Slowly but surely, one of the “lungs of the earth” begins to work in reverse. Has humanity lost one of its greatest allies?
We often speak of the Amazon rainforest as the lung of the planet. In reality, this role falls rather to the ocean; but the expression clearly illustrates the importance of this area. This notion could change radically, however. That’s the conclusion of a massive study, which has seen a team of Brazilian researchers compile hundreds of air samples collected at high altitudes over the past ten years. According to them, this very important forest, particularly the South-East zone, would henceforth be net emitter of CO2.
Usually, this forest plays a crucial role in the carbon cycle. It is an extremely complex chemical, biological and geological cycle. Its dynamic is intimately linked to life on Earth on many levels. And in this cycle, forests are a carbon sink; this is what we call the reservoirs that will sequester atmospheric carbon. Thus, not only the wood, but also the soil and a part of the living beings which reside there, constitute carbon sinks among the most important for the emerged lands, much more effective than the other types of vegetation. The Amazon rainforest is therefore an essential component of biological dynamics as we know it.
Human activity, indisputable culprit
But today, this region now emits more atmospheric carbon than it captures. And when such an important player in this cycle begins to radically change their behavior, it can only be a bad omen. And for good reason: close to 450 billion tonnes of carbon are trapped in the Amazon.
This puzzling finding, the researchers attribute to the combined influence of two factors. The first is deforestation. Since 1970, the area of forests in the region has decreased by 17%. And quite often, according to the study’s authors, cleaning up areas for agriculture and animal husbandry is often carried out by fire, which further amplifies the problem. The other concern is global climate change. Temperatures in the area have risen by about three degrees from pre-industrial times; according to the researchers, this is three times more than the planetary average. However, we know that the more the temperature increases, the less suitable the plants to store CO2.
A tipping point with heavy consequences
This is worrying news, because the Amazon rainforest is one of the main climatic tipping points on our planet. Among them, we also find the Siberian permafrost, a veritable climate bomb loaded with greenhouse gases that are just waiting to escape. We can also cite the Greenland sea ice, the coral reefs… so many extremely vulnerable systems. If a point of no return is reached in just one of these systems, its action on the famous vicious climatic circles would be so strong that it could, in the long term, switch all the others.
Kind of like a domino file, whose fall would radically change the face of the world as we know it. If the Amazon were to become a long-term source of carbon, managing the current climate crisis would be even more difficult. Hopefully this dynamic is still reversible; but it is quite possible that we have already corrupted one of our most precious allies, who is now turning against us.
The text of the study is available here.