Heat: Summer should break records in Brazil – 09/20/2023 – Daily

The combination of the record heat in the oceans recorded in August with the likely continuation of El Niño until March 2024 points to a summer with unprecedented highs in Brazil.

But warm weather doesn’t take until the start of the season on December 22 to arrive in the country. In addition to heat waves that began in this last week of winter, meteorological forecasts, such as those from Inmet (National Institute of Meteorology), indicate that temperature records could be recorded in spring.

Furthermore, experts say that the rains that hit the South should gain strength with El Niño, especially in December, which will also bring hotter and drier weather to the North and Northeast. Uncertainty falls on the Southeast, with no clear signs of more or less rain and heat.

There is a possibility, however, that Brazil and the rest of South America will record temperatures above historical averages in the summer. In the country, this increase can be registered from São Paulo towards the north.

“All seasonal climate forecast models that look at spring and summer indicate a 70% chance that temperatures will be above average,” says climatologist Francisco Aquino, head of the geography department at the Federal University of Rio Grande do Sul.

“From October onwards, until February 2024, in Brazil, we will see above-average temperatures and below-average precipitation, with the exception of the South. And we have already had the hottest August in history in South America since 1910.”

He cites data published this Tuesday (19) by the US National Oceanic and Atmospheric Administration (NOAA), which consider temperature anomalies in relation to the August averages of each year.

The anomaly is a variation —positive or negative— of a temperature in relation to the baseline. According to NOAA, this line is an average of 30 years or more of temperature data.

According to Inmet meteorologist Adriana Ramos, the institute’s weather forecasts extend until spring — with a tendency towards more heat. “The climate forecast we have is from September to November, and indicates that temperatures should be above average. We don’t have summer yet, but we know that El Niño will act, with a peak from December to January.”

Rainfall is also expected to increase in the South, according to a technical note from Cemaden (National Center for Natural Disaster Monitoring and Alerts). According to the agency, cold fronts tend to remain stationary in the region.

“In general, El Niño favors the action of frontal systems in the South of Brazil. How much these systems will spread further to the Southeast is not so clear”, says meteorologist and advisor to Crea-SP Carlos Raupp. He points out that spring traditionally concentrates the maximum temperatures.

For Paulo Artaxo, physicist and professor at USP, there is a degree of unpredictability in phenomena such as El Niño, especially due to the impacts of global warming. “It’s a complex system and we’ve never had a strong El Niño like this year, coupled with worsening global climate change.”

The last formation of the phenomenon was between 2015 and 2016, which was characterized as a super El Niño. Now, warmer oceans, according to the record recorded in August, are expected to accentuate their effects. “This is because El Niño is exactly produced by an abnormal warming of the tropical Pacific Ocean.”

As these waters heat up, there are changes in the circulation of the trade winds, which go from east to west, carrying moisture and warmer waters from the coast of the Americas to Asia and Oceania. The effects cause droughts and floods in different parts of the world.

On the other hand, according to Aquino, the phenomenon will encounter warmer waters. The increase in temperature caused by the emission of greenhouse gases is slowly absorbed by the oceans. “During human global warming, the atmosphere and ocean, we stored most of the warming in the ocean, which has more mass.”

It is in this scenario of warmed waters that the effect of El Niño can increase temperatures above average. “It is a large area of ​​hot water in the Pacific that will disturb the planet’s tropical atmosphere. The entire circulation, for two hemispheres, will adapt to this signal coming from the ‘hot water pool’ in the tropical Pacific”, states the researcher.

According to Aquino, the phenomenon, a natural and historical variability in the warming of the Pacific near the Equator, and the change in wind circulation act as a signal.

“The atmosphere understands ‘we will adjust’. But what happened in the last hundred years? These events, from the 1960s to now, have become more intense because the ocean has become warmer.”