What is sd?
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Looking at sd Natural Step Ecology Economy Social


Wind turbine




Looking at sustainability: The Natural Step Framework


Natural systems are sustainable. They work in cycles.
Wastes are recycled to regenrate resources which can be used again.


Human activities often use up resources and produce wastes. This is not sustainable.


Burning excessive fossil fuels adds carbon dioxide to the atmosphere more quickly than it can be removed. It is not sustainable.

Solar, wind and wave power are being developed as sustainable energy sources.


The carbon cycle shows how nature recycles materials and does not produce wastes.

The Natural Step Framework looks at human activities by considering four systems.


A sustainable process meets all four system requirements.

  The Natural Step systems