Amazon: The Heart of Mother Earth
Patricia Sánchez Carrillo
Introduction
The Amazon is home to the largest tropical forest in the world and as such is the largest source of life on our planet. The complex functioning of its ecosystem plays a critical role in balancing the global climate, as its millions of trees absorb carbon dioxide and release oxygen into the atmosphere. It is, therefore, a key element in the regulation of the carbon cycle and the indiscriminate felling of its trees directly affects climate change.
The rivers that make up the Amazon river network constitute the largest freshwater reserve on Earth. This vast watershed, along with the immense vegetation of the tropical forest, makes up what is commonly referred to as “the lungs of the world”. In addition, the Amazon is also considered the “heart of mother earth”, as it can ‘pump’ moisture and transport water to the interior of the continent, far beyond the Andes mountain range. This phenomenon does not occur through terrestrial rivers as one might expect, so how is it possible to transport water over such a long distance if not by the surface?
Some Generalities of the Amazon
The Amazon is home to the largest rainforest on the planet. Its rivers discharge between 15 and 16 percent of fresh water into the world’s oceans, with the Amazon river being the most important. The Amazon’s journey begins in Peru where it is born and ends up flowing into Brazil where its waters mix with those of the Atlantic Ocean for more than 100 km. It flows over more than 6,400 km with an average water flow rate of 225,000 m3 per second. In terms of territory, it covers 7 million km2, including nine countries (Brazil, Peru, Bolivia, Colombia, French Guiana, Venezuela, Ecuador, and Suriname).
The biodiversity of the Amazon is incomparable. This jungle is home to an impressive array of wildlife, including 427 species of mammals, 1,300 species of birds, 378 species of reptiles, and more than 400 species of amphibians. It stands out as the largest bird reserve in the world, with a fifth of all known poultry species globally. In addition, its richness extends to the freshwater fish that find their home in this ecosystem. In terms of flora, this nature reserve is home to approximately 20% of all known plant species in the world, totaling up to 80,000 varieties. More than 40,000 of these species are key to global climate regulation and the water cycle at the local level.
The Amazon Water Cycle
It is crucial to highlight the importance of the Amazon’s water cycle, characterized by its high rates of precipitation, evaporation, and river discharge. Its hydrology has an impact not only locally but also on a global scale. In short, much of the flow of the Amazon River comes from the melting of Peruvian glaciers. The humidity generated in the Amazon rainforest is due to the phenomenon of transpiration, whereby leaves release water vapor during photosynthesis through small pores that are located at the bottom of their leaves. This ability of plants to extract water and produce steam contributes to the formation of low clouds which, in turn, generate rainfall. The accumulation of these clouds gives rise to the well-known “flying rivers of the Amazon”, which transport water to the interior of the continent and have given rise to the Amazon being considered the “heart of mother earth”.
Flying Rivers
The first scientist to quantify the recycling of rainfall was Enéas Salati in the 1970s. Subsequently, other researchers and disciples of Salati, such as José Marengo, described the air flows of South America as “low-level jets”. It was the scientist Antonio D. Nobre who popularized the term “flying rivers” to describe the huge streams of water vapor that rise from the lush Amazonian vegetation and travel thousands of kilometres like rivers in the sky. Their work was instrumental in understanding and highlighting the importance of these unique atmospheric phenomena.
If we consider that each tree functions as a solar-powered evaporation machine, capable of transpiring up to a ton of water vapor, and we consider that the Amazon is home to around 600 billion trees, we can understand the magnitude of the phenomenon. In total, the trees of the Amazon rainforest pump a staggering 20 billion tons of water from the ground into the atmosphere. This process keeps the water in the air, where it is transported by the prevailing winds over thousands of kilometres, giving rise to “flying rivers” of invisible water vapor that reach a higher flow rate than the Amazon River itself.
However, the role of the “heart of mother earth” goes beyond nourishing the Amazon, as it also influences rainfall far beyond the rainforest. When these flying rivers reach the Andes mountains they unleash heavy rainfall and trees intercept these waters and return them to the atmosphere, thus feeding glaciers and lakes at high altitude. This water subsequently returns to the Amazon through the process of melting, completing the cycle.
