In recent years, weather forecasts have become increasingly effective. The expansion of the database available for analysis, the incorporation of artificial intelligence tools and other technological advances have significantly increased the reliability of weather forecasts — which, of course, are not exercises in futurology, but indicate, on a scientific basis, likely events . Sometimes very likely, as several warnings had already indicated in the case of the extreme storms that hit the north coast of São Paulo last weekend, tragedy that already recorded almost 50 deaths this Thursday (23).
"The models had already persistently indicated, a few days in advance, a high possibility of intense rain during the weekend”, says Cepagri/Cocen meteorologist, Ana Ávila. Why, then, even in the face of such serious warnings, were state and municipal authorities unable to be effective in prevention and communication actions? “I followed the forecast and knew that people were exposing themselves to a very high risk. There is work that we need to do, in all instances, to raise awareness and assertiveness in our alerts. We still don't have this culture of extreme events here in Brazil”, says the meteorologist, adding that, “in other countries, this is different. In the United States, for example, the alerts are very assertive and followed to the letter,” she adds.
In the conversation below, Ana Ávila talks about the relationships between extreme storms and global climate change, the economic issues that involve the dissemination of warnings (in this case, according to G1, the city of São Sebastião avoided publishing warnings so as not to alienate tourists) and the most urgent prevention measures.
Unicamp Portal - Was this the biggest rain ever recorded in 24 hours in the country?
Ana Ávila - This information came from a reliable institution, Cemaden, which works with data from all over Brazil. But, of course, this reflects the time series we have available. Brazil has a very big challenge in data collection in some regions. We have areas quite devoid of information, such as the Amazon region, the cerrado area, the central-west region. So we have some unmeasured areas. Brazil is a country of continental dimensions, with different climates and meteorological phenomena that act at different times, quite intense. This Cemaden data reflects available data. But, in that region, around 300 mm are expected throughout the month of February. That's the average. And we had 680 mm in practically 24 hours. It's a lot of rain.
PU - What explains, from a meteorological point of view, this extreme phenomenon?
Ana Ávila - There were several meteorological phenomena that happened at the same time. We had a very intense cold front that moved from the south of the country and was accompanied by a colder air mass. We had high temperatures in the region — hot, humid air, coming from both the northern Atlantic Ocean and the Amazon region. And the local factors: the Serra do Mar, which blocks the clouds, and the Atlantic Ocean, which on the country's coast is one degree, on average, above normal. It was predicted that this cold front would remain stationary on the coast. And when there was an encounter with these hot and humid air masses coming from the north, intense clouds were formed, which rose quickly. These meteorological phenomena acted together, generating the intense rain that occurred here in the state of São Paulo.
PU - If there was an influence from rising ocean temperatures, is there a clear relationship between the occurrence of the phenomenon and global climate change?
Ana Ávila - With ongoing global climate change, higher temperatures favor the formation of clouds and intense rain, concentrated in short periods. With the ocean warming, there is a potential for more intense clouds to form, that is, greater evaporation. It is worth remembering that cities close to the coast are the areas most at risk, due to warming ocean waters and rising sea levels. And cities, large urban centers, have the greatest risk. The most vulnerable areas are occupations in areas close to hill regions, where landslides occur and the soil is completely soaked. We now see that even trees were carried away.
PU - Why were the warnings not enough to prevent the tragedy, in this case?
Ana Ávila - There are several factors. In this case, even an economic issue. It is a tourist place. So, how do we make people avoid traveling, make the decision not to go to the coast? Let's say you've already made a reservation, suddenly you get an alert saying, "don't go." Will you trust? This is different in other countries. In the United States, for example, it is a very serious thing. The alerts are followed to the letter and are very assertive. In this case, as I followed the forecast, I knew that people were exposing themselves to a very high risk. So, there is work that we need to do in all instances in this sense, raising awareness, asserting our alerts. Here in Brazil, we don't have this culture of extreme events. We are working on it. And the meteorologist can't keep warning about everything either. This is a very big challenge, this issue of assertively issuing the alert.
PU - What are the most urgent measures to prevent phenomena of this type from causing damage and loss of life?
Ana Ávila - There are long-term measures and others that are more immediate, depending on the situation, whether a phenomenon is predictable or not. This one, for example, was predictable. The models had already persistently indicated, a few days in advance, a high possibility of intense rain during the weekend. So, it was a predictable phenomenon, but sometimes it isn't. Sometimes it is a very quick formation, which does not allow for this prediction. Therefore, prevention measures involve very interdisciplinary issues. We need to work on the issue of reliability and assertiveness of alerts. And, once the alert has been issued, decision makers must act according to each municipality, each structure. People need to have knowledge about these phenomena. It is, in the long term, quite intense awareness work. And, more immediately, civil defense actions. The decision maker really needs to know that their way of acting will have a consequence.
PU - How to address the issue of generations of people living in risk areas in the country?
Ana Ávila - From the north to the south of the country, in several cities, there are studies that indicate that there are around 10 million people in risk areas. In the long term, we need to think about the issue of urban planning to remove people from these areas. But, at the same time, there is the situation of immediate risk, which could occur again in any location. In these cases, people need support from public authorities so that they can be moved with all respect and attention, and have somewhere to go. It is necessary to convey security that they are going to a temporary place, but can return. Often, they are people who may have health problems that make it difficult for them to move around, they have pets, so it is necessary to welcome them, not simply say "seek shelter, leave your house". This is work that needs to be done.
Weather radar
Made possible through resources from Agemcamp – the state agency that integrates actions from the 20 municipalities of the Metropolitan Region of Campinas (RMC) – a meteorological radar should begin operating in 2024 at Unicamp. The equipment – which required investments of R$3 million and which is part of the project to create the RMC Meteorological Center – is expected to serve municipalities in the region. The radar will provide data for Civil Defense in policies to prevent and combat floods and floods; monitoring water resources, in addition to supporting research on climate and agriculture.
The Center will also assist in the formulation of policies to prevent and combat extreme events, such as the microexplosions recorded in Campinas seven years ago. On that occasion, a storm felled more than two thousand trees, roofed dozens of houses and directly affected more than 1,5 people. According to official data, the storm caused losses of at least R$30 million.
The Center will operate in an Embrapa Digital room, on the Barão Geraldo campus, where Cepagri already operates.
