Scientists warn that 10% of the Amazon has a high risk of being converted into a drier and degraded ecosystem by 2050, while 47% has a moderate transitional risk.
The article, published in Nature, used evidence collected by field researchers who are already witnessing changes in the rainforest as a response to increasing temperatures, extreme droughts, fires and deforestation.
These regional tipping points may lead to a systemic breakdown of the biome unless humanity controls global warming, stops deforestation and starts to recover degraded parts of the rainforest, the authors say.
The possibility of the Amazon reaching a tipping point, after which it would no longer sustain itself as a rainforest, has been discussed since the 1990s when the first articles addressing the issue were published by the scientists Carlos Nobre and Thomas Lovejoy. Since then, other researchers have analyzed the topic with important progress, including the 2018 emblematic study that delimited a 20-25% deforestation threshold after which the tipping point would be inevitable. As of now, 13% of the biome has already been lost , according to the Monitoring of the Andean Amazon Project (MAAP), a U.S.-based nonprofit.
Now, a group of 24 scientists has taken an important step in trying to predict not only when, but also how these major changes would happen in such a complex landscape. “The first tipping point papers used relatively simple transition models that related temperature, rainfall, climate and forest,” Gilberto Câmara, former Director of INPE, Brazil's space research agency, told Mongabay in a video call. “It is like if I tell you, ‘I'm in New York and I can go to Washington,' without telling me how you're going to get there. The original articles were like teleportation. This article is already an attempt to tell you what routes there are,” he said.
The research , published by Nature magazine on Feb. 14, used field evidence and disturbance factors such as roads, temperature and extreme drought events to point to the stretches of the rainforest more susceptible to converting into another landscape. To evaluate how climate change could affect the course of events, the authors used prediction models from the United Nations Intergovernmental Panel on Climate Change (IPCC).
They concluded that 10% of the biome has a relatively high potential to transition to a drier, degraded and less biodiverse ecosystem, which no longer could be considered a tropical forest. These areas are mainly in Guyana, Venezuela, Colombia and Peru. Moreover, 47% of the biome has a moderate transition potential, including relatively remote parts of the central Amazon.
To predict the future, the researchers turned to the vast body of literature from field researchers who have been observing how different parts of the Amazon are reacting to stress factors such as warming temperatures, fires and deforestation. “You already have changes pointing to regional tipping points,” Marina Hirota, a Santa Catarina Federal University professor and one of the study's lead authors, told Mongabay. Heading the research is also Bernando Flores, from the same university.
The Nature paper listed three possible post-tipping point ecosystems that are already a reality in some parts of the Amazon and which may spread to other areas if nothing is done to stop deforestation and control global warming: the degraded forest, which is a poor forest dominated by native opportunistic species; the degraded open canopy ecosystem, home to palm and fire-tolerant species; and the white sand savanna, where savanna trees and native herbaceous plants predominate.
The term “savannization,” used in the first tipping point articles, is gradually being abandoned. “The Cerrado [the Brazilian savanna] has the highest rate of biodiversity of any tropical savanna in the world, as well as an enormous amount of carbon stored in the soil,” Nobre, who co-authored the Nature article, told Mongabay. “This ecosystem that the Amazon would become looks like the Cerrado, but it doesn't have the same biodiversity and stores very little carbon.”
These changes in the Amazon landscape result from plant adaptation to drier ecosystems. “The forest's ability to adapt is to have fewer trees and reduce its floristic composition,” Marlena Quintanilla, director of research and knowledge at the Bolivian-based NGO Friends of Nature Foundation , told Mongabay. “As a result, there is less food and wild fruit. We still don't have precise answers about how biodiversity is changing as a result of this change in the forest.”
Amazon people already feel climate change and the advance of deforestation. In 2023, a historic drought associated with intense forest fires left entire cities shrouded in dense clouds of smoke. “It has been 3 weeks of a struggle to breathe. The smoke is everywhere, making even the simpler of all tasks, e.g. to sleep, a battle for air,” the scientist Érika Berenguer, who researches the impact of fires in the Amazon , tweeted in October.
“Ecosystems will adapt to the new conditions, but the greatest impact will be on local producers and local communities,” said Quintanilla, who also stressed the effects of an Amazon collapse on the countries' economies and food production.
Besides holding more than 10% of the planet's terrestrial biodiversity, the rainforest stores an amount of carbon equivalent to 15–20 years of global CO2 emissions. A 2021 study, however, showed that southeastern Amazonia had already become a carbon source due to fires and deforestation.
“You lose biodiversity, you change the way the forest functions in terms of how much water it releases and how much carbon it stores. There's a whole feedback mechanism that keeps these ecosystems trapped in another state. This is already happening,” Hirota said.
A systemic breakdown
Even undamaged areas of the forest, far away from the deforestation hotspots, are already reacting to what the scientists call regional tipping points. “The Amazon processes are connected,” Quintanilla said, referring to the moisture generated by trees' evapotranspiration and carried to other parts of the forest by the wind. If there is intense tree mortality in one place, it means less water for the rest of the biome.
“In the Bolivian Amazon, we have seen a greater die-off of adult trees and a drop in nut production. These intact areas, where deforestation is not taking place, are being impacted by what is happening in other parts of the Amazon,” said Quintanilla, who lives in the Bolivian city of Santa Cruz de La Sierra.
The authors highlighted that Brazil holds 60% of the biome area and is the largest supplier of rainfall to western Amazonian countries. Up to one-third of the total annual rainfall in the Amazonian territories of Bolivia, Peru, Colombia and Ecuador depends on water from Brazil's portion of the Amazon forest. “There is international connectivity and there must be greater discussion about how policies related to deforestation in Brazil will affect the climate in other countries to the west,” Matt Finer, senior research specialist and director of MAAP, told Mongabay in an email.
Thanks to this connectivity, the advance of regional tipping points could lead to the collapse of the whole biome, as the first studies on the topic predicted. “It is like the human body,” Hirota exemplified. “If one organ starts to collapse at one point, then another starts to collapse at another point, there comes a time when you have multiple failures and there's no way of sustaining the system.”
To avoid this scenario, the study pointed to certain thresholds that can't be crossed. Temperature, for instance, cannot increase more than 1.5 °C (2.7 °F) above pre-industrial levels, as established by the Paris Agreement. “Keeping the Amazon forest resilient depends firstly on humanity's ability to stop greenhouse gas emissions, mitigating the impacts of global warming on regional climatic conditions,” the researchers wrote.
Deforestation should not only stop immediately, but the Amazonian countries must restore at least 5% of the destroyed forest. “We have to take a large part of these almost 2 million square kilometers [772,000 square miles] that have been deforested and degraded and create huge forest restoration projects,” Nobre said.
Creating new protected areas and Indigenous territories is also crucial to avoid the collapse of the world's largest rainforest. “Almost half of the Amazon has been maintained thanks to Indigenous and protected areas. It is important Indigenous territories do not become islands, as it is happening,” said Quintanilla. “We can't propose solutions without the local players,” added Hirota.
Banner image: An IBAMA agent views illegally felled trees inside Jamanxim National Forest in 2014. Photo courtesy of IBAMA.
Citations:
Lovejoy, T. E., & Nobre, C. (2018). Amazon tipping point. Science Advances doi:10.1126/sciadv.aat2340
Flores, B. M., Montoya, E., Sakschewski, B., Nascimento, N., Staal, A., Betts, R. A., … Hirota, M. (2024). Critical transitions in the Amazon forest system. Nature doi:10.1038/s41586-023-06970-0
FEEDBACK: Use this form to send a message to the author of this post. If you want to post a public comment, you can do that at the bottom of the page.