Extensive logging and burning may be pushing the Amazon’s rainforests towards a tipping point beyond which they will be a lot less resilient to environmental stresses such as climate change.
This stark assessment has been made by an international team of scientists who analyzed data from high-resolution satellite images and have concluded that over the past two decades around three quarters of the Amazon’s forests have been losing their ability to withstand stresses, including droughts and forest fires.
“That we see such a resilience loss in observations is worrying,” stresses Niklas Boers, a scientist at the Potsdam Institute for Climate Impact Research and the Technical University of Munich. Working with researchers from the University of Exeter in the United Kingdom, Boers and his colleagues have published their findings in a study.
“The Amazon rainforest is a home to a unique host of biodiversity, strongly influences rainfall all over South America by way of its enormous evapotranspiration, and stores huge amounts of carbon that could be released as greenhouse gases in the case of even partial dieback, in turn contributing to further global warming,” Boers explains. “This is why the rainforest is of global relevance.”
Other research teams have reached similar conclusions about the Amazon in recent years, but many of these conclusions were based on computer models. Boers and his colleagues relied instead on observational data for signs of changes in the forests’ resilience over the past few decades.
To evaluate the data, they used stability indicators previously applied to the ice sheet in Greenland, among other regions being impacted by climate change.
“These statistical indicators aim at predicting the approach of a system towards an abrupt change by identifying a critical slowing down of the system’s dynamics, for instance its reaction to weather variability,” the researchers explain in a statement.
“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 a weakening of the restoring forces that usually bring the system back to its equilibrium after perturbations.”
Needless to say, their findings are sobering. “We see continuously decreasing rainforest resilience since the early 2000s, but we cannot tell when a potential transition from rainforest to savanna might happen. When it will be observable, it would likely be too late to stop it,” Boers says.
Alarmingly, in many areas of the Amazon destabilization of local forests appears to be well underway. Once climate change begins to have its impacts felt even more strongly in these and other areas in coming decades, forests and their ecosystems will likely succumb without the ability to recover.
However, we can still give these embattled forests a fighting chance, the scientists stress. “[S]trongly limiting the logging, but also limiting global greenhouse gas emissions, is necessary to safeguard the Amazon,” notes Tim Lenton, director of the Global Systems Institute.
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