According to an international team of researchers, four of nine planetary boundaries have now been crossed as a result of human activity. These are:

• climate change
• loss of biosphere integrity
• land-system change
• altered biogeochemical cycles (phosphorus and nitrogen).

Publishing in the in the journal Science, the team of 18 researchers explain that climate change and biosphere integrity are "core boundaries". The other five boundaries are:

• Stratospheric ozone depletion
• Ocean acidification
• Freshwater use
• Atmospheric aerosol loading (microscopic particles in the atmosphere that affect climate and living organisms)
• Introduction of novel entities (e.g. organic pollutants, radioactive materials, nanomaterials, and micro-plastics)

Significantly altering either of the two "core boundaries" would "drive the Earth System into a new state".  Lead author Professor Will Steffen, researcher at the Centre and the Australian National University, Canberra said:

Transgressing a boundary increases the risk that human activities could inadvertently drive the Earth System into a much less hospitable state, damaging efforts to reduce poverty and leading to a deterioration of human wellbeing in many parts of the world, including wealthy countries.

 Graph: Stockholm Resilience Centre 

The authors also emphasize that the findings present “a great opportunity to turn things around.”

The study will be presented at the World Economic Forum in Davos 21-24 January.

 See the Stockhold Resilience Centre press release on the study