Global Crew
Study Shows Earth Already
Past Three Tipping Points
A team of 28 scientists responsible for the groundbreaking paper, “Planetary Boundaries: A Safe Op- erating Space for Humanity,” pub- lished in Nature, have identified 10 biophysical systems that are crucial to humanity’s flourishing. They caution against “carbon blindness,” or focusing on atmospheric carbon dioxide concentrations above all else; rather, they point to 10 safe operating boundaries within which we must remain to maintain the basic environmental conditions in which we have evolved. “Human activities,” the sci-
entists warn, “have now reached a magnitude that may trigger irrevers- ible and, in some cases, abrupt en- vironmental change, by damaging the regulatory capacity of the sys- tems on Earth that keep the planet in the desired Holocene state” (that of the past 10,000 years). As of 2009, biodiversity loss
was already at more than four times the identified tipping point, closely followed by a damaged nitrogen cycle; climate change had just passed the crucial tipping point. Ocean acidification and stratospheric ozone depletion are currently at the tipping point. Land system change, the phosphorus cycle and global freshwater use are closing in on the critical point, with chemical pollution and atmo- spheric aerosol loading the other two categorical dangers.
Source: Grist.org
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April 2010
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