The Amazon "lung of the Earth", really?


The lungs of the Earth are burning. The lungs of the Earth are sick. In recent weeks, the term is used on all forums by politicians, journalists and some celebrities as tens of thousands of fires burn the Amazon basin.

President Macron's tweets about forest fires in the Amazon.

On August 22, French President Emmanuel Macron tweeted "The Amazon, the lung of our planet that produces 20% of our oxygen, is on fire."

Photo: Twitter

For example, on August 22, on the eve of the G7 Summit, French President Emmanuel Macron tweeted: The Amazon, the lung of our planet that produces 20% of our oxygen, is on fire.

Gazoullis of the actor Leonardo Dicaprio.

The actor Leonardo DiCaprio's gasoullis on the situation in the Amazon.

Photo: Twitter

Transplantation impossible

If the image magnificently illustrates an idea, it can become a source of eco-anxiety, this new phenomenon appeared for some years which causes some people a pain of living, a sadness or an anger at their own helplessness and in front of the inaction of others in the face of climate change.

And if, like the human, the planet can not live without its lungs? A transplant is at least difficult to envisage.

Now, the comparison, however effective on the mind, remains a beautiful metaphor and does not survive the test of the second degree.

In humans, the lungs have two main functions. That of transferring into the blood the oxygen present in the air and that of evacuating in the air the carbon dioxide present in the blood.

Illustration of the human respiratory system.

The human respiratory system.

Photo: iStock

For the exercise, combine the first function with the photosynthesis of the Amazonian forests that produces oxygen, and the second with carbon sinks that capture and store carbon in the atmosphere.


  • The Amazon basin occupies nearly 40% of the area of ​​South America and is spread over nine countries: Brazil, Bolivia, Peru, Ecuador, Colombia, Venezuela, Guyana, Surinam, and Guyana (France);
  • No less than 60% of its surface is in Brazil;
  • The Amazon is the largest tropical forest on the planet.


Most of the oxygen in the air we breathe is produced by plants through the process of photosynthesis, by which they synthesize organic matter using light as a source of energy.

<q data-attributes = "{" lang ": {" value ":" fr "," label ":" French "}," value ": {" html ":" As a whole, tropical forests are responsible for more or less 34% of the photosynthesis carried out on the mainland "," text ":" As a whole, the tropical forests are responsible for more or less 34% of the photosynthesis carried out on the mainland "}}" lang = "fr">Tropical forests as a whole are responsible for more or less 34% of photosynthesis on the mainland, said Professor of Ecosystems Science Yadvinder Malhi, Oxford University, in work published in 2010.

According to these calculations, the Amazonian forests are responsible for more or less 16% of the oxygen produced from the mainland.

Aerial view of the Brazilian Amazon rainforest.

The Amazon forest

Photo: AFP / Getty Images / AFP

But we must also consider the contribution of the oceans who participate even more in the process, up to about 50%, thanks to the phytoplankton they contain.

Taking the oceans into account, the scientist estimates the oxygen supply of the Amazon to less than 10%, probably around 5%.

A very high percentage on a planetary scale, but which can not be compared to the vital role of the lungs in humans.

In addition, Professor Scott Denning, Atmospheric Specialist at Colorado State University, says that fires in the Amazon do not threaten atmospheric oxygen. The scientist explains that almost all the oxygen we breathe comes from the oceans and there is enough for millions more years.

Even if all the organic matter on Earth were burning at the same time, less than 1% of the planet's oxygen would be consumed.

Scott Denning

So, do not worry about the air we breathe, even if the Amazon rainforest disappeared overnight.

Carbon absorption

A carbon sink is a reservoir that captures and stores carbon in the atmosphere.

The largest natural reservoir is the ocean sink, which uses coral and plankton to absorb between two and three billion tonnes of carbon a year.

The other big wells are forests and peat bogs. Wood and tree foliage capture large amounts of CO2.

The French scientist Philippe Ciais, forest specialist at the Laboratory of Climate and Environmental Sciences (LSCE), believes that <q data-attributes = "{" lang ": {" value ":" fr "," label " : "French"}, "value": {"html": "the Amazonian forest represents 10% to 20% of global CO2 removals by vegetation and subsoils "," text ":" the Amazonian forest accounts for 10% to 20% of global CO2 removals by vegetation and subsoils "}}" lang = " en ">the Amazon rainforest accounts for 10% to 20% of global CO2 removals by vegetation and subsoils.

The Amazon is therefore one of the planet's largest sources of carbon sequestration on the Earth's surface, but not the largest.

If the Amazon were deforested, not only would this carbon sink be lost, but it would be transformed into a source of CO2 for the atmosphere.

Philippe Ciais

Another researcher, Jean-Pierre Wigneron of France, from the National Institute for Agricultural Research, recalls that Amazonian ecosystems actually capture a huge amount of CO2, they also emit a huge amount.

According to him, the data concerning only the Amazonian forests do not exist, but those of the tropical forests of South America as a whole, knowing that the Amazon represents 70% to 80%, show thatthey emit as much carbon as they sequester.

A large portion of South America, partially covered with clouds and smoke.

The smoke produced by forest fires raging across Brazil is visible from space.

Photo: NASA / NOAA

These emissions, even if they are largely linked here to deforestation and mortality, often as a result of droughts, make the net carbon balance of the tropical forests of South America overall neutral over the last ten years.

The carbon sink of the land surface currently would be in boreal and temperate forests. They are the ones who clean the atmosphere. These forests (boreal and temperate) absorb more carbon than they release.

Jean-Pierre Wigneron

It is thought that the carbon stock (biomass) of boreal forests is increasing and it is cleaning up the atmosphere. In this sense, the Amazon would not be the first lung of the planetadds Mr. Wigneron.

However, this carbon storage capacity makes Amazonia one of the most important climate stabilizers of the earth. Without this ability, temperatures may increase, and the warming cycle may increase.

Satellite image showing phytoplankton off the coast of New Zealand.

Phytoplankton off the coast of New Zealand.

Photo: NASA / Robert Simmon and Jesse Allen

In conclusion, if the title of lung of the Earth had to be awarded to a particular geographical entity, the oceans would deserve a lot more than the Amazon.

Unique biodiversity threatened

A member of the Dessana tribe.

A member of the tribe Dessana who people the Amazon.

Photo: iStock / Rodolpho Reis

The consequences of these forest fires in the Amazon on diversity are no less disastrous, both ecologically and environmentally as well as socially and culturally.

Nearly 3 million Indians populate the Amazon in 420 tribes, of which about sixty live in total isolation, show the figures of the Organization of the Amazon Cooperation Treaty, a group of eight countries sharing the Amazon rainforest .

No less than 86 languages ​​and 650 dialects are spoken.

Close up on the head of a jaguar.

The forests of the Amazon are one of the last refuges of the jaguar (Panthera onca).

Photo: iStock / tane-mahuta

The region, whose biodiversity is unique in the world, has some 30,000 species of plants, 2,500 species of fish, 1,500 birds, 500 mammals, 550 reptiles and 2.5 million insects.

Since 1999, no less than 2,200 species of plants or animals have been discovered there.

By comparison, the boreal forest is home to about 20,000 plant and animal species.

Source link


Please enter your comment!
Please enter your name here

one + 11 =