The Amazon is near "an irreversible tipping point", scientists say.

Two studies published in the journal Science on Thursday January 26 have for the first time estimated the effects of "degradation" in the South American biome.

The damage inflicted by human activity and drought are significantly greater than those previously observed, said the researchers, including from the Brazilian university Universidade Estadual de Campinas (Unicamp).

Public opinion has mainly focused on deforestation, which now reaches 17% of the original Amazonian area.

But the impacts of these "degradations" concern about 2.5 million km², or at least 38% of the Amazon still preserved.

According to studies, the forest – which covers nine countries – faces, in a few decades, changes that would normally have taken millions of years.

"As we approach an irreversible tipping point for the Amazon, the global community must act now," the authors of one of the papers write, adopting cautionary rhetoric rare in scientific reporting.

"After this point, in 30 to 50 years, we will lose between 50 and 70% of the forest, which will become an open ecosystem, very degraded with an immense loss of biodiversity", explains to the daily O Globo the Brazilian researcher and l one of the authors, Carlos Nobre.

These "degradations" resulting from human activity could become by 2050 one of the main sources of carbon emissions.

And this regardless of the increase or decrease in deforestation, the study continues.

"The degraded area in the Amazon and the carbon emissions due to degradation are equal to, if not greater than, those due to deforestation," study leader David Lapola, a researcher at the Center for meteorological and climatic research applied to agriculture from Unicamp and doctor from the German University of Kassel.

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Drought as the main "degradation"

During their study, the researchers focused on the consequences of phenomena other than direct deforestation: drought, fires, selective logging – when specific elements of the forest are exploited, leaving others around unaffected – or edge effects – when changes due to deforestation affect habitats at the edge of remaining forest.

The main phenomenon among these degradations is drought.

The other phenomena have degraded at least 5.5% of Amazonian forests between 2001 and 2018. However, once the effects of drought are included, the deteriorated area represents at least 38% of the Amazon still preserved today, reveal the scientists .

They analyzed data from Brazil and other neighboring countries, based on previous studies and satellite images from 2001 to 2018.

“Extreme drought has become increasingly common in the Amazon due to changing land use patterns and human-induced climate change affecting tree mortality, the number of fires and emissions. of carbon in the atmosphere," the scientists said.

“Forest fires have intensified during the drought years,” they added, warning of the dangers of “large fires” in the future.

The edges of preserved areas increasingly weakened

As with deforestation, fires – even over – can continue to compromise preserved areas, triggering edge effects.

Reduced to isolated sections, sometimes surrounded by agricultural or urban areas, these outermost fragments become increasingly hot, drier, more exposed to new fires and inhabited by different species.

The original characteristics of the area then gradually disappear.

A vicious circle of extreme natural disasters then sets in.

The team led by David Lapola estimates, for example, that the two most intense episodes of drought in the region, in 2005 and 2010, led to giant fires: they respectively reached sizes two and four times greater than the average forest fires in the area, reports the Brazilian daily Folha de São Paulo.

According to a second study also published in the journal Science, conducted by James Albert, of Lafayette University in the US state of Louisiana, the effects go beyond droughts: extreme floods also hit the region in nine of the 15 last years.

However, the last century has known only seven events of this intensity.

Parts of the 'planet's lung' emit more CO2 than they absorb

These phenomena are not only becoming more serious, but are also accelerating and becoming the norm, is alarmed by this second study, focused on the consequences of human activity on the Amazonian ecosystem.

It takes stock of conditions that the Amazon has never seen in tens of millions of years of existence.

The effects are already visible in the short term.

In addition to the loss of biodiversity and the silting up of rivers, the researchers warn that, in large areas, the "lung of the planet" no longer absorbs CO2 but, on the contrary, it emits it. .

While forests absorb carbon under natural conditions, especially during the growth of young plants, wooded areas end up emitting CO2 when exposed to extreme conditions… A mechanism that further worsens the effects of global warming.

According to Brazilian geologist Pedro Val, a professor at New York University and also a signatory to one of the articles, the answer must be an end to deforestation: "If you cut down forests, you start to have an impact on the amount of water you have in this system, on energy exchange, on heat, it increases the amount of precipitation and storms that affect the soil, this causes erosion and loss of nutrients, and the forest loses some of its ability to use these nutrients to self-regenerate."

“Forests store more than 150 billion tons of carbon, and these tons will become more than 200 billion tons of carbon dioxide emitted into the atmosphere, making it impossible to meet the Paris Agreement targets to maintain the temperature below 1.5°C", he adds, questioned by O Globo.

"To abandon the Amazon is to abandon the biosphere"

Luiz Inacio Lula da Silva has pledged to end deforestation in the Amazon, after four years of Jair Bolsonaro's far-right presidency under which environmental protection legislation was ignored or weakened.

The Brazilian president wants to organize in the coming months a summit of the countries of Amazonia, to which he has invited his French counterpart Emmanuel Macron.

Lula underlined how important it was for France to attend this summit, the Amazon rainforest extending in particular to Guyana.

Because the picture could become darker without control of deforestation.

According to the researchers of the studies, the consequences go far beyond the environment: humanitarian issues also arise, such as food insecurity and mass migration.

Part of these problems can be solved by applying the planned legislation, especially with regard to Brazil, explain the experts.

But new "laws to avoid the worst consequences" must "be immediately enacted", write the authors of the article.

“Approaches capable of preventing the most negative outcomes have already been successfully identified, but their implementation is a matter of leadership and political will. To abandon the Amazon is to abandon the biosphere,” they insist. rare way in scientific reports.

(With AFP and Reuters)

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