Knowra Planetary boundaries Planetary boundaries Planetary boundaries are proposed limits on key Earth-system processes that define a safe operating space for humanity. Crossing a boundary increases the risk of large-scale, abrupt, or irreversible environmental change.
Earth system : The interacting physical, chemical, and biological components of Earth, including the atmosphere, oceans, land, and living organisms. The boundaries describe processes within this coupled system.
Control variable : A measurable quantity used to represent the state of a system or process. Each boundary is tracked through one or more selected indicators.
Sustainable development : Development that meets present needs while safeguarding the capacity of future generations to meet theirs. The framework links human development to the condition of Earth's life-support systems.
Doughnut economics : An economic framework that combines a social foundation with an ecological ceiling for human prosperity. It translates ecological limits into a model that also specifies social minimums.
Earth-system science : An interdisciplinary study of interactions among Earth's atmosphere, oceans, land, ice, and life. This field supplies the framework's integrated view of planetary change.
Biogeochemical cycle : The movement and transformation of chemical elements through living organisms, the atmosphere, water, and Earth's crust. Several boundaries concern disrupted global cycles of matter.
Planetary health : An interdisciplinary field studying how changes in Earth's natural systems affect human health and well-being. It connects environmental boundary pressures with consequences for people.
Limits to Growth : A 1972 systems study modeling how population, industrial growth, resources, and pollution interact over time. It shares concern about global ecological limits but uses a different modeling framework.
Environmental threshold : A point at which a gradual environmental change can trigger a disproportionately large shift in a system. Boundary values approximate thresholds beyond which risks rise.
Planetary boundary assessment : A scientific evaluation of boundary status using selected control variables and uncertainty estimates. Assessments determine how close processes are to, or beyond, their limits.
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