30 years ago, Brazil had 7 days with heat waves per year. Today, there are 52


The year isn’t even over yet, but some research already points to something quite alarming. 2023 is the hottest year in 125 thousand yearsand may be the hottest year in our history. And, according to research carried out by the National Institute for Space Research (INPE), here in Brazil alone, the number of days with extreme heat waves rose from 7 to 52 days per year during the last three decades.

The study, requested by the Ministry of Science and Technology (MCTI), and led by Inpe researcher Lincoln Alves, sought to analyze the occurrence of three extreme weather phenomena in Brazil: consecutive dry days, maximum precipitation of 5 days and heat waves.

During the week of November 12th, the country has been facing a strong heat wave. Thermometers in São Paulo reached a maximum of 37.7ºthe highest temperature since 1943. The thermal sensation in places like Rio de Janeiro reached 58.5º during the morning of this Tuesday.

Research has shown that these are not isolated cases. In fact, phenomena like this are becoming commonplace. Analyzing the historical period from 1991 to 2020, researchers observed an increase in the occurrence of these anomalies, mainly heat waves.

A heat wave is defined when the maximum temperature is at least 10% above the threshold of what is considered extreme for a period of at least six consecutive days.

They divided these analyzes into 10-year intervals. In cases of heat waves, an increase in the incidence of these anomalies has been recorded during the last 30 years throughout the national territory, with the exception of the southern region of the country, in addition to the southern portion of the states of São Paulo and Mato Grosso.

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The number of hot days increased successively over the years. During the reference period used for analysis, between 1961 and 1990, the number of days with heat waves was around seven. But that number was rising. Between 1991 and 2000, we had 20 days with heat waves per year.

Graph showing increase in heat waves. Between 1961 and 1990, the number of days with heat waves was seven and increased to 52 days in the period between 2011 and 2020 (Inpe WSDI Anomaly/Reproduction)

Between 2001 and 2010 it reached 40, and from 2011 to 2020 it reached the mark of 52 days a year with heat waves. The number of consecutive dry days rose from 80 to 100 on average, in the central area and Northeast of the country. Regarding the increase in rainfall, the most affected was the South region. The maximum rainfall in 5 days increased from 140mm to 160mm.

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For researcher and study coordinator Lincoln Alves, the latest IPCC report (Intergovernmental Panel on Climate Change) has already warned that climate change is impacting different parts of the world in different ways, including Brazil. “Our analyzes clearly reveal that Brazil is already experiencing these transformations, evidenced by the increase in the frequency and intensity of extreme weather events in several regions since 1961 and which will worsen in the coming decades in proportion to global warming,” he said in a press release.

Furthermore, part of these extreme heat waves in the country are a combination of the climate crisis along with the El Niño phenomenonwhich warms the waters of the Pacific Ocean.

The analyzes were carried out using data from 1,252 weather stations. Of these, at least 642 are manual stations and 610 are automatic. For precipitation analyses, around 11,473 rain gauges were used. Then, these data were compared with data obtained during the reference period.

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The article is in Portuguese

Tags: years Brazil days heat waves year Today



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