Amazon Rainforest Is Losing Resilience: New Evidence from Satellite Data Analysis

The Amazon rainforest, the world’s largest intact rainforest and an important global carbon store, has been steadily losing its resilience, leading to concern over its long-term survival.

Data analysis from high-resolution satellite images suggests that about three-quarters of the forest has been decreasing its ability to recover from perturbation since the early 2000s, which the scientists from the Potsdam Institute for Climate Impact Research and the University of Exeter see as a warning sign.

The new evidence, which is derived from advanced statistical analysis of satellite data changes in vegetation biomass and productivity, is now published in the journal Nature Climate Change (Boulton et al., 2022).

‘Reduced resilience — the capacity to recover from events such as droughts or fires – can raise the danger of Amazon rainforest extinction. It’s concerning that we observe such a loss of resilience in observations,’ says Potsdam researcher Niklas Boers, who performed the study in collaboration with academics from the University of Exeter in the United Kingdom.

Boers explains that the Amazon rainforest is home to a unique array of biodiversity, strongly influences rainfall throughout South America due to its enormous evapotranspiration, and stores enormous amounts of carbon that could be released in the event of even a partial dieback, thereby contributing to further global warming. Therefore, the rainforest is of global significance.

Climate Change: Too Late to See the Tipping Itself

Climate change is making it harder for the Amazon rainforest to survive, with hotter and drier conditions exacerbating annual droughts, wildfires, and other natural disasters. Recent studies indicate that Amazon may even reach a “tipping point” in the coming decades. At this point, further climate change could result in the Amazon becoming a carbon source instead of a carbon storage site.

Boers says: For decades, we’ve examined particular observational data for resilience changes. Since the early 2000s, rainforest resilience has been deteriorating, but we cannot predict a rainforest-to-savanna shift. But we don’t know when a possible change from rainforest to savanna might happen. When it is observable, it would likely be too late to stop it.

The research team used stability indicators that had previously been applied to the Greenland ice sheet and the Atlantic overturning circulation.

These statistical indicators aim to predict a system’s approach towards an abrupt change by identifying a critical slowing down of the system’s dynamics, for instance, its reaction to weather variability.

The analysis of two satellite data sets, representing biomass and the greenness of the forest, revealed the critical slowing down. This critical slowing down can be seen as weakening the restoring forces that usually bring the system back to equilibrium after perturbations.

A System’s Mean State Seldom Appears Stable

“While a system may appear stable when its mean state is considered, a closer examination of the data using unique statistical approaches might indicate resilience loss,” says Chris Boulton of the University of Exeter’s Global Systems Institute.

“Previous research based on computer simulations revealed that substantial areas of the Amazon can be committed to dieback before displaying a dramatic shift in the mean condition. Our observational investigation indicates that instability appears to begin in numerous regions.”

To establish the causes of the loss of resilience shown in the data, the scientists investigated the relationship between rainfall in a certain area of the Amazon, culminating in three ‘once-in-a-century drought occurrences in the region. Drier locations are shown to be more vulnerable than wetter ones.

“This is concerning because the IPCC models predict that the Amazon region would dry out due to human global warming,” adds Boers. Another consideration is the distance from highways and communities where people may enter the forest. The analysis reveals that locations near human land use are more vulnerable.

“Our innovative empirical data analysis adds to the concerns regarding the forest’s resilience, particularly in the near future,” says Tim Lenton, Director of the Global Systems Institute.

“It demonstrates that significantly controlling logging while simultaneously decreasing global greenhouse gas emissions is required to protect the Amazon.”