The current status of nine planet boundaries. Green zone is the safe operating space, yellow represents the increasing risk zone, and red is the high-risk zone. Processes for which global-level boundaries cannot yet be quantified are represented by gray wedges.
A recent article in Science magazine discussed an up-and-coming concept known to many scientists as “planetary boundaries.” Planetary boundaries help define the safe operating space within which societies can develop and thrive while protecting the environment.
At the heart of the concept, is quantifying our current scientific understanding of the functioning and resilience of earth systems and determining the tipping point at which human activity can alter major environmental processes. While some boundaries cannot yet be quantified, nine have been defined so far.
The United Nations is putting this concept to work by incorporating planetary boundaries in their Millennium Development Goals, which provide a framework and specific targets for sustainable global development.
Remember the hole in the ozone layer? This is an example where international cooperation has helped return a process back to within a safe boundary for humanity after being at high risk of global damage. Ozone concentration in the atmosphere has held steady for about 15 years and is expected to remain stable after phasing out the production and use of harmful, ozone depleting substances like chlorofluorocarbons (CFCs).
Currently, freshwater use is within a safe operating space. This planetary boundary is defined by the sustainable water consumption rate that would maintain healthy (fair to good) ecosystems in the freshwater bodies from which water is drawn.
However, phosphorus and nitrogen cycles are currently classified as high risk. Scientific observations point to a few major agricultural regions with abundance of phosphorus and nitrogen added and stored in the soil, thus considered as the main contributors to the transgression of this boundary.
High fertilizer application rates in these areas have caused the phosphorus and nitrogen cycles to become imbalanced. The map above speaks volumes about the significance of this imbalance. Green areas indicate regions that have a sustainable use of phosphorus; yellow areas are regions with an increased risk of the phosphorus cycle imbalance; and gray areas indicate regions where fertilizers are not applied. Red areas are regions where the phosphorus cycle is out of balance.
While phosphorus and nitrogen are important for agriculture, mismanagement and over-fertilization contribute to the degradation of waterbodies. This situation underscores the international significance of the Everglades Foundation’s George Barley Prize. This $10 million prize will incentivize a cost effective solution to the global problem of excessive phosphorus entering pristine, natural water bodies.
The concept of planetary boundaries will help guide human development on a changing planet. With it, comes the need to re-examine many environmental practices — particularly as they relate to high risk areas like phosphorus and nitrogen cycles — to ensure a sustainable future and safe operating space for generations and millennia to come.