Data collected at 271 meteorological stations across Brazil show that temperature and heavy rains have increased in recent decades, according to a study by Inmet (National Institute of Meteorology).
The survey of the body is in the document “Normais Climatológicas do Brasil 1991-2020”. Normals are historical averages of temperature, humidity, precipitation, humidity and wind, for example.
In the document, which will be published in its entirety this Wednesday (23), Inmet states that the rise in temperature recorded in recent years may be related to natural variability and global warming. These climate changes, says Inmet, have the “most likely cause” of human actions.
According to the IPCC (UN Intergovernmental Panel on Climate Change), the human influence on global warming is already clear.
Inmet compared, for example, the normal values collected between 1931 and 2020 on the minimum air temperature in São Paulo (SP). The data show an increase in all months of the year, comparing the period between 1931-1960 and 1991-2020.
“The early mornings are getting hotter in São Paulo-SP. The elevation is greater than 1.6°C in all months of the year, especially in the months of July and April, with a minimum temperature rise of 2.7 °C”, says the document.
When comparing the periods 1991-2020 with 1961-1990, it is also possible to observe an increase in the minimum temperature, however, the highest increase was lower, 1.2°C. The month of April of those years registered the biggest increase.
The increase in temperature was also captured by the stations in Brasília (DF). According to the monitoring, “average temperatures rose in all months of the year and, specifically in the month of October, the increase is 1.5°C when compared to the periods of 1961-1990 and 1991-2020”.
In Fortaleza (CE), the comparison between the normals of 1961-1990, 1981-2010 and the most recent period of 1991-2020 shows an increase in the maximum temperature over the years in all months.
If the last two analyzed periods are compared, the days are getting hotter and there are peaks in the months of August and September, with an elevation of 1.2°C.
The records of extreme rains, as well as those that have already killed more than 230 people in Petrópolis (RJ), also increased, according to Inmet, with a greater number of storms with a volume of 80 mm and 100 mm.
Data analysis also suggests a change in the rainfall pattern in certain regions. One of these cases of change occurred in Maceió (AL).
The data for the periods 1931-1960 and 1961-1990 show higher with the month with the highest precipitation. and may. In later periods, however, the wettest month was June.
Barcelos, a city in the north of Amazonas, also registered a change in the wettest month, before it was May and now it’s April. In the four-month period with the highest rainfall, for example, the average rainfall increased by an average of 244.5 mm, when comparing the periods 1931-1960 and 1991-2020.
In October, the rain fell by 21.0 mm when compared to the same periods.
In São Paulo (SP), the study points not only to an increase in almost every month of the year, but also to the increasing record of storms with volumes above 50, 80 and 100 millimeters between 1961 and 2020.
“Comparing the periods 1931-1960 and 1991-2020, it is observed that there was an increase in precipitation in all months of the year, with the exception of August, which showed a slight decline of 6.5 mm. In March and December the highest elevations in total precipitation were observed, with 56.1 mm and 51.1 mm, respectively,” says the study.
If comparing the data from the last decade (2011-2020) with the period 1991-2000, the number of days with rain above 50 mm decreased, but the storm records above 80 and 100 mm increased —9 to 16 days and 2 to 7 days, respectively.
“In other words, extreme events of excessive rain in the city of São Paulo have increased since the beginning of the 1990s. The change in the rainfall pattern is even more evident when comparing the last decade with the initial period of analysis (1961-1970) “, says Inmet.
According to Inmet, studies on climatological normals serve to, in addition to recording climate changes, guide, inform and assist the scientific community, agribusiness and public and private institutions.
One of the practical applications, says the document, is to define the agroclimatic zoning that makes it possible to identify the crops to be implemented in each region based on climate risk.
“Updating and monitoring weather conditions are extremely important for agribusiness, agricultural insurance climate risk, the financial market, the energy generation sector, among others,” says Inmet.
In its final considerations, the study also cites the IPCC report that points to the widespread and serious losses and damages to human and natural systems caused by human-induced climate change.
According to the report, extremes are “overcoming the resilience of some ecosystems and human systems, and challenging the adaptive capacities of others, including impacts with irreversible consequences.”
“Vulnerable people and human systems and climate-sensitive species and ecosystems are most at risk,” the text reads.
