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Climate: why the Amazon rainforest now emits more carbon than oxygen

2021-05-07T05:52:04.564Z


A Franco-American study reveals for the first time that the “green lung” of the planet rejects more C02 than it absorbs. In question


Lungs: organs of respiration allowing the exchange of vital gases.

If lovers of the Amazon rainforest readily compare this South American gem to the planet's green lung, it is less for its ability to oxygenate the Earth than for its ability to absorb, and therefore, eliminate carbon dioxide in it. atmosphere.

Except that this natural function, vital for the survival of the globe, is in the process of collapsing.

A Franco-American team of researchers from the National Research Institute for Agriculture, Food and the Environment (INRAE), CEA and the University of Oklahoma, has just demonstrated for the first time that the Brazilian rainforest has released over the past ten years more carbon than it has captured.

According to scientists, whose results were published in the journal Nature Climate Change, degradation of the jungle, caused by both human activities and climate change, is the main cause of this disruption.

Deforestation multiplied

"The Amazon is no longer a carbon sink", sums up researcher Jean-Pierre Wigneron, co-author of the study and research director at INRAE ​​in Bordeaux, with a sigh. This specialist in remote sensing of forests has been studying for years the images and data of humidity and biomass provided by the satellites of the European Space Agency.

And the results of these observations are clear: "Over the past ten years, the biomass, that is to say the weight of the vegetation of the Amazon per hectare, has fallen by 700 million tonnes", explains the French researcher.

Climate change and human activities are weakening the Amazon rainforest and its essential carbon storage function.

And despite the recurring alarm signals issued by scientists, the pace of chainsaws has accelerated further in recent years: deforestation has increased sharply after the change of Brazilian government in 2019, from one million hectares in 2017. and 2018 to 3.9 million hectares!

Read also Deforestation: according to a WWF report, the massacre continues

When logging companies do not raze entire swathes of the jungle, fires and drought take care of it.

“There have been a lot of fires that released carbon into the atmosphere, but also a great many tree deaths following the 2015 drought,” recalls Jean-Pierre Wigneron.

By analyzing the evolution of carbon stocks, it turns out that it is precisely in 2015 that the carbon losses of the forest were the most important: three times more than in 2019. According to scientists, the degradations of forests have an impact three times greater than deforestation.

VIDEO.

Amazon fires: the planet's green lungs go up in smoke

"In certain areas of the forest, as is also the case in Madagascar, the soils are so eroded that they are irreversibly lost," laments the scientist.

It is a vicious circle because the Amazon rainforest, by sweating a lot, maintains the cycle of rains in the region.

But global warming accentuates episodes of extreme drought and contributes to the mortality of part of the vegetation.

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"A historical reversal"

The result: "a historic trend reversal" in the carbon footprint of the tropical forest. "During the period 2010-2019, the carbon losses in the heart of the Brazilian massif are greater than the carbon gains by around 18%", underlines the study. "While we were counting on the Amazon rainforest to offset our CO2 emissions, it symbolically shifted to the side of emitters", laments the expert.

The scientist is all the more worried that other forests around the world are similarly suffering, especially in Canada and Siberia. If we prefer to see the "green" half full, we can take comfort in telling ourselves that the western part of Russia is doing quite well. "There are huge areas where the forest grows back," decrypts the French scientist. Thanks to gigantic campaigns to reforest areas that can be the size of France, China is, for its part, becoming one of the most important carbon sinks in the world. "

Source: leparis

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