Scientists identify nine planetary boundaries that humanity and others on the planet rely on. Three of them may have already been crossed.
A group of 30 leading Earth and Environmental scientists is proposing “nine planetary boundaries”, or safety zones, that must not be crossed in order to preserve the planetary and environmental balance that human civilizations (and much of the rest of the biosphere) require. Crossing these boundaries–and three of them may have already been crossed–could “generate unacceptable environmental change for humanity.”
Scientists Propose Nine Planetary Boundaries and “Safe Operating Zones”
The nine planetary boundaries, identified in a recent study paper published in Nature (commissioned by the Stockholm Resilience Centre), are as follows: 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 was an attempt to quantify the biophysical thresholds beyond which the “Earth System can no longer function in a stable state.” This “stable state” is defined by the scientists as that which, in the past, has “allowed human civilization to thrive.”
In regards to three of these boundaries (climate change, biological diversity, and nitrogen input to the biosphere), the authors believe that these may have already been crossed. Their research also emphasizes that these boundaries are all inextricably connected, and that transgressing any one of them makes it more difficult to stay within other boundaries.
As examples: we are already beginning to see increasing oceanic acidification (due to carbonic acid build up in marine systems) from (it is believed) excess atmospheric CO2, which harms many bio-productive coral species, and is both a form of chemical pollution and the prime driver of climate change. Also, the over-use of petrochemical fertilizers is increasing nitrogen loading of the biosphere, which has serious consequences for growth cycles, and further, nitrogen compounds form aerosols, which can cause ozone (O3) depletion through the generation of nitrous oxide (N2O).
View the short video of Planetary Boundaries co-author Will Steffen explaining two of these interconnected boundaries (climate change and land use change). Article continues below.
According to the SRC website, the nine boundaries paper is meant to be a framework within which nations can more readily identify areas of concern and for which to focus their resources and environmental efforts. Within these “safe operating zones”, societies will have some flexibility in terms of mitigating impacts and for “choosing pathways for our future development and well-being,” study co-author Professor Jonathan Foley of the University of Minnesota says.
“We are facing interconnected challenges.” — Johan Rockström (Director of the Stockholm Resilience Centre), and among the prominent list of speakers at the recent ‘State of the Planet 2010’ conference in New York
This generalized, conceptual framework is becoming increasingly popular outside the scientific community and is proving helpful to environmental and climate policy experts. The Planetary Boundaries paper was also presented at the recent State of the Planet 2010 Conference on March 25, at Columbia University (sponsored by The Earth Institute, Ericsson and The Economist)
View the video with Jeffrey D. Sachs of the Earth Institute at the State of the Planet 2010′ Conference (article continues below):
The authors of this study assert that human industrial activity over the past two centuries has created a new “global geophysical force” equivalent in many respects to any force of Nature. According to the authors, we are in the process of ending the Holocene era (a geologic era that commenced with the northern retreat of the glaciers and ushered in our current, more temperate climate) and are now initiating the Anthropocene era, in which human activity will have as much if not more impact on the biosphere as any natural or planetary force (such as the Earth’s orbital eccentricity).
The lead authors contributing to the published paper include:
Johan Rockström, Executive Director, Stockholm Resilience Centre, Kevin Noone, Professor, co-theme leader Global Environmental Change, Stockholm Resilience Centre, Hans Joachim Schellnhuber, Professor, Director of the Potsdam Institute for Climate Impact Research, Katherine Richardson, Professor, Earth System Science Center, University of Copenhagen, Will Steffen, Professor, co-theme leader for Global Environmental Change, Stockholm Resilience Centre and Director of the ANU Climate Change Institute, Australian National University, Jonathan Foley, Professor, Director of the Institute on the Environment, University of Minnesota.
Image Credit: NASA
Diagram & caption info credit: Sturle Hauge Simonsen, Stockholm Resilience Centre