In 2009, a group of scientists led by Johan Rockström from the Stockholm Resilience Centre proposed a framework of “planetary boundaries” designed to define a “safe operating space for humanity”. This framework is based on scientific research that indicates that since the Industrial Revolution, human actions have gradually become the main driver of global environmental change.

The scientists assert that once human activity has passed certain thresholds or tipping points, defined as “planetary boundaries”, there is a risk of “irreversible and abrupt environmental change”.

A total of nine boundaries are identified: climate change, rate of biodiversity loss, biogeochemical flows (both nitrogen and phosphorus), stratospheric ozone depletion, ocean acidification, global freshwater use, change in land use, atmospheric aerosol loading and chemical pollution.

The scientists estimate that human activity appears to have already transgressed the boundaries associated with climate change, rate of biodiversity loss and changes to the global nitrogen cycle.
Further findings suggest that humanity may soon be approaching the boundaries for interference with the global phosphorous cycle, global freshwater use, ocean acidification and global change in land use.

The scientists suggest that the boundaries are strongly interlinked, so that crossing one may shift others and even cause them to be overstepped.

While the scientists themselves stressed that their assessments were only initial estimates, their work represents an important shift towards more systematic monitoring of humanity’s impact on its environment.
Source: The Stockholm Resilience Centre. More information is available at www.stockholmresilience.org.