New Studies Warn of Irreversible Rainforest Decline

Two major rainforests—the Amazon and the Congo Basin—are showing signs of accelerating ecological decline, according to separate studies published in leading scientific journals. Both point to deforestation and inadequate land management as the driving forces behind a loss of resilience that could have consequences far beyond the forests themselves.

A seedling growing amid Congo Basin deforestation, showing a fragile balance between forest loss and resilience near a tipping point. AI generated picture.

Amazon's rainfall system under threat

Research from the Potsdam Institute for Climate Impact Research (PIK) has found that the Amazon rainforest is significantly more vulnerable to deforestation than earlier models suggested. The study, published in Nature, identifies a self-reinforcing dynamic at the heart of the problem: the Amazon generates up to half of its own rainfall through the water vapour released by its trees. Remove enough trees, and that system begins to break down.

'Deforestation makes the Amazon far less resilient than we previously anticipated. It dries out the atmosphere and weakens the forest's own rainfall generation,' said Nico Wunderling, PIK scientist and lead author of the study.

The researchers estimate that total deforestation of between 22% and 28% could push the Amazon past a tipping point from which recovery is no longer possible. Current deforestation levels already stand at 17%–18%.

The effects would not be confined to the forest. Reduced rainfall across South America would affect agricultural production from Bolivia to the Río de la Plata basin in Argentina. The study highlights restoration as a key lever for strengthening resilience, citing Brazil's plan to restore around 12 million hectares as a significant example of the ambition required.

Congo Basin's carbon storage at risk

A study published in Nature Communications draws equally serious conclusions about the Congo Basin. Researchers at CTrees analysed carbon stocks across the region's approximately 200 million hectares from 1990 to 2020, finding that managed forests were responsible for 98.7% of the region's net carbon sink over that period.

Unmanaged forest, which holds 54% of the basin's total above-ground carbon (AGC), was carbon neutral across the same timeframe—and is increasingly exposed to loss through smallholder agriculture and urban expansion.

'Currently, nearly half of the Congo Basin's forest carbon is stored in unmanaged areas, placing it at significant risk of rapid loss from small-scale clearings,' said lead author Le Bienfaiteur Sagang, research scientist at CTrees.

The data highlights the difference active management makes. Selectively logged forests held an average of 7.5% less AGC than old-growth forests. Areas affected by slash-and-burn agriculture showed up to 50% less carbon density. The Congo Basin as a whole stores an estimated 32.3 billion tonnes of carbon—around 21% of all carbon stocks in tropical moist forests worldwide.

Taken together, the two studies reinforce a clear message: forest resilience does not happen passively. It depends on informed, sustained, and science-led stewardship.