A worrying sign of ecosystem stress

Getting your Trinity Audio player ready...

The world’s largest tropical rainforest is showing troubling signs of weakening resilience. A new study published in the journal Proceedings of the National Academy of Sciences (PNAS) has found that 37% of mature forest in the Amazon Rainforest is demonstrating “critical slowing down” in its recovery from drought between 2001 and 2019. (Delft University of Technology Research)
According to coverage by The Guardian, the findings suggest the rainforest could be approaching a tipping point if droughts become more frequent and intense. (The Guardian)

“It is a warning sign that a tipping point can be reached in the future if these droughts continue to increase and get more intense,” said lead author Johanna Van Passel. – The Guardian

The study’s key takeaway: repeated, increasingly intense droughts appear to be draining the forest’s ability to bounce back.

What is the study and where is it from?

The research, titled “Critical slowing down of the Amazon forest after increased drought occurrence”, was published in May 2024 in PNAS. (Delft University of Technology Research)
The lead author is Johanna Van Passel of KU Leuven in Belgium, along with co-authors from universities in Brazil, Germany and the Netherlands. (Delft University of Technology Research)
Using monthly satellite observations (the Moderate Resolution Imaging Spectroradiometer, MODIS) from 2001 to 2019, they tracked vegetation indices across grid cells of 5 × 5 km in the Amazon region. (Delft University of Technology Research)

Their method focused on “temporal autocorrelation” (TAC): essentially how slowly the vegetation returns from a disturbance. A rising TAC indicates slower recovery — a hallmark of what ecologists call “critical slowing down” or diminished resilience. (Delft University of Technology Research)

They also disentangled different drought metrics — frequency, intensity and duration — and found that intensity of drought events mattered more than mere frequency or duration for triggering slower recovery. (Delft University of Technology Research)

In sum: the study originates from a European–Brazilian scientific collaboration, published in a leading journal, and uses large-scale remote sensing analysis to assess forest recovery over nearly two decades.

What researchers say — resilience still there, but under strain

The authors are cautiously optimistic: they emphasise that the Amazon is not yet past a threshold of irrevocable collapse, but the warning lights are flashing.

• Van Passel notes that the entire forest is not yet showing slowed recovery — the trend is uneven across the basin. (Delft University of Technology Research)
• However, in areas especially the south-eastern Amazon — previously heavily deforested and degraded — the signals of slowing recovery are strongest. (The Guardian)
• The authors caution that their satellite-based analysis measures canopy greenness and productivity, so may underestimate stress occurring at under-canopy or tree-level scales. (Delft University of Technology Research)
• From the Guardian article: “Trees are the last part of the ecosystem to show tipping points… if we are already seeing a tipping point getting closer at this macro forest level, then it must be getting worse at a micro level.” (The Guardian)
• The paper calls for urgent action: reducing deforestation, protecting remaining intact forests, and rapidly cutting greenhouse gas emissions to avoid further erosion of forest resilience. (The Guardian)

In short: the forest still shows impressive bounce-back in many areas, but that capacity is shrinking — especially where human impacts and drought stress combine.

What the Guardian and media source highlight

The Guardian’s coverage summarises the study and its implications for global climate and biodiversity. Key points include:

• More than one-in-three of the mature Amazon forest is showing slower recovery from drought. (The Guardian)
• The study builds on a backdrop of four supposedly “once-in-a-century” droughts in less than 20 years. (The Guardian)
• Drought intensity was more strongly correlated with slower recovery than just more frequent droughts. (The Guardian)
• The south-east of the Amazon — where deforestation has been high — is highlighted as a hotspot of vulnerability. (The Guardian)
• The article emphasises the global ramifications: the Amazon is not just Brazil’s forest, it is “the lungs of the planet,” a vast carbon sink, and a climate-regulating system. (The Guardian)

The media framing underscores urgency: the study is seen as a red flag for the Amazon’s ability to continue providing global ecosystem services — especially carbon storage and rainfall recycling.

“Trees are the last part of the ecosystem to show tipping points… if we are already seeing a tipping point getting closer at this macro-forest level, then it must be getting worse at a micro level.” –The Guardian

What conservation organisations are saying

Several NGOs and conservation groups are weighing in, underscoring concern and calling for action.

Greenpeace
Greenpeace has been vocal about the drought impacts in the Amazon:

• In October 2023 it described massive die-offs of fish and dolphins, rivers drying, Indigenous and riverine communities cut off. (Greenpeace)
• In September 2024 it staged a protest banner reading “Who Pays?” on exposed river sandbanks in the Amazon basin, attributing the damage to fossil-fuel-driven climate change. (Devdiscourse)
• Greenpeace calls for zero deforestation, immediate support for affected communities, and action on fossil-fuel emissions. (Greenpeace)

World Wildlife Fund (WWF)
While not reacting specifically to the PNAS paper (in publicly-available material), WWF emphasises the importance of the Amazon rainforest and warns the ecosystem is nearing irreversible tipping.

• WWF states the Amazon holds nearly a third of all tropical rainforest, supports huge biodiversity, and is critical to global climate. (WWF)
• In The Independent, WWF warned the Amazon may be nearing a “point of no return” driven by drought, deforestation and fire. (The Independent)

Rainforest Foundation US

• The Foundation notes that extreme drought and rising heat are pushing the Amazon “closer toward ecological collapse,” affecting rivers, wildlife and Indigenous communities. (Rainforest Foundation US)

Other groups such as Conservation International, The Nature Conservancy and Amazon Watch did not feature prominently in readily-available media coverage on this exact study, though their broader work on Amazon conservation is well established.

Together, the voices of NGOs converge on a similar message: the Amazon is under accelerating stress; protecting it is a global priority.

