Up to 40% of what remains of the Amazon has already suffered degradation – 01/26/2023 – Environment

Two studies that have just been published present a worrying diagnosis of human impacts on the Amazon. The works, co-authored by Brazilian scientists, show that up to 40% of the remaining areas of forests in the region have already suffered some type of degradation, and that the speed of environmental changes taking place now can be thousands of times greater than at any time in the past. .

The surveys, which seek to synthesize the main data obtained to date on the health of the Amazonian ecosystems, are in the most recent edition of the specialized American journal Science, one of the most influential in the world.

“As we approach an irreversible tipping point for the Amazon, the global community needs to act now. Approaches capable of preventing the most negative outcomes have already been successfully identified, but implementing them is a matter of leadership and political will. Amazonia is abandoning the biosphere”, write the authors of one of the articles, adopting a stern warning rhetoric that rarely appears in scientific reports.

The study whose conclusion brings the sentences above seeks to estimate the current rates of change in dozens of aspects of the Amazonian environment. The work was coordinated by James Albert, from the University of Louisiana at Lafayette (USA), and has the participation of researchers from several Brazilian institutions, including climatologist Carlos Nobre, from the Institute of Advanced Studies at USP (University of São Paulo). .

In the second survey, a team coordinated by David Lapola, from Unicamp (State University of Campinas), takes an X-ray of the main processes of forest degradation in the Amazon. Degraded forests, although they have not suffered “clear cutting” –deforestation itself– face serious problems, such as damage caused by fire, intense droughts and logging.

Furthermore, the deforestation process is capable of degrading forest areas that remain standing, because the tendency is for them to be reduced to forest fragments – islands surrounded by agricultural activities, roads or even urban areas. In these fragments, the so-called edge effect begins to act. In these cases, forest areas adjacent to non-forested patches tend to be warmer, drier, with different species composition and more subject to fire. All this causes the original characteristics of the forest to begin to be lost in that fragment.

According to surveys, while clear-cutting has already reached around 17% of the area normally covered by the Amazon biome, the impacts of forest degradation can be much broader. The total degraded area, in this case, would reach around 2.5 million square kilometers, or 38% of the remaining forests.

Several processes enhanced by human action are relevant to the problems detected in both studies. One of the things that have scared researchers the most is the increase in extreme weather events in the region, which is directly related to the unbridled emission of gases that cause the greenhouse effect.

The team coordinated by David Lapola calculates, for example, that the two great droughts of 2005 and 2010 led to the burning of an area of ​​forest with double and quadruple the average annual size of forest fires since the beginning of this century. According to the team led by Albert, both extreme droughts and floods have hit the region in nine of the last 15 years. In the entire past century, on the other hand, there have been only seven such events.

The big problem, therefore, is that these impacts are not only getting more severe, but are also accelerating and becoming more common, at levels that are incomparable to anything that the Amazon has faced over tens of millions of years of evolutionary history.

This has already visible consequences in the short term. In addition to the loss of biodiversity and the silting up of rivers, in many degraded places the forest is ceasing to be what researchers call a carbon sink and becoming a source of carbon. Simply put: while it is normal for the forest to remove carbon dioxide from the atmosphere through plant growth, thus mitigating the warming caused by this greenhouse gas, the forest under stress can end up releasing more carbon dioxide into the atmosphere, helping to make their own problems worse.

Furthermore, it has already been shown that rain in the Amazon depends, to a large extent, on the ability of the forest to recycle the very water it “transpires” – to be more exact, about half of the 14.1 trillion cubic meters of water that fall in the region every year come from the forest itself. Extreme droughts, fires and deforestation increasingly increase the risk that this faucet will turn off, which could have dire consequences for the climate of all of South America. Ultimately, forest degradation could end the typical characteristics of the Amazon, transforming it into a kind of impoverished savannah.

Most of these problems can be solved simply by complying with the law, at least in the case of Brazil, but more ambitious approaches will be needed to significantly minimize the risk of an ecosystem collapse, say the researchers.

Investment in clean energy in Brazil and in the world is essential to curb climate change at a global level. In addition, in regional terms, the Amazon needs to start its transition to the bioeconomy, with high added value products based on the region’s biodiversity and a brake on the expansion of export agriculture.