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, according to a new study published in the current issue of Nature.
A group of 28 internationally renowned scientists have made a first attempt to identify and quantify a set of nine
planetary boundaries, including climate change, freshwater use,
biological diversity, and aerosol loading.
They say that new approaches are needed to help humanity deal with climate change and other global environmental threats that lie ahead in the 21st century.
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.
As a result, three of the identified boundaries have already been crossed: climate change, biodiversity loss and nitrogen cycle.
"We are entering the Anthropocene, a new geological era in which our activities are threatening the earth's capacity to regulate itself," said co-author Will Steffen, professor at the Australian National University (ANU) and 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."
Planetary boundaries is a way of thinking that will not replace
politics, economics, or ethics, explained environmental historian
Sverker Sörlin of the Stockholm Resilience Centre and the Royal
Institute of Technology, Stockholm. "But it will help tell all of us
where the dangerous limits are and therefore when it is ethically
unfair to allow more emissions of dangerous substances, further
reduction of biodiversity, or to continue the erosion of the resource
base. It provides the ultimate guardrails that can help societies to
take action politically, economically. Planetary boundaries should be
seen both as signals of the need for caution and as an encouragement to
innovation and new thinking of how to operate safely within these
boundaries while at same time securing human well being for all."
Robert Costanza, director of the Gund Institute at the University of Vermont and one of the IHOPE project leaders at NCEAS, said: "The Nature article provides evidence of the necessities to establish a thorough, long-term historical understanding of the exchange between human societies and the earth system, in order to set standards for safe navigation within planetary boundaries and avoid crossing dangerous thresholds."
Lead author Johan Rockström, director of the Stockholm Resilience Centre at Stockholm University, said: "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 the planet's climatic, geophysical, atmospheric and ecological processes. Transgressing planetary boundaries may be devastating for humanity, but if we respect them we have a bright future for centuries ahead."
The research was performed by a working group at UC Santa Barbara's
National Center for Ecological Analysis and Synthesis (NCEAS), in
cooperation with the Stockholm Resilience Centre at Stockholm
University.
The Nature feature can be read online at the link below.