“We want to send a message that climate change is already affecting even the world’s largest rainforest and drying up its rivers.” – Romulo Batista, Greenpeace Brazil

Why this matters — ecosystem, climate and global stakes

The Amazon rainforest is one of the planet’s most consequential ecosystems for four key reasons:

• Carbon storage and climate regulation: The Amazon accounts for a very large share of global tropical forest carbon sequestration. Its degradation risks turning it from carbon sink to carbon source. (Delft University of Technology Research)
• Biodiversity hotspot: The forest houses an estimated 15 000 tree species, hundreds of mammal and bird species, and myriad amphibians, insects and plants. (Delft University of Technology Research)
• Hydrological cycle: The forest helps regulate rainfall both locally and regionally; its leaf transpiration drives “flying rivers” of moisture that affect much of South America. (Phys.org)
• Human communities: Indigenous peoples and river-based communities rely on the forest and its rivers for food, culture, transport and livelihoods; prolonged drought spells acute hardship. (Greenpeace)

In practical terms, the slowing-recovery of large tracts of the Amazon means that as droughts become more intense (and frequent) under climate change, the forest will take longer to bounce back — potentially leading to structural changes. Tree mortality could rise, canopy cover diminish, species composition shift, and forest might become more fire-prone or transition toward a more open (savanna-like) state.

The study explicitly warns that “intensity and frequency of droughts will very likely continue to increase due to climate change. It is therefore crucial that we try to protect the remaining resilience in most of the Amazon rainforest.” (growkudos.com)

Regional hotspots and the human dimension

The hurting is not evenly distributed. The study and media reporting highlight:

• The south-eastern Amazon (Brazil) shows the strongest signs of slowed recovery. That is also the region most impacted by deforestation, fragmentation and fires. (The Guardian)
• In these disturbed landscapes, the internal water-cycling of the forest is already weaker, making such areas more vulnerable to drought stress. (Delft University of Technology Research)
• On the human side: during recent droughts, rivers dropped to record lows, navigation became impossible for many communities, drinking-water supplies ran low, and wildlife die-offs of aquatic species occurred. (Greenpeace)

These human-forest feedbacks create a kind of vicious cycle: degraded forest → weaker rainfall/less transpiration → weaker recovery → greater drought vulnerability → more human/habitat stress → further degradation.

Caveats and scientific nuance

While the findings are alarming, the study includes important caveats that should temper interpretations:

• The slowed recovery signal (37% of mature forest) does not mean the entire Amazon is collapsing — the majority of the forest (≈63%) did not show clear slowing trends during the period studied. (Delft University of Technology Research)
• Satellite canopy indicators capture surface greenness/productivity but may not detect deeper stress such as root damage, under-canopy dynamics or delayed mortality. Van Passel notes the real situation “could be worse when you look at the scale of individual plants.” (Delft University of Technology Research)
• The concept of a “tipping point” is not deterministic — the study does not claim the Amazon will collapse imminently. But it uses established ecological theory (critical slowing down) to indicate increasing proximity to thresholds. (Delft University of Technology Research)
• The analysis covers up to 2019. Stressors since then — such as the 2022–2024 droughts, fires and deforestation surges — may have exacerbated the trends but are not captured in this dataset.

Implications and the road ahead

To policymakers and global leaders:
The study offers a clear signal that protecting the Amazon is not simply about stopping deforestation and fires (although those remain critical) — it is also about maintaining the forest’s resilience in a changing climate. That means:

• Rapidly reducing global greenhouse gas emissions so as to curb warming and reduce drought intensity/frequency.
• Strengthening measures to prevent forest degradation and fragmentation, especially in vulnerable zones like the south-eastern Amazon.
• Supporting Indigenous and local communities who are frontline defenders of intact forest and who bear disproportionate burdens of drought and habitat loss.
• Monitoring forest health, recovery rates and ecosystem stress using advanced remote sensing and ground-based networks.

For conservation and civil-society actors:
The findings provide scientific backing for urgent campaigns and action. Groups such as Greenpeace are emphasising the human and biodiversity impacts — stranded communities, dying dolphins, empty rivers. WWF and others are highlighting the tipping-point risk. Synergising these voices into actionable frameworks (e.g., commodity-supply chain reforms, finance for forest resilience, Indigenous rights) will be vital.

For global climate-ecosystem modelling:
The Amazon is a keystone system. If its resilience declines further, larger systemic risks emerge: less rainfall, shifting carbon dynamics, altered regional climate, feedbacks into global weather patterns. The 37% figure is significant not only for the Amazon but for how we understand tropical-forest responsiveness to climate change.

On the ground:
Communities in the Amazon are already experiencing the impacts. Drought means rivers too shallow for transport, fish kills, stranded Indigenous villages, health risks from contaminated water supplies. The human cost is measurable today — meaning the science is not just about future risk but real-time vulnerability.

“It is a warning sign that a tipping point can be reached in the future if these droughts continue to increase and get more intense.” – Johanna Van Passel, lead author

Conclusion

The new PNAS study raises a red-flag for the Amazon rainforest’s future. While the forest is not collapsing today, it is showing reduced capacity to recover from repeated droughts – especially in its more degraded zones. With climate change projected to bring more frequent and intense droughts, the window for preserving the Amazon’s full-functioning, carbon-storing, rainfall-recycling ecosystem is narrowing fast.

Protecting the Amazon is no longer just a conservation issue. It is a climate issue and a humanity issue. The resilience that forests have shown for millennia is being tested — and for more than a third of the mature Amazon, that test is turning into a struggle. If global leaders, conservation groups and local communities act decisively — by cutting emissions, halting deforestation, restoring degraded lands and supporting forest-dependent peoples — there is still hope. But the clock is ticking.