Tipping towards the unknown

Thursday, 24 September 2009 16:43

Researchers from SEI partner Stockholm Resilience Centre propose critical planetary boundaries, transgressing them could be catastrophic. But there is hope.

New approaches are needed to help humanity deal with climate change and other global environmental threats that lie ahead in the 21st century. A group of 28 internationally renowned scientists 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.

This new approach to sustainable development is conveyed in the coming issue of Nature where the scientists have made a first attempt to identify and quantify a set of nine planetary boundaries.

- The 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 Earth´s environment, and respect the nature of planet's climatic, geophysical, atmospheric and ecological processes, says lead author Johan Rockström, joint Director of SEI and the Stockholm Resilience Centre.

He warns that transgressing planetary boundaries may be devastating for humanity, but if we respect them we have a bright future for centuries ahead.

Read more about the planetary boundaries at Stockholm Resilience Centre website

Nine boundaries identified
The group of scientists including Hans Joachim Schellnhuber, 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 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 and 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. In addition, it emphasizes that the boundaries are strongly connected — crossing one boundary may seriously threaten the ability to stay within safe levels of the others.

Read more about the planetary boundaries at Stockholm Resilience Centre website