Feedback mechanisms have thresholds -- tipping points beyond which regulatory mechanisms fail. For example, perspiration is a feedback mechanism that keeps temperature from rising in some mammals. But the system has limits beyond which it will not protect the body from excessive heating.
Similarly, the Earth as a whole has a lot of mechanisms that tend to limit the damage we do to it. This study published in Nature and reported on MSNBC is the first comprehensive analysis of these thresholds on a global scale. The results are not encouraging. With respect to climate, nutrient loading, species extinction, and too many other systems, human activity is pushing the Earth past its thresholds.
Author Jonathon Foley says that the most important lesson is "that 'wait and see' is a bad environmental policy." Because this news is unpleasant, I anticipate most responses to range from apathy to a "shoot the messenger" effort to discredit the work. We can hope, however, that people will start to think about the fundamental problem of unlimited growth on finite planet.