Writing in the journal Trends in Ecology and Evolution, scientists from the University of Adelaide, along with U.S. and British colleagues, argue that global-scale ecological tipping points are unlikely and that ecological change over large areas seem to follow a more gradual, smooth pattern.
"This is good news because it says that we might avoid the doom-and-gloom scenario of abrupt, irreversible change," Barry Brook, lead author of the paper and Director of Climate Science at the University of Adelaide, said. "A focus on planetary tipping points may both distract from the vast ecological transformations that have already occurred, and lead to unjustified fatalism about the catastrophic effects of tipping points."
The scientists say they refute recent efforts to define "planetary tipping points" -- critical levels of biodiversity loss or land-use change that would have global effect -- often presented as fact to policy makers.
"An emphasis on a point of no return is not particularly helpful for bringing about the conservation action we need," Brook said in a university release Thursday..
A planetary tipping point, the authors suggest, could theoretically occur if ecosystems across Earth respond in similar ways to the same human pressures, or if there are strong connections between continents that allow for rapid diffusion of impacts across the planet.
"These criteria, however, are very unlikely to be met in the real world," Brook said. "First, ecosystems on different continents are not strongly connected. Second, the responses of ecosystems to human pressures like climate change or land-use change depend on local circumstances and will therefore differ between localities."
The four principal drivers of terrestrial ecosystem change -- climate change, land-use change, habitat fragmentation and biodiversity loss -- are unlikely to induce global tipping points, the researchers said.