PLANETARY BOUNDARIES: Can planetary boundaries help humanity manage its environmental impacts?Image: Courtesy of NASA
Is preserving the general environmental conditions that allowed civilization to flourish—a moderate climate, a rich array of species, rivers that reach the sea—necessary to ensure humanity endures? Or is minimizing alterations to the global environment introduced by human activity—rising levels of CO2 from fossil-fuel burning, widespread extinction, dams that impound water—more important to our success? Choosing the right approach is vital as the scale of human impact on the planet becomes so large that scientists are calling this new epoch in Earth's history the Anthropocene (when human activity alters global climate and ecosystems).
One bid for preservation initiated in 2009 by 29 scientists from around the world focused on the concept of planetary boundaries. They identified 10 environmental limits we might not want to transgress in the Anthropocene: aerosol pollution;biodiversity loss; chemical pollution; climate change; freshwater use; changes in land use (forests to fields, for example); nitrogen and phosphorus cycles; ocean acidity; and the ozone hole. That meme has now spread to the United Nations, and is driving ongoing global talks to address environmental problems, including the much-anticipated Rio+20 summit meeting that begins next week in Rio de Janeiro.