Across the world, rainforests are becoming savanna or farmland, savanna is drying out and turning into desert, and icy tundra is thawing. Indeed, scientific studies have now recorded “regime shifts” like these in more than 20 different types of ecosystem where tipping points have been passed. Across the world, more than 20% of ecosystems are in danger of shifting or collapsing into something different.
These collapses might happen sooner than you’d think. Humans are already putting ecosystems under pressure in many different ways – what we refer to as stresses. And when you combine these stresses with an increase in climate-driven extreme weather, the date these tipping points are crossed could be brought forward by as much as 80%.
This means an ecosystem collapse that we might previously have expected to avoid until late this century could happen as soon as in the next few decades. That’s the gloomy conclusion of our latest research, published in Nature Sustainability.
Human population growth, increased economic demands, and greenhouse gas concentrations put pressures on ecosystems and landscapes to supply food and maintain key services such as clean water. The number of extreme climate events is also increasing and will only get worse.
What really worries us is that climate extremes could hit already stressed ecosystems, which in turn transfer new or heightened stresses to some other ecosystem, and so on. This means one collapsing ecosystem could have a knock-on effect on neighbouring ecosystems through successive feedback loops: an “ecological doom-loop” scenario, with catastrophic consequences.
How long until a collapse?
In our new research, we wanted to get a sense of the amount of stress that ecosystems can take before collapsing. We did this using models – computer programs that simulate how an ecosystem will work in future, and how it will react to changes in circumstance.
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