Frequency Rather Than Intensity Drives Projected Changes of Rainfall Events in Brazil

• Published in: Earth's future 2024-01, Vol.12 (1), p.n/a
• Main Authors: Ballarin, André S., Wendland, Edson, Zaerpour, Masoud, Hatami, Shadi, Meira Neto, Antônio A., Papalexiou, Simon Michael
• Format: Article
• Language: English
• Subjects: Brazil; Climate change; Climate studies; CMIP6; Datasets; extreme events; Extreme weather; Global warming; Natural environment; Parameter estimation; Precipitation; Rainfall; Rainfall distribution; Time series
• ISSN: 2328-4277; 2328-4277
• DOI: 10.1029/2023EF004053

Extreme rainfall events are expected to intensify with global warming, posing significant challenges to both human and natural environments. Despite the importance of such assessments, they are unevenly widespread across the globe. Here, using bias corrected climate simulations of the latest phase of the Coupled Model Intercomparison Project (CMIP6), we provide a comprehensive assessment on how different rainfall events are expected to change across Brazil. Specifically, (a) we explored the projected changes in both intensity and frequency of rainfall events belonging to the right‐tail of the rainfall distribution using a non‐parametric approach, and (b) quantified how rainfall events associate with different return periods are expected to intensify, using a parametric approach. We found that extreme rainfall events will become more frequent and intense by the end of the century, with averaged projected changes for rainfall exceeding the historical rainfall quantile q0.99 of nearly 100% and 10% on frequency and intensity, respectively. Non‐extreme rainfall events, in contrast, are expected to be less frequent, aligning with the compensation hypothesis. For instance, Brazilian 100‐year rainfall are anticipated to intensify, on average, 17% and 31% under the moderate and the highest CMIP6 emission scenarios, respectively. Finally, our findings suggest that frequency, rather than intensity, dictates the projected changes of rainfall. We believe that the evidence gathered here will certainly contribute to not only an improved understanding of Brazilian rainfall events but also to a better comprehension of the different rainfall properties, their interplay and how the different ways of assessing them may affect climate studies. Plain Language Summary The dynamics of rainfall events are expected to change in the future due to global warming. Understanding how this is likely to happen is extremely important for society, since this information is usually required for water resources management and for the design of infrastructure systems. To this end, studies commonly rely on climate models simulations, as they can offer a preview of forthcoming scenarios, helping us to understand the potential effects of such changes to society. Here, using the last generation of climate model projections, we propose an alternative way to explore how rainfall events might change in Brazil. Our results show that heavy rainfall events will be much more frequent and stronger in the