Heat waves: number of days more than doubled in 20 years – 11/13/2023 – Daily Life

To understand how the country’s climate is changing, Inpe (National Institute for Space Research) carried out a study based on data collected over the last 60 years and concluded that the number of days with heat waves has more than doubled in the last two decades. .

Carried out at the request of the Ministry of Science, Technology and Innovation, the survey makes it possible to recognize trends in rainfall series, maximum temperature and three other derived indices that are considered climate extremes: consecutive dry days (CDD), maximum precipitation in five days (RX5day ) and heat waves (WSDI).

Data from 1,252 conventional meteorological stations were considered, 642 manual and 610 automatic stations, to construct the maximum temperature series, and a total of 11,473 rain gauges for precipitation data.

Inpe researchers established 1961 to 1990 as a reference period, and carried out segmented analyzes of what happened to the climate for three periods: 1991-2000, 2001-2010 and 2011-2020.

Between 1991 and 2000, the maximum temperature rose by around 1.5°C. However, it grew by 3°C in some places for the period from 2011 to 2020, especially in the Northeast region and nearby areas.

In the reference period, the average maximum temperature in the Northeast was 30.7°C and gradually rose to 31.2°C in 1991-2000, 31.6°C in 2001-2010 and 32.2°C in 2011-2020.

With the exception of the South region, the southern half of the state of São Paulo and the south of Mato Grosso do Sul, the data indicate that there was a gradual increase in heat wave anomalies over the analyzed periods.

In the reference period, the number of days with heat waves did not exceed seven. For the period from 1991 to 2000 it rose to 20 days; between 2001 and 2010 it reached 40 days; and from 2011 to 2020, the number of days with heat waves reached 52 days.

“This information is the source that we can report as reliable of what is being felt in the day-to-day life of society. We are moving from perceiving to knowing. This is a difference in having this robust source of data”, stated the director of the Department for MCTI Climate and Sustainability, Osvaldo Moraes. “These are relevant data to make climate science support decision-making. We are leaving perception aside to deepen knowledge”, he added.

The study also found a variation in the accumulated rainfall in the Northeast and South regions between 2011 and 2020. While there was a drop in the average precipitation rate, with variations between –10% and –40% from the Northeast to the Southeast and in the central region of Brazil , an increase of between 10% and 30% was observed in the area that covers the states of the South region and part of the states of São Paulo and Mato Grosso do Sul.