Rain disasters have tripled in Brazil, report says

From 2020 to 2023, Brazil experienced 7,539 climatic disasters caused by heavy rainfall. The figure shows a surge of 222.8 percent compared to the 1990s, when 2,335 episodes were recorded. These are floods, storms, and landslides that have occurred more frequently and intensely since 2020.

The data come from the report Temporadas das Águas: O Desafio Crescente das Chuvas Extremas (“Seasons of Water: The Growing Challenge of Extreme Rainfall”), the second study in the series Brasil em Transformação (“Brazil in Transformation”), produced by the Brazilian Alliance for Ocean Culture and coordinated by the Federal University of São Paulo (Unifesp).

According to Unifesp researcher Ronaldo Christofoletti, who leads the study team, the results are based on long-term data and cast light on current phenomena.

The figures, he pointed out, also corroborate the projections of the Brazilian Panel on Climate Change, which point to a new trend in the Brazilian rainfall regime, with a 30 percent growth in rainfall in the South and the Southeast and a reduction of up to 40 percent in the North and the Northeast by the end of this century, in 2100.

“We’re starting to see these changes in time and space. In some places it’s going to rain a lot, to the point of causing disasters where it’s often not expected—as we’ve seen, and are seeing again, in Rio Grande do Sul [state], with too much water in too little time. And then we’re going to have regions already receiving little water, like the sertão, which will get even less rain,” he stated.

The document includes details on data from the Ministry of Integration and Regional Development for 1991 through 2023. Over these 32 years, narrowing it down to climatic disasters caused by heavy rainfall, the total number of events is 26,767.

In the period, 64 percent of these disasters were hydrological in nature, with flash floods being the most frequent, accounting for more than half of this percentage (55%), followed by regular floods (35%).

Disasters caused by rainfall of a meteorological nature accounted for 31 percent of the more than 26 thousand incidents during this time frame. Thunderstorms added up to 75 percent of these.

Less frequent, geological disasters accounted for only five percent of the total, of which 91 percent were landslides.

Rio Grande do Sul, southern Brazil –  Marinha do Brasil/RS

Cities

The study also looks at the occurrence of these disasters in Brazilian cities. In total, so far, extreme events linked to rainfall have affected 4,645 cities, representing around 83 percent of Brazil’s municipalities. In the 1990s, no more than 27 percent of them had been affected, and in the first decade of the 2000s, 68 percent had faced some kind of rain disaster.

The rise in these numbers should impact those living in the affected cities in various ways, researchers believe. “We’ll have direct and indirect impacts. As a direct impact of extreme rain and flooding, there may be material losses to homes, infrastructure, impacts on production, displacement of people, and impacts on health care. And then we start to get into a second scenario—the loss of mental health—which we can’t measure directly,” Christofoletti added.

The change in Brazil’s rainfall regime also appears in a study by the country’s water and sanitation authority, ANA, which points to a shrinkage in the availability of water resources—a potential decline of over 40 percent in river basins in the North, the Northeast, the Central-West, and part of the Southeast by 2040.

In Christofoletti’s view, the consequences of these impacts will put pressure on the people in these regions to migrate, leading to new flows of climate refugees.

“Families, whole groups of people will realize they’ll have to move from their territory to a new one, because they can no longer have the life they had—whether it’s because of insecurity, because it’s an area with a lot of flooding, a hillside, or because they depended on family farming, which is now no longer possible in their original location. So the tendency for climate refugees to grow around the world is really strong,” he argued.

Adaptation

Juliana Baladelli Ribeiro, a specialist in nature-based solutions and a member of the research team, described the data as a wake-up call to encourage public managers, the private sector, and social organizations to implement sustainable strategies, especially in urban centers.

Among the complementary strategies, she advocated nature-based solutions, which add resilience and quality of life to cities.

“We’re not saying that nature-based solutions will be the silver bullet, but we understand they are crucial, because it’s a type of technology that uses green infrastructure to solve these problems, bringing multiple additional benefits,” the expert from the Boticário Group Foundation went on to state.

Examples listed by Ribeiro include rain gardens, urban parks, and artificial ponds as part of drainage systems.

“Instead of a concrete pool, if we could have a park, or a pond… Like the Barigui Park, in Curitiba. On a day of heavy rain, the lake fills up, the park floods, and everything is fine, because there’s no structure there that’s going to be severely damaged.”

On days without rain, the park’s infrastructure remains in place, bringing thermal comfort to the city, as well as being an area for leisure and exercise, she mentioned.

Borders

The study, Ronaldo Christofoletti added, in addition to gathering data that will serve to draft the guidelines for the development of more resilient cities and economies, provides insights into the integration of the planet through its different biomes.

“It’s not just about the biome in which I live—whether it’s the Atlantic forest, the Amazon, or the pantanal. The study effectively tells us how important the polar regions, in this case Antarctica, are for Brazil,” he remarked.

The causes of the change in rainfall in some regions of Brazil, he said, are also due to the pressure of global warming in the polar region.

“The change in this rainfall cycle is basically due to higher air temperatures, due to greenhouse gases, plus the variation in the arrival of cold fronts, which regulates rainfall periods—especially in the Southeast, the South, and the Central-West of Brazil,” he concluded saying.