- The Amazon rainforest’s ecosystem could collapse very rapidly, in only 50 years, if climate change reaches a tipping point, a new study suggests.
- Large ecosystems would collapse disproportionately quickly compared to smaller ecosystems, the researchers’ computer simulations have found.
- However, a scientists not involved in the study has said that their ‘conclusions are not supported by the data analysed’.
Large ecosystems such as the Amazon rainforest could collapse in less than 50 years once a crucial tipping point is reached, scientists have claimed. Their predictions are based on computer simulations using real-world data gathered from more than 40 natural environments.
Writing in Nature Communications, the researchers said some of these ecosystems are collapsing at a “significantly faster rate” than thought and, when put under stress, could transform into “an alternative ecosystem”.
For example, they said, the Amazon rainforest, which is around 5.5 million square kilometres, could shift to “a savannah-type ecosystem with a mix of trees and grass” in just 49 years while the Caribbean coral reefs, approximately 20,000 square kilometres, would become bleached and sparsely populated in just 15 years.
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Dr Simon Willcock, of Bangor University’s School of Natural Sciences in Wales, and joint lead author on the study, said: “Unfortunately, what our paper reveals is that humanity needs to prepare for changes far sooner than expected.
“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.”
The researchers, including teams from Bangor University, Southampton University and the School of Oriental & African Studies, University of London, studied data on the transformations of four land, 25 marine and 13 freshwater ecosystems.
Using computer modelling, they found that, while larger ecosystems took longer to collapse, their breakdown occurred disproportionately quickly compared with the smaller systems.
Prof John Dearing, from Geography and Environment at Southampton University, who led the research, said: “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.”
Commenting on the research, James Crabbe, a professor of biochemistry, University of Bedfordshire, who was not involved in the study, described the study as “a thorough and well-researched paper” that brings together “observations with five computational models”.
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But Dr Erika Berenguer, a senior research associate at University of Oxford and Lancaster University, who was also not involved in the study, said its conclusions are not supported by the data analysed.
For example, she said, the claim that the Amazon will become a “savannah-type ecosystem” was not tested in the paper.
“The authors use data from only four terrestrial systems, none of which is a tropical rainforest, but still claim that the Amazon, the largest rainforest on the planet, will experience a dieback in just 50 years,” she said. “While there is no doubt that the Amazon is at great risk and that a tipping point is likely, such inflated claims do not help either science or policy-making.”
Reader Q&A: Do we really know what climate change will do to our planet?
Asked by: Jennifer Cowsill, via email
There is no doubt that greenhouse gas emissions caused by humans are changing our climate, resulting in a progressive rise in global average temperatures. The scientific consensus on this is comparable to the scientific consensus that smoking causes lung cancer.
Our climate is a hugely intricate system of interlinking processes, so forecasting exactly how this temperature increase will play out across the globe is a complex task. Scientists base their predictions on powerful computer models that combine our understanding of climatic processes with past climate data.
Many large-scale trends can now be calculated with a high degree of certainty: for instance, warmer temperatures will cause seawater to expand and glaciers to melt, resulting in higher sea levels and flooding. More localised predictions are often subject to greater uncertainty.