Earth’s ecosystems may be collapsing much faster than scientists thought, a new study of our planet’s warming climate warns.
According to the research, more than a fifth of the world’s potentially catastrophic tipping points — such as the melting of Arctic permafrost, the collapse of the Greenland ice sheet and the sudden transformation of the Amazon rainforest into savanna — could occur as early as 2038. .
In climatology, a “tipping point” is the threshold above which a local climate system, or “tipping element”, changes irreversibly. For example, if the Greenland ice sheet collapsed, that would also reduce snowfall in the northern part of the island, rendering large parts of the ice sheet irreparable.
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But the science behind these dramatic transformations is poorly understood and often based on oversimplified models. Now, a new attempt to understand their inner workings, published June 22 in the journal Nature, has revealed that they may be happening much sooner than we thought.
“More than a fifth of the world’s ecosystems are at risk of collapse,” study co-author Simon Willcock, a professor of sustainability at Bangor University in the UK, said in a statement. “However, ongoing tensions and extreme events work together to accelerate rapid changes that we may not be able to control. Once these reach a tipping point, it will be too late.”
Contrary to the established link between burning fossil fuels and climate change, the study of tipping points is a young and controversial science.
To understand how rising temperatures and other environmental stressors can cause complex ecosystems to collapse, scientists use computer models to simplify ecosystem dynamics, allowing them to predict the fate of those ecosystems — and when their tipping points might be reached.
But if these simulations miss a key element or interaction, their predictions could fail for decades. For example, the Intergovernmental Panel on Climate Change (the United Nations’ main body for evaluating climate science) said in its most recent report that the Amazon rainforest could reach a tipping point that will turn it into a savanna by 2100.
The researchers behind the new study say this prediction is too optimistic.
According to the researchers, most tipping point studies build the math into their models to focus on one predominant cause of collapse, for example, deforestation in the Amazon rainforest. However, ecosystems are not faced with just one problem, but rather with a swarm of destabilizing factors that reinforce each other. For example, the Amazon also has to deal with rising temperatures, soil degradation, water pollution and water stress.
To investigate how these elements interact and whether these interactions can, in fact, hasten a system’s demise, the scientists behind the new study built computer models of two lake and two forest ecosystems (including one that modeled the collapse of civilization on Easter Island). ) and ran them over 70,000 times while adjusting the variables throughout.
After testing their systems in multiple modes — single-cause, multi-cause, and all-cause plus the introduction of random noise to mimic fluctuations in climate variables — the scientists came to some disturbing findings: multiple causes of collapse working together brought the abrupt transformation of some systems up to 80% closer to the present.
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And even when the main cause of collapse was not allowed to increase with time, 15% of collapses happened purely because of the new elements.
“Our main finding from four ecological models was that ecosystems could collapse 30-80% sooner, depending on the nature of additional stress,” study co-author John Dearing, a professor of physical geography at Southampton University in the UK, said in a paper. email to Live Science. “So if previous tipping points were predicted for 2100 (i.e. 77 years from now), we suggest that these could happen 23 to 62 years earlier, depending on the nature of the tensions.”
This means significant social and economic costs of climate change could come much sooner than expected, giving governments even less time to respond than first thought.
“This may have profound implications for our perception of future ecological risk,” study co-author Gregory Cooper, a climate systems researcher at the University of Sheffield in the UK, said in the statement. “While it is currently not possible to predict how climate-induced tipping points and the effects of local human actions on ecosystems will be linked, our findings show that both have the potential to reinforce the other. Any increasing pressure on ecosystems will be extremely harmful and could have dangerous consequences.”