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article imageWorld needs to be ready for irreversible reshaping of ecosystems

By Karen Graham     Mar 10, 2020 in Environment
Irreversible changes may start reshaping the world’s ecosystems as soon as the next few years—much sooner than previously thought.
Researchers from Bangor University, Southampton University and The School of Oriental & African Studies at the University of London, in a new study published in Nature Communications on March 10, are warning that humanity needs to prepare for changes to our environment much sooner than expected.
Drawing on pre-existing studies and computer modeling, the researchers examined a number of Earth system tipping points in 40 different ecosystems, including forests, coral reefs, and marshes - with sizes varying from small ponds to marine ecosystems
Old boreal forest settlement on the René-Levasseur island  Manicouagan  Québec.
Old boreal forest settlement on the René-Levasseur island, Manicouagan, Québec.
Colocho (CC BY-SA 3.0)
What they found is very surprising. It seems the apparent stability of the world’s largest ecosystems is “a deceptive guide to the potential speed of their collapse.”
To put this finding another way - Large ecosystems take longer to collapse than smaller ones, owing to their sheer size. However, the rate at which large ecosystems become vulnerable to collapse is significantly faster than the rate of change of smaller systems.
As the study explains, this is simply because large ecosystems are made up of multiple small systems and species. A good example of this is a study done in 2015 by graduate student Stephen De Lisle and Professor Locke Rowe of the University of Toronto's Department of Ecology & Evolutionary Biology.
In this particular study, the researchers wanted to find out why 30 to 40 percent of the world's approximately 7,000 species of amphibians were in danger of extinction. They wanted to understand why some species were able to survive while others were disappearing.
As it turns out, it has a lot to do with sexual dimorphism and the fact that many scientists look at amphibians as "canaries in a coal mine," with declines in this species an indicator that other plants or animals may be in danger of extinction.
Brazilian farmer Helio Lombardo Do Santos and a dog walk through a burnt area of the Amazon rainfore...
Brazilian farmer Helio Lombardo Do Santos and a dog walk through a burnt area of the Amazon rainforest, near Porto Velho, Rondonia state, Brazil, on August 26, 2019
CARL DE SOUZA, AFP
Even though different ecological compartments provide resilience against stress in the initial phase of the transformation, once a certain threshold is crossed, the same modularity contributes to an acceleration of the system’s collapse.
The authors write: “We must prepare for regime shifts in any natural system to occur over the ‘human’ timescales of years and decades, rather than multi-generational timescales of centuries and millennia.” Actually, the researchers found that huge ecosystems that have existed for thousands of years could collapse in as little as 50 years.
Under its Reef 2050 Plan  Australia is fighting the effects of an unprecedented two straight years o...
Under its Reef 2050 Plan, Australia is fighting the effects of an unprecedented two straight years of coral reef bleaching on its iconic Great Barrier Reef
Handout, BIOPIXEL/AFP/File
Pause for a moment and think of some of the world's large, iconic ecosystems - The Amazon Rainforest, Canada's Boreal forests, Antarctica, Australia's Great Barrier Reef, just to name a few. All of these examples are large ecosystems, made up of many smaller ecological compartments -each with its own system teeming with plants and animals.
According to the study, "With the frequency of regime shifts predicted to increase in association with climate change and environmental degradation, developing a general understanding into the spatial and temporal dynamics of shifts would help to anticipate the nature and timing of potential impacts."
And just so you, the reader knows - According to the study, the Amazon Rain Forest will shift over a period of 49 years. Studies have already shown a declining rate of carbon sequestration, and there is growing evidence that further deforestation and degradation of the feedback between moisture formation and vegetation coverage may lead to a system-wide tipping point as soon as 2021.
More about Climate change, irreversible change, large ecosystems, Regime shifts, Ecosystem collapse
 
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