Heat of 2023 in Brazil surpasses years of stronger El Niño – 12/24/2023 – Environment

Brazil is experiencing a year of record temperatures and the impact of this crisis on cities, crops and human health is largely attributed to El Niño, characterized by the warming of the equatorial Pacific Ocean. Data analysis carried out by Sheet indicates that the current event is strong and that temperatures have never presented such an anomaly in Brazil, but that the world has experienced five more severe El Niños in the last 70 years.

In the strongest El Niño cycles, the average temperature in the country increased by 0.14°C, considering the period from June to September, winter months. In the same period of 2023, when the water in the Pacific registered a rise of 1.2°C, the temperature in Brazil rose 0.8°C, that is, 5.7 times more than what was seen in past years.

The conclusion highlights the role of global warming, linked to the burning of fossil fuels and actions such as deforestation, on temperatures. Anthropogenic action on the climate, according to experts, is altering the behavior and effects of El Niño.

A Sheet carried out the analysis using data from Noaa (United States Oceanic and Atmospheric Agency), which measures the water temperature of the Pacific, and records at Inmet (National Institute of Meteorology) meteorological stations from June to September. To arrive at the temperature variation, months with and without the phenomenon were compared (read more about the methodology at the end of the report).

The strength of El Niño depends on the conjunction of several anomalies in heat, wind and pressure patterns. One of the main parameters considered is the temperature of a specific region of the Pacific, measured by the ONI (Oceanic Niño Index). This index indicates whether the water is 0.5°C below or above the average – technically, there is an El Niño when the three-month moving average is 0.5°C above normal five times in a row.

Several meteorologists have already indicated that this year’s heat is the combination of El Niño and global warming. What’s new is how much climate change deepens El Niño.

“Several scientific studies show that the first layers of the ocean are warming, absorbing this extra heat in the atmosphere”, says Tércio Ambrizzi, doctor in atmospheric sciences and meteorology and professor at USP.

A recent analysis by WWA (World Weather Attribution), a group of scientists that studies climate events, reached similar conclusions about the extreme heat that hit Brazil at the end of winter, raising the average temperature by more than 3°C in some cities.

The study points out that, without global warming, the record heat experienced in winter would be 1.4°C to 4.3°C lower, and that human action has increased the chance of extreme heat in the country by a hundredfold.

El Niño, of course, interferes with thermal patterns, but, without climate change, the heat of August and September would not be as intense, according to the researchers.

This year’s winter was the warmest in history in ten Brazilian capitals, as shown by another analysis by Sheet. Municipalities in the Southeast, Central-West and part of the Northeast experienced a heat wave in November, when thermometers reached 40°C and the thermal sensation jumped to 50°C in places like Rio de Janeiro.

The effects of this El Niño boosted by warming were floods and uninterrupted rain in the South, fires in the Central-West, extreme heat in the Southeast and drought in the North and Northeast.

Terrestrial warming has been altering the planet’s hydrological cycle, so, in periods of El Niño, dry places have even more drought and rainy places, even more rain.

“The anthropic signal in this scenario is the strongest of all”, says physicist Alexandre Araújo Costa, doctor in atmospheric sciences from the State University of Colorado (USA) and professor at the State University of Ceará.

“The last three years have been La Niña [resfriamento do Pacífico] and we started 2023 with it, so the correct thing would be for this to bring global temperatures down a little, but the event only masked global warming.”

According to him, the ocean passes on the extra heat from warming in short ways, like a hurricane, for example, or longer ones, like El Niño.

“But global warming is taking El Niño to another level. It is probably no longer the same. Scientific evidence shows that the canonical El Niño, from weak to moderate, is in extinction”, he states.

Phenomenon is expected to get worse

Although this year’s weather event is strong, it is not yet a super El Niño. From September to November, the ONI was 1.8°C – that is, the water in the Pacific was 1.8°C above average.

On a strength scale, a weak El Niño goes up to 0.9°C; the medium, from 1.4°C; and the strong, from 1.5°C to 2°C. Super El Niño happens when the index reaches 2.5°C or more.

Several statistical models from international climatological authorities indicate that the phenomenon will intensify from this month until February. Two of these projections indicate the possibility of a super El Niño in January and February.

“One point to pay attention to is that in the cycle [de El Niño] Of 1997 and 1998, the hottest year was 1998. In 2015 and 2016, 2016 was worse; 2024 could be hotter, if not, it should stay at the same level”, says Costa.

The recipe, according to him, is no secret: gradually banning fossil fuels through mandatory global treaties. “Hence comes the president of COP28 [Sultan al-Jaber] and says there is no science proving the need to reduce fossil fuels. What do these guys think will happen? Miracle?”, he says, about the UN climate conference held in Dubai until mid-December.

The final text of the conference proposed that countries begin to reduce global consumption of fossil fuels.

Methodology

A Sheet obtained Pacific temperature anomaly data (ONI) on the Noaa website (US National Oceanic and Atmospheric Administration) and the temperature of Brazilian stations on the Inmet website.

Only the months that appeared in all sets of three months of moving averages were considered to be El Niño. Stations with incomplete data for more than five days were excluded from the analysis.

To arrive at the air temperature anomaly in Brazil, the report calculated the average temperature for each month, from June to September, in each season in months without El Niño or La Niña. Then, it evaluated how much the temperature of each month with the presence of El Niño deviated from this average.

Finally, it determined the average temperature deviations of all seasons for each month.