southern parts of Mozambique were the hardest hit, with the Gaza provincial capital of Xai-Xai and the nearby town of Chokwe largely submerged under water.
Africa-focused climate models
The researchers have also called for the development of climate models in Africa in order to best understand the dynamics and extent of the impact of climate change in the continent's various regions.
According to Friederike Otto, professor of climate science at the Centre for Environmental Policy at Imperial College in London, the lack of climate models developed in Africa was part of the reason why most models struggled to pinpoint exactly how much worse the recent floods were made by climate change.
"All climate models that we have that are freely available are developed outside of Africa. They are all developed within climate modelling centres in the US, Europe and some in Asia.
“But there is not a single climate model that is developed in Africa. Because of this they are usually designed so that they get the weather best in the regions they are made for, and that is true for all models,” she says.