In addition, flying rivers also move southward, carrying moisture as far as Paraguay, Argentina, central and southern Brazil, and other regions of South America. This distribution of moisture is vital to sustaining much of agriculture in South America and ensures the supply of drinking water, thus highlighting the critical role of the “heart of mother earth” in sustaining human activity.
How Does Climate Change Affect Flying Rivers?
It is widely recognized that the increase in greenhouse gas emissions and continued deforestation in recent decades have generated both an energy and water imbalance in the atmosphere. Not only does this phenomenon disrupt global weather patterns, but it could also have direct repercussions on Amazonian moisture transport in South America, a vital process for regional climate balance and associated biodiversity.
To test this, RUV LEMES et al.1 conducted research analyzing how local deforestation in the Amazon, and the increase in the atmospheric concentration of greenhouse gases, could be affecting the transport of moisture from flying rivers. The results were not positive and it was observed that the increase in the concentration of carbon dioxide, one of the main greenhouse gases of anthropogenic origin, induced a decrease in stomatal conductance (i.e. an evapotranspiration decrease). Therefore, less moisture was released into the atmosphere and this translated into a decrease in the transport of water by flying rivers. For example, it was observed that the transport of water from the Amazon basin to La Plata by these aerial rivers was reduced by 10 percent.
Deforestation of the tropical forest has led to a decrease of approximately 20 percent in vegetation cover, which has been replaced by approximately 5 percent savanna and desert. This reduction in the tropical forest, together with a temperature increase of 2°C, has resulted in a weaker water cycle and therefore less rainfall. In this way, it has been demonstrated that the transport of moisture from the Amazon rainforest to South America through flying rivers has being affected by the increase in temperature, together with the deforestation of the Amazon and the increase in greenhouse gases.
According to other recent research by FLORES et al.2, cumulative deforestation of 20 percent marks a tipping point, meaning that levels of deforestation and degradation of the Amazon have already passed a significant threshold. This raises an important question: How close are we to reaching the safe limits for the conservation of the largest continuous tropical forest on the planet? Estimates suggest that between 10 and 47 percent of the Amazon rainforest could disappear by 2050, underscoring the urgent need for effective conservation and protection measures.
Conclusions
Deforestation, the increase in global temperature, and the increase in greenhouse gases put us in a critical situation for the conservation of the Amazon, the largest tropical forest on the planet. We need to try to prevent large-scale deforestation of the Amazon, as it will not only have consequences for climate regulation at the global level but will also have a specific impact on economic and social conditions in South America. The massive loss of trees and the increase in atmospheric carbon dioxide translates into a decrease in humidity and the flow of flying rivers. The absence of these incredible systems would not only affect the global climate, but would also affect South America’s water cycle and its agriculture in a very particular way. It is essential to consider that the disappearance of the Amazonian forest entails not only the loss of invaluable biological diversity, but also the erosion of the region's cultural wealth. The Amazon is home to approximately 47 million people, including 2.2 million indigenous people and members of local communities, representing some 400 distinct ethnicities and cultures. Their disappearance would therefore have a serious impact on both ecological balance and the preservation of unique cultural heritage. If we cause irreversible damage to the Amazon rainforest, the “flying rivers” will cease their flow and “the heart of mother earth” will stop pumping water, resulting in a serious climate imbalance on a global scale. The preservation of this ecosystem is essential to maintaining the environmental and climatic stability of our planet.
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References
1. Ruv Lemes M, Sampaio G, Garcia-Carreras L, et al. Impacts on South America moisture transport under Amazon deforestation and 2 °C global warming. Science of The Total Environment 2023; 905: 167407. https://doi.org/10.1016/j.scitotenv.2023.167407.
2. Flores BM, Montoya E, Sakschewski B, et al. Critical transitions in the Amazon forest system. Nature 2024; 626: 555–564. https://doi.org/10.1038/s41586-023-06970-0.
