Amazon near tipping point of shifting from rainforest to savannah, study suggests

The Amazon rainforest may be nearing a critical tipping point that could see the biologically rich and diverse ecosystem transformed into a grassy savannah.

The fate of the rainforest is crucial to the health of the planet because it is home to a unique array of animal and plant life, stores a huge amount of carbon and strongly influences global weather patterns.

Scientists say that about three quarters of the rainforest is showing signs of "resilience loss" -- a reduced ability to recover from disturbances like droughts, logging and fires. Their study is based on month-to-month observations of satellite data from the past 20 years that has mapped the biomass (the area's organic material) and the greenness of the forest to show how it has changed in response to fluctuating weather conditions.

This decreasing resilience since the early 2000s is a warning sign of irreversible decline, the authors said. While it isn't possible to tell exactly when the transition from rainforest to savannah might happen, once it was obvious, it would be too late to stop.

"It's worth reminding ourselves that if it gets to that tipping point and we commit to losing the Amazon rainforest, then we get a significant feedback to global climate change," Timothy M. Lenton, one of the authors of a new study and a director of the Global Systems Institute at the University of Exeter in the United Kingdom, told a news briefing.