"Flying rivers" or "aerial rivers", a natural phenomenon bring moisture out of the forests to better irrigate them. These atmospheric waterways, which have been in existence for a long time, are vital for the Amazon forest basin.


Sometimes you may notice in photos taken in or near the world's largest forests like the Amazon thick clouds floating above the trees. But these vapor trails in the sky actually play an important role.

Commonly referred to as "floating rivers" or "aerial rivers," these atmospheric waterways play an essential role in the balance of ecosystems.

It's well known that the Amazon, the largest tropical forest in the world, is characterized by high humidity.

What is less well known is that flying rivers play a key role in ensuring the forest's thermoregulation.

This phenomenon is a direct result of evapotranspiration, a process during which moisture is evacuated from the trees in the form of vapor in astronomical quantities that can reach 20 billion tons each day!

These thick accumulations of water vapor are then transported by the winds towards the mountains, which causes a suction effect that will attract other humid currents, this time from the oceans.

This mechanism, dubbed the "biotic pump" by scientists, then causes heavy rainfall to irrigate the land, soil and forests of the Amazon.

The range of the flying rivers is so powerful that they pour out across thousands of kilometers, covering the entire forested areas of the Amazon, including Bolivia, Paraguay and northern Argentina, according to the experts who have studied them.

The Amazon saw a loss of 18 trees per second in 2021

Gerard Moss, a Swiss-Brazilian engineer and pilot who described this phenomenon in 2006 after flying over the Amazon, was one of the first to explore and document this phenomenon.

The specialist found that large accumulations of water were moving through the sky from the oceans to the forests. Gerard Moss shared his findings with Professor Antonio Nobre, a researcher at the Brazilian National Institute for Space Research (INPE).

Together, they launched the "Rios Voadores" research project to better understand this natural phenomenon. "The humidity carried by these “airborne rivers” is responsible for much of the rain that falls in the Centre-West, Southeast and South of Brazil," explains the website dedicated to their project.

However, just like the forest from which they emanate, flying rivers are threatened by climate change.

Their decline is directly linked to the mass deforestation of the Amazon. In 2021, this vast forest lost an average of 18 trees per second.

And according to official data from Brazil's National Institute of Space Research (INPE), the Brazilian part of the Amazon (60%) lost 3,988 sq km of forested area between January and June 2022.

"However, with global warming and climate change threatening to change rainfall patterns on a world-wide scale, it is time for us to take a better look at the environmental services provided by the rainforest before it is too late," the researchers outlined..

Less and less rain in the Amazon

In August 2022, research published in the journal PNAS also highlighted the consequences of the increasing scarcity of rainfall, which could deplete the Amazon basin's moisture reserves and reduce its forest cover. These effects are all the more worrying because they are not confined to a single region.

"As lack of rain strongly decreases the water recycling volume, there will also be less rainfall in neighboring regions, hence putting even more parts of the forest under significant stress," the study states.

Brazil, home to about one-third of the world's remaining primary rainforest, has seen the rate of destruction of its forests accelerate in recent years, according to data from Global Forest Watch (GFW), the World Resources institute (WRI) and the University of Maryland.

In 2021, destruction not caused by fire, often related to the creation of agricultural areas, was 9% greater compared to 2020. This percentage exceeds 25% in some states of the western Brazilian Amazon.