The Amazon Rainforest represents over half of the Earth’s remaining rainforests. It is the largest and most biodiverse tract of tropical rainforest in the world, with an estimated 390 billion individual trees in about 16,000 species. It is also home to 30 million people.
Today, the Amazon Rainforest is almost at the point of no return with rapid deforestation, and other forces like wildfires, interacting to limit its ability to self-repair.
A new study led by the Federal University of Santa Catarina in Brazil, and with international experts, has identified where their combined effects could produce a ‘tipping point’ – in which the forest is so fragile that just a small disturbance could cause an abrupt shift in the state of the ecosystem. The research revealed that up to 47% of the Amazonian forest is threatened and identifies climatic and land-use thresholds that should not be breached to keep the Amazon resilient.
Lead author Bernardo Flores, from the University of Santa Catarina, said:
“Compounding disturbances are increasingly common within the core of the Amazon. If these disturbances act in synergy, we may observe unexpected ecosystem transitions in areas previously considered as resilient, such as the moist forests of the western and central Amazon.”
These ecosystem transitions could include a forest that may be able to recover but is still trapped in a degraded state and dominated by opportunistic plants such as bamboos and vines, or a forest that is unable to recover and remains trapped in an open-canopy, flammable state.
The research findings are important because of the vital role the Amazon plays in the global climate system. For example, Amazonian trees store massive amounts of carbon which, if released, could accelerate global warming.
Co-author, Dr Adriane Esquivel-Muelbert from the Birmingham Institute of Forest Research, said:
“We have evidence showing that rising temperatures, extreme droughts and fires are can affect how the forest functions and change which tree species can integrate the forest system. With the acceleration of global change there’s an increasing likelihood that we will see positive feedback loops in which, rather than being able to repair itself, the forest loss becomes self-reinforced.”
By the year 2050, 10-47% of the Amazonian forests will be threatened by increasing disturbances, risking to cross a tipping point.
The study also examined the roles of biodiversity and local communities in shaping Amazonian forest resilience. They argue that successful approaches will depend on a combination of local and global efforts. This will include cooperation between Amazonian countries to end deforestation and expand restoration, while global efforts to stop greenhouse gas emissions mitigate the effects of climate change.
Boris Sakschewski, Potsdam Institute for Climate Impact research (PIK,) and one of the authors of the study, said:
“The Southeastern Amazon has already shifted from a carbon sink to a source –meaning that the current amount of human pressure is too high for the region to maintain its status as a rainforest over the long term.
“But the problem doesn’t stop there. Since rainforests enrich the air with a lot of moisture which forms the basis of precipitation in the west and south of the continent, losing forest in one place can lead to losing forest in another in a self-propelling feedback loop or simply ‘tipping’”.
The researchers identified five critical drivers connected to this tipping point:
global warming
annual rainfall amounts
the intensity of rainfall seasonality
dry season length
accumulated deforestation.
For each of these drivers they suggest safe boundaries to keep the Amazon resilient.
The impact of forest loss does not stop at the borders of the Amazon. The moisture transported via Amazons´ so called “flying rivers” is a critical part of the South American Monsoon and hence essential for rainfall in vast parts of the continent. Moreover, the Amazon as a whole stores carbon equivalent to 15-20 years of current human CO2 emissions. Amazon forest loss therefore further drives global warming and intensifies the consequences.
During the recent COP28 Climate Conference, the team published a set of policy briefs setting out steps that local, regional and global organisations need to take to prevent the Amazon from reaching a tipping point.
The study, Critical transitions in the Amazon forest system, is published in Nature.