Large ecosystems, such as the Amazon rainforest, will collapse and disappear alarmingly quickly, once a crucial tipping point is reached, according to calculations based on real-world data.
Writing in Nature Communications (10.1038/s41467-020-15029-x), researchers from Bangor University, Southampton University and The School of Oriental & African Studies, University of London, reveal the speed at which ecosystems of different sizes will disappear, once they have reached a point beyond which they collapse - transforming into an alternative ecosystem.
For example, once the 'point of no return' is reached, the iconic Amazon rainforest could shift to a savannah-type ecosystem with a mix of trees and grass within 50 years, according to the work.
Some scientists argue that many ecosystems are currently teetering on the edge of this precipice, with the fires and destruction both in the Amazon and in Australia.
"Unfortunately, what our paper reveals is that humanity needs to prepare for changes far sooner than expected," says joint lead author Dr Simon Willcock of Bangor University's School of Natural Sciences.
"These rapid changes to the world's largest and most iconic ecosystems would impact the benefits which they provide us with, including everything from food and materials, to the oxygen and water we need for life."
What can be done to slow these collapses?
Ecosystems made up of a number of interacting species, rather than those dominated by one single species, may be more stable and take longer to shift to alternative ecosystem states. These provide opportunities to mitigate or manage the worst effects, say the authors. For example, elephants are a termed a 'key stone' species as they have a disproportionately large impact on the landscape - pushing over trees, but also dispersing seeds over large distances. The authors state that the loss of key stone species, such as this, would lead to a rapid and dramatic change in the landscape within our lifetime.
"This is yet another strong argument to avoid degrading our planet's ecosystems; we need to do more to conserve biodiversity," says Dr Gregory Cooper, School of Oriental & African Studies, University of London.
Prof John Dearing from Geography and Environment at Southampton University says:
"We intuitively knew that big systems would collapse more slowly than small ones - due to the time it takes for impacts to diffuse across large distances. But what was unexpected was the finding that big systems collapse much faster than you might expect - even the largest on Earth only taking possibly a few decades."