Climate change made historic floods in southern Brazil twice as likely – Study

By the Climate Centre

Climate change made the very extreme rainfall that caused destructive floods in Brazil’s southern state of Rio Grande do Sul in late April and early May twice as likely, according to the latest rapid study from World Weather Attribution group issued yesterday.

The heavy rains were also intensified by the now-fading El Niño phenomenon, while the impacts were made worse by some failures of infrastructure, the WWA scientists add.

The event was “extremely rare” even with global warming – expected no more than once a century – but would have been more rare still without climate change.

By combining observations with climate models, the researchers estimated that climate change made the event more than twice as likely and up to nearly 10 per cent more intense.

‘Natural protection’

Regina Rodrigues, a researcher at the Federal University of Santa Catarina, Florianopolis, who took part in the study, said: “The devastating impact on human systems from such extreme events can only be minimized with sufficient adaptation, including well-maintained flood protection infrastructure and appropriate urban planning.

“Changes in land use have contributed directly to the widespread floods by eliminating natural protection and can exacerbate climate change by increasing emissions.”

The IFRC launched an emergency appeal for 8 million Swiss francs to scale up humanitarian assistance to communities affected by the floods that affected at least 2 million people and were described as the worst disaster in the recorded history of  Rio Grande do Sul state.  

The IFRC global network and the Brazilian Red Cross “will support … 25,000 people who have lost their homes and are in urgent need of assistance, especially single-parent families with children under five, the elderly, and people with disabilities,” the IFRC said last month. 

The latest WWA study was conducted by scientists from Brazil, the Netherlands, Sweden, the UK and the US.

An aerial view of floods in Rio Grande do Sul state from early May. (Photo: Nelson Almeida/AFP via CVB-IFRC)