Summary/Abstract
Record-breaking rainfall in the Rio Grande do Sul province of Brazil led to extensive flooding in late April and early May 2024. This was one of the most significant environmental tragedies experienced in Brazil, affecting 90% of the state’s municipalities. In this real-time event study, researchers used peer-reviewed climate models to assess the impact of human-induced climate change and the El Niño Southern Oscillation (ENSO) on the likelihood and intensity of the rainfall that caused the flooding.
The authors found that ENSO played a relatively large role in the flooding, increasing the likelihood and intensity of such rainfall significantly – by a factor of 2-3 in likelihood and 4-8% in intensity for the 10-day rainfall event, and a factor of 2-5 in likelihood and 3-10% in intensity for the 4-day event. The authors also assessed the role of human-induced climate change, and found comparable impacts – over both periods, human-induced climate change increased the likelihood of such an event by more than a factor of 2 and the intensity by 6-9%.