According to a recent research, one in five countries are at risk of their ecosystems collapsing, threatening more than half of global GDP (US$42 trillion, or £32 trillion). When ecosystems collapse, they rapidly loose their structure and function, with dramatic changes to their size or extent, or the species that comprise them.
When mature forests collapse, they usually transition to more open woodland with scrub and grasses, depending on the grazing animals present and the climate. Pollution can quickly change lakes from clear waters writhing with salmon to green and turbid pools filled with toxic algae. These changes effectively mean that the original ecosystem has become locally extinct.
For humans, not all ecosystem changes are bad or recent. People have relied on modifying ecosystems for millennia to create new farmland. These environments are maintained in an artificially collapsed state for the benefit of maximizing a particular form of food and fiber. Further degradation within an already simplified ecosystem should at least be relatively straightforward to monitor and manage. The real dangers come from unplanned collapse, the unintended consequences of over-stressing an ecosystem that was near-natural and not dominated by humans.
Natural ecosystems can resist stresses from human actions or the climate for a long time but after a while, these stresses drive positive feedback loops that push the system over a tipping point. We know that the risk of ecosystems collapsing today is heightened by intense stresses from industry, farming and fishing that often act together and in tandem with global warming. Scientists are trying to simulate the effects of stress on ecosystems using computer models to gage the likelihood of collapse.
We do know that the duration of a collapse is relative to an ecosystem’s size. The bigger the ecosystem, the slower it will collapse because there are more species and connections to fail. There is also more chance that larger system collapses will be triggered at the same time in multiple places, as with the 2019-2020 wildfires in Australia. Recovering an ecosystem’s original state may be impossible because the external conditions that it depended upon—the climate regime or the soil properties—simply no longer exist.
For further information visit: https://phys.org/news/2020-11-one-fifth-ecosystems-danger-collapse.html