Planetary boundaries is a concept involving Earth system processes that contain environmental boundaries. It was proposed in 2009 by a group of Earth system and environmental scientists, led by Johan Rockström from the Stockholm Resilience Centre and Will Steffen from the Australian National University. The group wanted to define a “safe operating space for humanity” for the international community, including governments at all levels, international organizations, civil society, the scientific community and the private sector, as a precondition for sustainable development. The framework is based on scientific evidence that human actions since the Industrial Revolutionhave become the main driver of global environmental change.
According to the paradigm, “transgressing one or more planetary boundaries may be deleterious or even catastrophic due to the risk of crossing thresholds that will trigger non-linear, abrupt environmental change within continental-scale to planetary-scale systems.” The Earth system process boundaries mark the safe zone for the planet to the extent that they are not crossed. As of 2009, two boundaries have already been crossed, while others are in imminent danger of being crossed.
Please look at Joahan Rockström´s short clip on here; https://www.ted.com/talks/johan_rockstrom_10_years_to_transform_the_futu…
Fig 1. Planetary boundaries. Source: Steffen, W., Richardson, K., Rockström, J., Cornell, S. E., et al. (2015) Planetary boundaries: Guiding human development on a changing planet. Science 347 (6223). doi: 10.1126/science.1259855.