September 24^th
2009

An international group of 28 scientists has proposed nine planetary boundaries that the human race should not transgress if its civilizations are to continue into the future.Publishing in the journal Nature this week, the scientists have identified boundaries for climate change, stratospheric ozone, land-use change, freshwater use, biological diversity, ocean acidification, the nitrogen and phosphorus cycles, aerosol loading and chemical pollution.

The researchers emphasise that the rapid expansion of human activities since the industrial revolution has now generated a global geophysical force equivalent to some of the great forces of nature.“We are entering the Anthropocene, a new geological era in which our activities are threatening the Earth’s capacity to regulate itself,” explains report co-author Professor Will Steffen, Executive Director of the ANU Climate Change Institute.

“We are beginning to push the planet out of its current stable Holocene state, the warm period that began about 10,000 years ago and during which agriculture and complex societies, including our own, have developed and flourished. The expanding human enterprise could undermine the resilience of the Holocene state, which would otherwise continue for thousands of years into the future.”The researchers attempted to quantify the safe biophysical boundaries outside which the Earth’s environment can’t function in a stable state – the state in which human civilizations have thrived.

The team first identified the Earth System processes and potential biophysical thresholds, which, if crossed, could generate unacceptable environmental change for humanity. They then proposed the boundaries that should be respected in order to reduce the risk of crossing these thresholds.The study suggests that three of these boundaries (climate change, biological diversity and nitrogen input to the environment) may already have been transgressed. It also says that the boundaries are strongly connected, so crossing one boundary may seriously threaten the ability to stay within safe levels of the others.

The researchers stress that their approach does not offer a complete roadmap for sustainable development, but does provide an important element by identifying critical planetary boundaries. In addition to ANU, the scientific team includes Australian researchers from CSIRO and the ARC Centre of Excellence for Coral Reef Studies. The research was led by the Stockholm Resilience Centre at Stockholm University and included partners from around the world.

Download Nature article here: Planetary Boundaries

Download Planetary boundaries commentary here: Planetary Boundaries Climate Commentary

Download Planetary Boundaries paper here: Planetary Boundaries Paper

Listen to ANU Reporter Editor Simon Couper’s interview with Will Steffen here.

View a video presentation by Will Steffen courtesy of the Stockholm Resilience Centre here.

Photo: Prof Will Steffen near Aboriginal rock art in Arnhem Land - Australia