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More than a third of the undeforested Amazon rainforest is degraded by fires, droughts and human action

2023-01-26T19:27:34.952Z


Two scientific reviews published in 'Science' warn of the accelerated deterioration of this tropical forest that is key to biodiversity and the planet's climate


The situation of the Amazon jungle is critical.

Although the alarm around this key tropical forest for biodiversity and the planet's climate is generally graduated based on deforestation figures, an international team of researchers has now calculated that more than a third of the remaining Amazon without deforestation is degraded by droughts, fires or other effects related to human activities.

This is one of two studies published this week in the journal

Science

that update scientific knowledge about the current state of the Amazon rainforest, both with worrying conclusions.

This first work, carried out by some thirty scientists from the University of Lancaster, in the United Kingdom, and from different Brazilian institutions, such as the State University of Campinas, the Institute for Environmental Research of the Amazon (IPAM) or the National Institute of Space Research (INPE), does not pay attention to the part of the Amazon that has been left without trees, but to the one that continues to be maintained as a jungle.

"Deforestation implies a loss of the forest canopy and a change in land use [for example, to agricultural cultivation], but degradation is a process that affects the remaining forests," says Jos Barlow, a researcher at the University of de Lancaster and one of the authors of this scientific review, which gives concrete data: "While around 17% of the Amazon has already been deforested, 38% of the remaining forest may be degraded in some way."

This degradation occurs due to the border effect with already deforested areas, selective logging, fires or extreme droughts, which researchers say are intensifying due to climate change caused by the human species.

Although in this case the forest does not disappear, its deterioration has effects on the carbon cycle, the functioning of ecosystems and the livelihoods of local populations whose special relevance is now beginning to be understood.

Thus, for example, according to scientists' estimates, these disturbances in the Amazon without deforestation generate carbon emissions of between 0.05 and 0.20 Pg (petagrams) of carbon per year (one petagram equals one gigaton, that is, say, to a billion tons),

As David M. Lapola, a researcher at the Earth System Sciences Laboratory of the State University of Campinas and lead author of the paper, points out, “this does not mean that deforestation should not be focused on, especially after it has increased again in the past year, but our review shows that there are other important processes underway that have been mostly overlooked until now."

Although the work shows the magnitude of the current degradation of the non-deforested tropical forest, the researchers emphasize that deforestation also contributes to aggravating this phenomenon, either directly, by exposing the edges of the forest to the warmer microclimate of open fields, or, indirectly, making fires more likely or making it easier to penetrate the forest to carry out felling.

As Barlow points out, “our study considers preventing deforestation critical, but it also shows that this alone will not be enough: we need new interventions that address illegal logging and reduce the risk of forest fires, which are increasingly likely due to change climate".

The breakneck pace of change

The second study published in

Science

is no less alarming for the Amazon rainforest, considered by scientists to be a key component of Earth's biodiversity and climate.

Not surprisingly, this tropical forest that occupies 0.5% of the Earth provides shelter for 10% of all known plants and vertebrates, as well as playing a significant role in global water or carbon cycles.

In this case, researchers from another large international team in which the University of Louisiana at Lafayette (USA), the University of Bergen (Norway) or the University of São Paulo (Brazil) have participated in other institutions have compared the rhythm of changes due to human action in the Amazon and other large areas of South America and the world.

Their conclusion is that the processes that alter the ecosystems of the Amazon are hundreds or thousands of times faster than other natural climatic and geological phenomena.

The main causes are changes in land use (due to clearing, forest fires, and soil erosion), changes in water use (due to the construction of dams, the fragmentation of rivers, and increased sedimentation by deforestation),

According to the authors of this second work, the key message is that the Amazon rainforest is being degraded by human industrial activities at a rate well above anything previously known, endangering its vast reserves of biodiversity and ecosystem services of planetary importance. .

Furthermore, scientists predict that, given the enormous role of the Amazon in the planetary hydrological cycle, large-scale deforestation of this region is expected to push the entire Earth system into a qualitatively different global climate.

Researcher Barlow, from Lancaster University, believes that "the two studies show that the situation is incredibly urgent and highlight the importance of halting further deforestation and addressing degradation to make the Amazon as resilient as possible to climate change." .

For Lapola, from the Brazilian University of Campinas, "shamefully, we did not find successful and widespread ways of living and using the largest tropical forest in the world."

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Source: elparis

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