Thanks to their large size, giant ecosystems such as the Amazon rainforests or the oceans are relatively impervious to environmental stress compared to smaller ones. Or so we tend to think.
However, a new study published in the journal Nature disproves this assumption. A larger and more complex ecosystem may be more prone to sudden collapse than a smaller one once environmental and climatic factors have passed a tipping point.
A team of researchers behind the study came to this conclusion after examining the relationship between the size of an ecosystem and the speed with which it collapses in dramatic "regime change." Their findings have yielded disturbing ideas.
"Regime changes can abruptly affect hydrological, climatic and terrestrial systems, leading to degraded ecosystems and impoverished societies," the authors write. "Large systems tend to change more slowly than small systems but disproportionately faster," they add, based on results from five computer models.
Even in human life, a vast ecosystem like that of the Amazon could fall apart. Dramatic changes in large ecosystems around the globe could “occur on 'human' timescales of years and decades, meaning that the collapse of large vulnerable ecosystems, such as the Amazon rainforest and the coral reefs of the Caribbean, may take only a few decades to complete. once it is activated ”, warn the scientists.
Initially, as can be expected, the larger and more biologically complex ecosystems are more resistant than the smaller and simpler ones. However, past a point of no return, they collapse faster as a result of a devastating effect on all their constituent parts.
A vast ecosystem like the Amazon rainforests could collapse in just half a century, while stressed coral reefs in the Caribbean could collapse in just a decade and a half.
Impressed by their scale, size, and geological age, we can be misled into thinking that large ecosystems are extremely resilient and can recover from the ravages of environmental stress. However, such an illusion of permanence is deceptive, experts warn.
"Humanity now needs to prepare for changes in ecosystems that are faster than we had previously envisioned through our traditional linear view of the world, including the largest and most iconic ecosystems on Earth and the socio-ecological systems they support," they say.
You've probably heard that our oceans have turned into plastic soup, but in fact, of all the plastic that enters Earth's oceans each year, only 1% has been observed to float on the surface.
So where is the rest?
This "lost" plastic has been a long-standing scientific question. To date, the search has focused on ocean gyres such as the Great Pacific Garbage Patch, the water column (the part of the ocean between the surface and the seabed), the ocean floor, and the stomachs of marine life.
But our new research suggests that plastic from the ocean is transported back to shore and is permanently pushed onto land away from the water's edge, where it often becomes trapped in vegetation.