Where is the limit? Planetary Boundaries: a safe operating space for humanity

A new approach to sustainable development is conveyed in the coming issue of the scientific journal Nature. A group of 28 internationally renowned scientists, including the academy members Carl Folke and Henning Rodhe, have made a first attempt to identify and quantify a set of nine planetary boundaries. The group propose that global biophysical boundaries, identified on the basis of the scientific understanding of the Earth System, can define a ‘safe planetary operating space’ that will allow humanity to continue to develop and thrive for generations to come.

The concept Planetary Boundaries is presented tomorrow at an international symposium at the Academy arranged by the Academy's Environment Committee and IGBP (International Geosphere-Biosphere Programme).

“Transgressing planetary boundaries may be devastating for humanity, but if we respect them we have a bright future for centuries ahead,” says lead author Professor Johan Rockström, Director of the Stockholm Resilience Centre at Stockholm University.

The group of scientists including also Johan Rockström, Hans Joachim Schellnhuber, Will Steffen, Katherine Richardson, Jonathan Foley and Nobel Laureate in chemistry 1995, 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 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.

 Nine boundaries were identified including;

• climate change
• stratospheric ozone
• land use change
• freshwater use
• biological diversity
• ocean acidification
• nitrogen and phosphorus inputs to the biosphere and oceans
• aerosol loading
• chemical pollution

The study suggests that three of these boundaries (climate change, biological diversity and nitrogen input to the biosphere) may already have been transgressed.The two latter ones have not yet gained as much media attention but are considered equally serious. In addition, it emphasizes that the boundaries are strongly connected in systems – 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 emphasize 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 affecting the Earth’s capacity to regulate itself. 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,” says co-author Professor Will Steffen, Director of the ANU Climate Change Institute at The Australian National University.

 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.

 “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 Professor Jonathan Foley, Director of the Institute on the Environment at the University of Minnesota.