Drivers of a potential planetary-scale critical transition (credit: Anthony D. Barnosky et al./Nature)
Using scientific theories, toy ecosystem modeling and paleontological evidence as a crystal ball, 21 scientists predict we’re on a much worse collision course with Mother Nature than currently thought.
In Approaching a state-shift in Earth’s biosphere, a paper just published in Nature, the authors, whose expertise spans a multitude of disciplines, suggest our planet’s ecosystems are careenng towards an imminent, irreversible collapse.
Earth’s accelerating loss of biodiversity, its climate’s increasingly extreme fluctuations, its ecosystems’ growing connectedness, and its radically changing total energy budget are precursors to reaching a planetary state threshold or tipping point.
Once that happens, which the authors predict could be reached this century, the planet’s ecosystems, as we know them, could irreversibly collapse in the proverbial blink of an eye.
“The last tipping point in Earth’s history occurred about 12,000 years ago when the planet went from being in the age of glaciers, which previously lasted 100,000 years, to being in its current interglacial state. Once that tipping point was reached, the most extreme biological changes leading to our current state occurred within only 1,000 years. That’s like going from a baby to an adult state in less than a year,” explains Simon Fraser University Professor Arne Mooers, one of this paper’s authors. “Importantly, the planet is changing even faster now.”
He stresses, “The odds are very high that the next global state change will be extremely disruptive to our civilizations. Remember, we went from being hunter-gatherers to being moon-walkers during one of the most stable and benign periods in all of Earth’s history.
“Once a threshold-induced planetary state shift occurs, there’s no going back. So, if a system switches to a new state because you’ve added lots of energy, even if you take out the new energy, it won’t revert back to the old system. The planet doesn’t have any memory of the old state.”
These projections contradict the popularly held belief that the extent to which human-induced pressures, such as climate change, are destroying our planet is still debatable, and any collapse would be both gradual and centuries away.
This study concludes we better not exceed the 50 per cent mark of wholesale transformation of Earth’s surface or we won’t be able to delay, never mind avert, a planetary collapse.
We’ve already reached the 43 per cent mark through our conversion of landscapes into agricultural and urban areas, making Earth increasingly susceptible to an environmental epidemic.
“In a nutshell, humans have not done anything really important to stave off the worst because the social structures for doing something just aren’t there,” says Mooers. “My colleagues who study climate-induced changes through the earth’s history are more than pretty worried. In fact, some are terrified.”
Backgrounder: Study predicts imminent irreversible planetary collapse
Coming from Chile, Canada, Finland, the United Kingdom, Spain and the United States, the authors of this paper initially met at the University of California Berkeley in 2010 to hold a trans-disciplinary brainstorming session.
They reviewed scores of theoretical and conceptual bodies of work in various biological disciplines in search of new ways to cope with the historically unprecedented changes now occurring on Earth.
In the process they discovered that:
Human-generated pressures, known as global-scale forcing mechanisms, are modifying Earth’s atmosphere, oceans and climate so rapidly that they are likely forcing ecosystems and biodiversity to reach a critical threshold of existence in our lifetime.
“Global-scale forcing mechanisms today “include unprecedented rates and magnitudes of human population growth with attendant resource consumption, habitat transformation and fragmentation, energy production and consumption, and climate change,” says the study.
Human activity drives today’s global-scale forcing mechanisms more than ever before. As a result, the rate of climate change we are seeing now exceeds the rate that occurred during the extreme planetary state change that tipped Earth from being in a glacial to an interglacial state 12,000 years ago. You have to go back to the end of the cataclysmic falling star, which ended the age of dinosaurs, to find a previous precedent.
The exponentially increasing extinction of Earth’s current species, dominance of previously rare life forms and occurrence of extreme climate fluctuations parallel critical transitions that coincided with the last major planetary transition.
When these sorts of perturbations are mirrored in toy ecosystem models, they tip these systems quickly and irreversibly.
The authors recommend governments undertake five actions immediately if we are to have any hope of delaying or minimizing a planetary-state-shift. Arne Mooers, an SFU biodiversity professor and a co-author of this study, summarizes them as follows.
“Society globally has to collectively decide that we need to drastically lower our population very quickly. More of us need to move to optimal areas at higher density and let parts of the planet recover. Folks like us have to be forced to be materially poorer, at least in the short term. We also need to invest a lot more in creating technologies to produce and distribute food without eating up more land and wild species. It’s a very tall order.”
Ref.: Anthony D. Barnosky et al., Approaching a state shift in Earth’s biosphere, Nature, 2012, DOI: 10.1038/nature11018