Cropped version of illustration by Cheng (Lily) Li

In a paper published this week in Nature, an international team of scientists, including three SFI researchers, examines the evidence for a possible state shift in the Earth’s biosphere, warning that population growth, destruction of ecosystems, and climate change may be driving Earth toward sudden, irreversible, and destructive changes.

SFI External Professors Jim Brown, Pablo Marquet, and John Harte are among the paper’s co-authors.

Read the paper in Nature (June 6)

Read the UC Berkeley news release (June 6)

Read the New York Times article quoting Jim Brown (June 7, 2012)

Read the Wired article (June 6, 2012)

State shifts, popularly known as “tipping points,” are sudden changes in the state of a system as it reaches a threshold, such as when water begins to boil as it turns to gas.

In the paper the scientists compare the biological impact of past incidences of global change with processes under way today and assess evidence for what the future holds. They note that studies of small-scale ecosystems show that once 50-90 percent of an area has been altered, an ecosystem tips irreversibly into a state far different from the original, in terms of the mix of plant and animal species and their interactions. This situation typically is accompanied by species extinctions and a loss of biodiversity, they say.

On a global scale, the result of such a major shift in the biosphere would be mixed, notes lead author Anthony Barnosky, professor of integrative biology at UC Berkeley. Some plant and animal species would disappear, leaving new mixes of remaining species. Agricultural crop production regions would shift. Climate change might lead to global political instability.

The paper acknowledges an urgent need for better predictive models that are based on a detailed understanding of how the biosphere reacted in the distant past to rapidly changing conditions, including climate and human population growth.

The paper’s 22 authors – biologists, ecologists, complex systems theoreticians, geologists, and paleontologists – argue that, although many warning signs are emerging, no one knows how close Earth is to a global tipping point, or if it is inevitable. They urge focused research to identify early warning signs of a global transition and an acceleration of efforts to address the root causes.

The paper emerged from a conference held at UC Berkeley in 2010 to discuss the idea of a global tipping point, and how to recognize and avoid it.

The paper appears in an issue of Nature devoted to the environment, in advance of the June 20-22 United Nations Rio+20 Earth Summit in Rio de Janeiro, Brazil.

Read the paper in Nature (June 6)

Read the UC Berkeley news release (June 6)