Biophysical reality is the fundamental reality of our existence that is dependent on the physical laws of nature, such as the conservation of energy, and the reality that underpins the limited availability of energy, materials and resources to support human civilization. It is the realization that, despite our own beliefs, we are subject to the biophysical limits of the planet, and must understand and interact with them in order to ensure our long-term well-being. Ultimately, the only truly "sustainable" lifestyle is one based on managing resources optimally, given biophysical reality.

See also: climate model, ecological footprint, renewable energy, fossil energy, nuclear power