Global biophysical boundaries can define a ‘safe planetary operating space’ that will allow humanity to continue to develop and thrive for generations to come, a group of 28 internationally renowned scientists proposes. Drawing upon current scientific understanding of the Earth System, the scientists make a first attempt to identify and quantify a set of nine planetary boundaries. This new approach to sustainable development that is to help humanity to deal with climate change and other global environmental threats in the 21st century is conveyed in the current issue of the scientific journal Nature.

Press release by the Stockholm Resilience Centre at Stockholm University, the Potsdam Institute for Climate Impact Research (PIK), the Australian National University, the University of Copenhagen, and the University of Minnesota

“Human pressure on the Earth System has reached a scale where abrupt global environmental change can no longer be excluded. To continue to live and operate safely, humanity has to stay away from critical ‘hard-wired’ thresholds in the Earth’s environment, and respect the nature of the planet's climatic, geophysical, atmospheric and ecological processes,” says lead author Johan Rockström, Director of the Stockholm Resilience Centre. "Transgressing planetary boundaries may be devastating for humanity, but if we respect them we have a bright future for centuries ahead.”

The scientists including Hans Joachim Schellnhuber, Director of the Potsdam Institute for Climate Impact Research, Will Steffen, Katherine Richardson, Jonathan Foley and Nobel Laureate Paul Crutzen, have attempted to quantify the safe biophysical boundaries outside which, they believe, the Earth System cannot function in a stable state, the state in which human civilizations have thrived.

The scientists identified nine Earth System processes and, for seven of these,  potential biophysical thresholds, which, if crossed, could generate unacceptable environmental change for humanity. The study suggests that three of these boundaries, namely climate change, biological diversity and nitrogen input to the biosphere, may already have been transgressed. Further boundaries are stratospheric ozone, land use change, freshwater use, ocean acidification, phosphorus inputs to the biosphere and oceans, and aerosol loading and chemical pollution. The authors emphasize that the boundaries are strongly connected – crossing one boundary may seriously threaten the ability to stay within safe levels of the others.

“What we now present is a novel framework through which our scientific understanding of the Earth System can potentially be used more directly in the societal decision making process,” says co-author Katherine Richardson, Professor at the Earth System Science Center at the University of Copenhagen.

The scientists state 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,” says co-author Will Steffen, Director of the Climate Change Institute at The Australian National University. “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.

Co-author Hans Joachim Schellnhuber points out that the climate system has clearly started to drift away from the familiar domain where historic experiences apply. The risk of highly nonlinear changes in our environmental conditions is sharply increasing outside that domain. “Observations of an incipient climate transition include the rapid retreat of summer sea ice in the Arctic Ocean, melting of almost all mountain glaciers around the world, and an increased rate of sea-level rise in the last ten to fifteen years,” Schellnhuber says.

The researchers stress that their approach does not offer a complete road map for sustainable development, but does provide an important element by identifying critical planetary boundaries. “Within these boundaries, humanity has the flexibility to choose pathways for our future development and well-being. In essence, we are drawing the first - albeit very preliminary - map of our planet’s safe operating zones. And beyond the edges of the map, we don’t want to go. Our future research will consider ways in which society can develop within these boundaries – safely, sanely and sustainably,” says co-author Jonathan Foley, Director of the Institute on the Environment at the University of Minnesota.

Feature article in Nature, September 24 issue

"Planetary Boundaries: A Safe Operating Space for Humanity", as well as individual commentaries and reader responses: http://www.nature.com/news/specials/planetaryboundaries/index.html

Full scientific article

"Planetary Boundaries: Exploring the safe operating space for humanity", and video interviews, graphics and further background material:

http://www.prnewswire.com/mnr/stockholmresilience/40125/

http://www.stockholmresilience.org/planetary-boundaries

Potsdam-Institut für Klimafolgenforschung e.V. (PIK) 2009