Climate change increased heavy rainfall, hitting vulnerable communities in Eastern Northeast Brazil

The report investigates the May 2022 extreme rainfall event in Eastern Northeast Brazil, which caused 133 deaths and displaced over 25,000 people. Observational analysis indicates that 7-day and 15-day rainfall events of this magnitude are exceptionally rare in the current climate, with return periods of approximately 1-in-500 and 1-in-1000 years, respectively. While climate models exhibited systematic errors in precipitation magnitudes for this specific event, the authors conclude that human-caused climate change is at least partially responsible for increasing the likelihood and intensity of such rainfall. The study further highlights that structural vulnerabilities, including unplanned urbanisation in low-income neighbourhoods and an infrastructure deficit, significantly exacerbated the disaster's impact.

• The extreme rainfall event in May 2022 was exceptionally rare in the current climate, which has warmed by approximately 1.2°C due to human activities. The 7-day mean rainfall event had a return period of approximately 1-in-500 years, while the 15-day mean rainfall event had a return period of approximately 1-in-1000 years.
• Human-caused climate change has increased the intensity of rainfall in the region. Rainfall events of this rarity would have been approximately 20% less intense in a climate that was 1.2°C cooler.
• Climate models were unable to quantify the specific role of climate change in the observed increase in likelihood and intensity because they exhibited systematic errors in precipitation magnitudes for this spatially small event, partly due to coarse spatial resolution and poor representation of convection.
• Despite model limitations, the authors conclude that human-induced climate change contributed to the increased likelihood and intensity of the heavy rainfall observed in May 2022, a trend expected to continue as greenhouse gas concentrations rise.
• The disaster's impact was disproportionately severe for vulnerable communities, particularly in low-income neighbourhoods, due to pre-existing structural vulnerabilities and unplanned urbanisation on steep hillsides and in low-lying flood-prone areas.
• The event resulted in 133 fatalities and the displacement of over 25,000 people, with at least 80 municipalities in Alagoas and Pernambuco declaring states of emergency.
• There is a critical need to improve the connection between weather warnings and anticipatory actions, as well as to update infrastructure design standards to account for increasing climate risks.

APA

Zachariah, M., Junior, F. D. C. V., Silva, T. L. D. V., dos Santos, E. P., Coelho, C. A. D. S., Alves, L. M., Martins, E. S. P. R., Köberle, A. C., Singh, R., Vahlberg, M., Marchezini, V., Heinrich, D., Thalheimer, L., Raju, E., Koren, G., Philip, S., Kew, S., Bonnet, R., Li, S., ... Otto, F. E. L. (n.d.). Climate change increased heavy rainfall, hitting vulnerable communities in Eastern Northeast Brazil. World Weather Attribution. https://www.worldweatherattribution.org/wp-content/uploads/Brazil-Floods-Scientific-report.pdf

Chicago

Zachariah, Mariam, Francisco das Chagas Vasconcelos Junior, Thiago Luiz do Vale Silva, Edvânia Pereira dos Santos, Caio Augusto dos Santos Coelho, Lincoln Muniz Alves, Eduardo Sávio Passos Rodrigues Martins, et al. Climate change increased heavy rainfall, hitting vulnerable communities in Eastern Northeast Brazil. World Weather Attribution, n.d. https://www.worldweatherattribution.org/wp-content/uploads/Brazil-Floods-Scientific-report.pdf.

Wikipedia

{{cite report |last1=Zachariah |first1=Mariam |last2=Junior |first2=Francisco das Chagas Vasconcelos |last3=Silva |first3=Thiago Luiz do Vale |last4=dos Santos |first4=Edvânia Pereira |last5=Coelho |first5=Caio Augusto dos Santos |last6=Alves |first6=Lincoln Muniz |last7=Martins |first7=Eduardo Sávio Passos Rodrigues |last8=Köberle |first8=Alexandre C. |last9=Singh |first9=Roop |display-authors=etal |title=Climate change increased heavy rainfall, hitting vulnerable communities in Eastern Northeast Brazil |publisher=World Weather Attribution |url=https://www.worldweatherattribution.org/wp-content/uploads/Brazil-Floods-Scientific-report.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{zachariahndclimate, author = {Zachariah, Mariam and Junior, Francisco das Chagas Vasconcelos and Silva, Thiago Luiz do Vale and dos Santos, Edvânia Pereira and Coelho, Caio Augusto dos Santos and Alves, Lincoln Muniz and Martins, Eduardo Sávio Passos Rodrigues and Köberle, Alexandre C. and Singh, Roop and Vahlberg, Maja and Marchezini, Victor and Heinrich, Dorothy and Thalheimer, Lisa and Raju, Emmanuel and Koren, Gerbrand and Philip, Sjoukje and Kew, Sarah and Bonnet, Rémy and Li, Sihan and Yang, Wenchang and Sun, Jingru and Vecchi, Gabriel and Otto, Friederike E. L.}, title = {{Climate change increased heavy rainfall, hitting vulnerable communities in Eastern Northeast Brazil}}, institution = {World Weather Attribution}, url = {https://www.worldweatherattribution.org/wp-content/uploads/Brazil-Floods-Scientific-report.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }