Global Crew

Study Shows Earth Already Past Three Tipping Points




A team of 28 scientists responsible for the groundbreaking paper, “Planetary Boundaries: A Safe Operating Space for Humanity,” published 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 scientists warn, “have now reached a magnitude that may trigger irreversible and, in some cases, abrupt environmental change, by damaging the regulatory capacity of the systems on Earth that keep the planet in the desired Holocene state” (that of the past 10,000 years).

Co-author Hans Joachim Schellnhuber points out that the climate system has clearly started to drift away from the familiar domain where historic experiences apply. The risk of highly nonlinear changes in our environmental conditions is sharply increasing outside that domain. “Observations of an incipient climate transition include the rapid retreat of summer sea ice in the Arctic Ocean, melting of almost all mountain glaciers around the world, and an increased rate of sea-level rise in the last ten to fifteen years,” Schellnhuber says.
 

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 atmospheric aerosol loading the other two categorical dangers.

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