A new study published today in the journal Nature suggests that extreme weather events such as wildfires and droughts will accelerate changes in stressed systems, leading to faster tipping points for ecological decline. natural sustainability.
The research team used computer modeling to study four threatened ecosystems to find out which factors might lead to a tipping point beyond which collapse is inevitable.
In some systems, adding new extreme events on top of other persistent stresses shortened the time of the predicted tipping point from the present time by as much as 80%.
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Ultimately, the authors say, a “perfect storm” of ongoing stress from factors such as unsustainable land use, agricultural expansion and climate change, combined with destructive events such as floods and fires, will conspire to rapidly endanger natural systems.
“More than a fifth of ecosystems globally are at risk of collapse,” said study co-leader Professor Simon Wilcock. “However, ongoing stress and extreme events interact to accelerate rapid changes that may be beyond our control. Once the tipping point is reached, it is too late.”
The team studied two lake ecosystems and two examples of forestry, including the historic collapse of civilization on Easter Island (Rapa Nui), widely believed to be the result of overpopulation and unsustainable tree-cover development.
The models for each ecosystem were run more than 70,000 times, adjusting variables each time. Even if the principal stresses remain constant, as many as 15% of collapses occur due to new stresses or extreme events.
In other words, even if ecosystems were managed more sustainably by keeping key stress levels such as deforestation constant, new stresses such as global warming and extreme weather events could still lead to collapse.
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The number of extreme climate events has increased since 1980 and will increase further even with 1.5°C global warming. Scientists also worry that ecosystem collapse could have knock-on effects on neighboring ecosystems.
“For the past two years, the world has come together around the climate and ecological crisis through the United Nations Conference on Climate Change and Biodiversity.
“But we should remember that the causes of the crisis are linked – they have collided – and failure to act on both issues could have dire consequences,” Mr Wilcock said.
Co-author Professor John Deering added: “Previous research on ecological tipping points has shown that, starting in the second half of the 21st century, there will be substantial social and economic costs. Our findings suggest that these costs are likely to occur.”
An example is the United Nations International Panel on Climate Change (IPCC) estimate of the tipping point for the Amazon forest by 2100. The new study suggests that the collapse could happen decades earlier than the IPCC predicted.
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For example, the Amazon forest is known to be threatened by deforestation. However, it’s not hard to imagine how global warming and extreme climate events such as droughts and wildfires could exacerbate this pressure.
This could reduce the Amazon’s ability to generate its own rainfall, making it drier and more vulnerable, leading to a vicious cycle for the ecosystem.
“All four ecosystems we studied showed the same overall results,” said co-author Dr Gregory Cooper. “This has potentially profound implications for how we think about future ecological risks.
“While it is currently impossible to predict how climate-induced tipping points and local anthropogenic impacts on ecosystems will be linked, our findings suggest that both are likely to reinforce each other. Any increasing pressure on ecosystems would be extremely harmful and could have dangerous consequences.”
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Brendan Montague is ecologist. This article is based on a press release from the Lausanne Research Center, the longest-running agricultural research facility in the world.
