The impact of human development on Earth systems is considerable. Originally developed and published in 2009, the planetary boundaries framework provides a means for succinctly visualising this human impact across nine key boundary segments deemed critical Earth-system processes.

The nine key boundary segments being:

1. Climate change
2. Change in biosphere integrity
3. Stratospheric ozone depletion
4. Ocean acidification
5. Biogeochemical flows
6. Land-system change
7. Freshwater use
8. Atmospheric aerosol loading
9. Introduction of novel entities

By scientifically analysing these boundaries a conceptual model is derived to articulate the relative human impact on each boundary. This analysis is aimed at providing a ‘safe operating space’ for human development that does not adversely impact upon Earth’s systems. Each boundary is assessed using credible, publicly disclosed control variables.

Transgression beyond a boundary is deemed to be operating outside the safe space which can result in significant, adverse ramifications for the planet and society. As at 2015, two such boundaries (and three sub-sets) were deemed to have transgressed this safe operating space: biosphere integrity and biogeochemical flows.

Another two boundaries were assessed as being in a zone of uncertainty: climate-change and land-system change. The zones of uncertainty serve as a precautionary buffer aimed at acknowledging not only the complexities in quantifying such boundaries but also to allow society an early warning sign and time to react prior to a threshold being transgressed.

Boundaries are also highly integrated and should not be viewed in isolation, the Earth system has itself co-evolved over four billion years. Further, in a hierarchical sense large changes in key boundaries such as biosphere integrity and climate change could result in the earth system being pushed from its current safe operating space, irrespective of other boundaries.

While succinct, the planetary boundary framework arises from scientific evidence that Earth is a single, infinitely complex, integrated system. The framework is not designed to be downscaled and applied in a regional context, e.g. nations or local communities. The unique heterogeneity of regional contexts is not readily captured by such global scale analysis.

The planetary boundary concept is iterative and designed to progress as scientific knowledge continues to evolve. This evolution will inform future assessment of what is a safe operating space for humanity.

1. The planetary boundary framework can be applied by finance sector actors to inform and assess environmental and social impacts, and risk assessments.
2. The nine planetary boundaries highlight key Earth systems and their functions that provide a safe operating space for human development.
3. Operating outside safe planetary boundary limits can result in severe environmental, economic and societal risks.
4. Application of the UN Sustainable Development Goals (SDGs) can only occur within a stable Earth system. The planetary boundaries framework provides a means for assessing the health of Earth systems at a global scale.
5. The framework recognises scientific evidence that Earth is a single, complex, integrated system; the boundaries operate as an interdependent set and not in isolation.
6. Since 2009 planetary boundaries definitions have been adapted to reflect enhanced knowledge and research while also recognising the impacts of novel entities (such as chemical pollution).
7. Planetary boundaries framework is not designed to be “downscaled” or “disaggregated” to regional contexts; it provides a global scale context.