João Biehl and Princeton experts collaborate with World Weather Attribution study

June 6, 2024

Climate Changes and Infrastructure Failures Behind 
Southern Brazil’s Most Destructive Extreme Event Ever

Princeton climate experts and social scientists have collaborated with World Weather Attribution on a comprehensive assessment of the impact of climate change, El Niño, and infrastructure failures on southern Brazil’s most destructive extreme weather event ever. 

The unprecedented 2024 April-May floods in Rio Grande do Sul have affected over 90% of the state, an area equivalent to the UK, displacing 581,638 people and causing 169 deaths, with dozens still missing and millions of households impacted. 

By combining weather observations with results from climate models, the researchers estimated that climate change made the event more than twice as likely and around 6-9% more intense. With further warming, these events will become more frequent and destructive.

The meteorological research team included the Director of the High Meadows Environmental Institute (HMEI) and Knox Taylor Professor of Geosciences Gabriel A. Vecchi and the Associate Research Scholar Wenchang Yang, together with scientists from Imperial College London, Royal Netherlands Meteorological Institute, Federal University of Santa Catarina, and National Institute for Space Research (INPE-Brazil), as well as the organization Royal Cross Red Crescent Climate Centre. 

João Biehl, Susan Dod Brown Professor and Chair of Anthropology, and Academic Research Manager Miquéias Mugge, from PIIRS’s Brazil LAB, collaborated with the vulnerability and exposure aspects of the study.

Map outlining the municipalities impacted by the 2024 RS floods.

Map outlining the municipalities impacted by the 2024 RS floods. Source: OCHA. 2024

The international research team concluded that much of the damage was caused by the failure of critical infrastructure that could not contain the accumulated rainfall. Deforestation and rapid urbanization of cities such as the capital Porto Alegre also contributed to increasing the exposure of the population, particularly historically marginalized communities, and worsening the impacts. 

The World Weather Attribution study has been immediately taken up by Brazil’s major media outlets, such as Folha de S. PauloO GloboValor Econômico and piauí magazine, and is generating timely debate among policymakers and the general public. 

Given the climate change-induced rainfall exacerbation and pre-existing vulnerabilities, the southern Brazilian catastrophic floods “necessitate a comprehensive approach to recovery and adaptation.” The research team concluded that “it is crucial that the recovery and reconstruction in RS is climate-smart, taking into account not only the current but also future climate (risks).” Here, climate-smart also means “generating new job opportunities for the legions of urban and rural poor who lost their livelihoods, small businesses, and employment. This would both help reconstruct the state and deter human capital exodus.”

Read the full story here, Climate change, El Niño and infrastructure failures behind massive floods in southern Brazil.

Canoas on may 5, 2024. Photo by Ricardo Stuckert

Canoas on may 5, 2024. Photo by Ricardo Stuckert