Human-driven climate change is the culprit for Brazil’s floods

According to a recently published article by ClimaMeter, a group of researchers at the French-based Laboratory for Sciences of Climate and Environment (LSCE), the floods in Brazil’s southernmost state, Rio Grande do Sul, can mostly be ascribed to human-driven climate change. 

“The precipitation changes show significant increasing precipitation in Rio Grande do Sul state with the Porto Alegre [the state’s capital] area experiencing (3-6 mm/day) up to 15 percent more precipitation in the present than in the past”, the researchers wrote. 

Additionally, “changes in urban areas reveal that Porto Alegre, Caxias do Sul, and São Leopoldo are up to 6 mm/day wetter (up to 15 percent more precipitation) in the present compared to the past.”

The researchers saw no significant change in the impacts of the current El Niño episode in the present compared to the past. “This suggests that the changes we see in the event compared to the past may be due to human-driven climate change, with a minor contribution from natural variability,” they conclude.

The researchers added that changes in rainfall patterns have been observed in different parts of Brazil over the past century, leading to impacts on agriculture.

As The Brazilian Report showed back in January, lower-than-average rainfall since 2012 has been dragging down the Brazilian economy, according to a preliminary study by Bráulio Borges, a senior economist at consulting firm LCA. His study was the first to analyze a correlation between rainfall and GDP in Brazil.

Brazil has had below-average rainfall every year since 2012, Mr. Borges found, with the exception of 2013. On more than one occasion, politicians have considered the possibility of rationing water or electricity, most notably in 2014 and 2021.

The mere possibility of rationing is negative for the economy, Mr. Borges argues, because the government buys more thermal power, which is more expensive (and also more polluting), in order to conserve water, and companies postpone or shelve investment plans.

Less rain also hurts agriculture, a huge part of Brazil’s GDP. Currently, only about 5 percent of cropland is irrigated, compared with 15 percent in the U.S.

Per the LSCE researchers, changes in precipitation and extreme temperatures are impacting agricultural production in Brazil, “with increasing mean precipitation positively impacting agriculture in some areas but extremely long dry spells affecting economies” in the country’s Southeast.

The Porto Alegre City Hall on Monday afternoon reiterated a request for people not to return home, as the Guaíba River levels continue to increase. The river level reached 5.19 meters early on Tuesday morning. The Lami neighborhood, where water has overtaken houses with strong waves, was evacuated during the night.

Per state authorities, more than 2.1 million people have been affected by the ongoing Rio Grande do Sul crisis as of Tuesday. 147 people died, and 125 others are missing. Over 538,000 residents have been displaced, and 76,000 are in shelters.

A survey by Quaest shows that 99 percent of Brazilians believe that the environmental catastrophe that has hit the state of Rio Grande do Sul is linked to climate change — echoing the opinions of the scientific community.

While 64 percent of people blame climate change entirely for the floods and torrential rainfall currently chastising Brazil’s southernmost state, another 30 percent see partial causality — while 5 percent see little connection between the two. Only 1 percent say there is no connection at all between the floods and climate change.

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