The importance of the Amazon for regulating the climate in Brazil and the world is recognized and gains prominence whenever events such as the recent floods in Rio Grande do Sul take place, thousands of kilometers away, in the south of the country. Tree evapotranspiration in the biome, for example, allows the formation of rain that is expected every year in different regions of the national territory and even in neighboring countries, favoring other environmental systems, water cycles and farming economies. And in this delicate web of relationships, imbalances in cycles can influence other related events and vice versa. One of the great examples is deforestation: as rates of degradation of green cover advance, humidity in other regions may be affected. In other words: the reduction of the forest exerts direct effect in reducing rainfall.

The so-called flying rivers - air masses loaded with water vapor - help this irrigation system present in the Amazon forest. Located at a height of three to five kilometers away, in the upper atmosphere, these flying rivers transport rains both to tropical regions, with higher temperatures and that need humidity to alleviate the climate, as well as to others that do not belong to the tropics. Wind circulation is responsible for this transport. In parts of the country such as the Center-South, weather systems are powered by these conditions.

Influence

Climatic mechanisms in the equatorial portion of the Pacific Ocean, or some episodes in the Atlantic Ocean, can influence the rhythm of flying rivers. Among them are El Niño and La Niña, phenomena characterized by changes in temperature, which can be from 0.5°C more or less. This occurs due to interference in the atmospheric circulation of winds, affecting the behavior and intensity of rain stores created in the Amazon. Severe droughts in different regions of the world, including in Brazil, are related to the effects of this reality.

Changes affect climate regulation in the Amazon

Another factor that interferes with the regulatory role of the Amazon forest is climate change. According to the United Nations (UN), changes in climate are characterized by long-term alterations in the planet's temperature and climate patterns. Due to anthropogenic actions, gases that cause the greenhouse effect heat the Earth's surface and generate global warming. Research carried out around the world proves that the results of this phenomenon can be related to extreme droughts, water shortages, severe fires, rising sea levels and floods.

All of this started some time ago, with the burning of fossil fuels in industrial processes. In the Amazon, it is deforestation rates that contribute, albeit in part, to climate change. Everaldo de Souza, professor at the Instituto de Geociências da Universidade Federal do Pará – UFPA [Institute of Geosciences at the Federal University of Pará], explains that this relationship occurs due to the passage of CO₂ - carbon dioxide, one of the greenhouse gases – into the atmosphere, since the lack of trees impairs the storage of the chemical compound on the surface. “The dioxide in the atmosphere enhances the effect. This is the contribution of the Amazon.”

Deforestation in the Amazon recorded in the first two months of 2024 was the lowest in the last six years, according to a survey by the Amazon Institute for Man and Environment (Imazon), but it still remains a component of climate change. “To contain the problem, the answer is zero deforestation. The problem is this, it's not just deforestation. The biggest contribution is: industrial processes, burning fossil fuels, oil, etc. So, we have a contribution, but it is even a little smaller than the more intense contribution of industrial processes”, says the professor.

Rio Grande do Sul

Almost 2 million residents of Rio Grande do Sul were affected by the floods that have hit the state for almost a month. Among other reasons, the catastrophe also has to do with the levels of deforestation in the Amazon, as this compromises the forest's ability to regulate the climate, resulting in extreme events. “A hotter planet has a greater capacity to retain water vapor present in clouds. In turn, a planet with more water vapor has more energy available for storms”, explains Souza.

“Then there is a discussion and evidence that it is raining more often in certain regions, there are more extreme events with a lot of rain and it happens associated with floods, flash floods and waterlogging. When the planet is hotter, extreme events associated with greater rainfall, floods and flash floods are more intense. But this is just one aspect, because there is another one, drought events. In some regions, some episodes cause greater rainfall, in other regions, or at another moment of weather variability, the opposite occurs, there is a lack of rain”, adds the UFPA professor.

Future generations will need mitigation measures

Climate change, which greatly affects the regulatory role that the Amazon forest plays for the world, is considered, in some extent, irreversible. Everaldo Souza details that this contribution should be perpetuated for many years to come. “In fact, it was expected that the biggest impacts would be in mid-2050. [But] no. It's already happening now. The biggest effects of climate change are already happening, evident in many corners of the world. Society and the environment, exposed and vulnerable, tend to exacerbate these issues, as it has happened in the South”.

According to the researcher, there are public policies to prevent deforestation and to reverse the energy matrix by avoiding the use of fossil fuels. "All this has to do with issues of mitigating climate change. We will face this problem in the coming years. However, for future generations, so that in the very distant future these problems are not so intense, it makes sense to develop all the policies now. Our climate has changed, there is a new normal of more frequent extreme events and there is no way for us to contain it because it is something that involves global and regional processes”, he adds.

Landfills are challenges for containing climate change in the Amazon

Landfills are storage and decomposition sites for solid waste that produce carbon dioxide (CO₂), methane and nitrous oxide. These gases are the main elements that cause the greenhouse effect, cause climate change and, consequently, alter the water regime in the Amazon. Despite representing 5% of the total of these compounds released into the atmosphere, according to professor Breno Imbiriba, from the Faculty of Meteorology at UFPA, they cause countless damages to society and the environment.

“When there are organic compounds, there is an environment conducive to the formation of bacteria. If they are exposed to oxygen in the air, there are those ones that consume it and emit carbon dioxide, this is the normal breathing of living beings. But at the landfill, it's different. It is made in such a way that the compound is closed, it has no contact with air and the oxygen inside is consumed, with other bacteria beginning to act: methanogenic bacteria, which feed on organic compounds and emit methane. [Thus,] methane goes into the atmosphere and it is a greenhouse gas 28 times more powerful than CO₂”, says Imbiriba.

However, if this issue were better managed, says the professor, landfills would be important help in reducing emissions. “Any reduction is important. Landfill is a direct source of emissions, because you storage organic compound and it degenerates, generating methane gas. Inadequate management or poor construction and non-ideal disposal of organic waste will generate greater gas emissions and this contributes to the total. However, betting all your hopes on building an ideal sanitary landfill is utopian,” he adds.

Population

Poorly constructed landfills in the Amazon, in addition to affecting the climate, also provoke a strong social impact. In the Metropolitan Region of Belém (RMB), this problem is visible among those people who live next to waste storage places. Imbiriba emphasizes that the effects of this pollution are immediate, unlike those involving the climate, which are seen on a long scale. “Sulphide gas and ammonia are emitted from landfills and garbage slurry lagoons. The vast majority of landfills emit carbon dioxide and methane. But it emits other [gases] in smaller quantities, such as odorous gas, which people smell in the neighborhoods, which causes nausea and burns the eyes.”

The studies carried out by the professor include on-site visits to the homes of those who live close to these locations. Analyzes suggest that the population is exposed to a higher concentration of hydrogen sulfide gas than recommended by the World Health Organization (WHO). “People are exposed to odor episodes of random occurrence and random duration, making it difficult for a researcher to observe it. However, in careful, long-term research, it is noticeable that the population is always exposed to these gases, that come at any time of the day and last for short or long periods”, he emphasizes.

The solution involves a more appropriate disposal of waste, according to Breno. “The destination that should have been implemented is selective trash collection, which means separating waste that can be recycled, because this reduces the size of the landfill. If you only collect what is organic, you have one less pile of waste, something easier to manage; 50% of solid waste in Belém is organic”, concludes the professor.