Planetary boundaries: Guiding human development on a changing planet

The relatively stable, 11,700-year-long Holocene epoch is the only state of the Earth System (ES) that we know for certain can support contemporary human societies. There is increasing evidence that human activities are affecting ES functioning to a degree that threatens the resilience of the ES—its ability to persist in a Holocene-like state in the face of increasing human pressures and shocks. The Planetary Boundary (PB) framework is based on critical processes that regulate ES functioning. By combining improved scientific understanding of ES functioning with the precautionary principle, the PB framework identifies levels of anthropogenic perturbations below which the risk of destabilization of the ES is likely to remain low—a “safe operating space” for global societal development. A zone of uncertainty for each PB highlights the area of increasing risk. The current level of anthropogenic impact on the ES, and thus the risk to the stability of the ES, is assessed by comparison with the proposed PB

Steffen et al Science 2015 http://www.sciencemag.org/content/347/6223/1259855.short