Once a tipping point is reached, the world’s largest ecosystems could collapse at accelerated speed—the Amazon could take 49 years and the Caribbean coral reef just 15 years, scientists have warned.
Researchers writing in Nature Communications say that “regime shifts” tend to have a disproportionate effect on larger ecosystems. This means that though they tend to shift more slowly than smaller ecosystems, they do so disproportionately faster.
For the study, the researchers analyzed empirical data collected from 42 ecosystems from across the world—four terrestrial, 25 marine and 13 freshwater-based, and then confirmed their findings using five separate computational models.
The ecosystems analyzed ranged in size from the Paul and Peter lakes in Michigan (0.007 square miles, or 0.020 square kilometers) to the Sahel in north Africa (3,600,000 square miles, or 9,400,000 square kilometers). From these, they were able to make a second set of projections predicting how long it would take ecosystems like the Amazon to collapse once a tipping point has been reached.
Ultimately the study shows that, once triggered, these shifts take place over “human” timescales of years and decades rather than “generational” timescales of centuries and millennia. As for the Amazon, the models project it could take just 49 years once it passes the tipping point—which some predict could take place as soon as 2021.
“The Amazon rainforest has been around for hundreds of millions of years—the fact it could be lost in less than 50 years really surprised me,” Dr Simon Willcock of Bangor University’s School of Natural Sciences in the U.K. told Newsweek.
“Ultimately, if we do not stop the decline of our ecosystems then we will lose them,” said Wilcock. “We depend on our ecosystems for many aspects of our lives and so the declines need to be urgently addressed.”
The researchers warn that this shows we need to prepare for these changes to take place on a much faster timescale than we might think. It shows that it does not matter how long a particular ecosystem has been in place. Even the oldest and apparently most established can disintegrate within a human lifetime.
The good news is that these changes are not irreversible—though they may be very hard to reverse, said Wilcock.
He compares the situation to a runaway boulder rolling down the hill. It is possible to push the boulder back to the top of the hill but it is easier to stop it from rolling down in the first place, or try to catch it before it gets close to the bottom.
“This is what we need to do. We need to better protect our ecosystems and use resources more sustainably to prevent them collapsing. We also need to monitor our ecosystems closely and if they do show signs of collapse, we need to act fast!”
John Dearing, Professor in Physical Geography at the University of Southampton, U.K., says pulling back from the brink through reducing our impact on ecosystems has to be a major priority.
“It’s a stark warning about disturbing ecosystems through deforestation, overgrazing, overfishing, fertilizer and pesticide runoff, and global warming—to a point where they reach their limits and collapse,” he said.