A comparison of the properties of the natural environment versus the built environment is simple. For example, a tree requires only the natural energy of its immediate environment versus the immense embodied energy required for a house. Not only that, the tree provides oxygen, creates its own micro ecology and cools its immediate vicinity with shade and the absorption of energy in the infrared wavelength. Sort of a natural solar collector and carbon sink. In this way, life has created its own method of sustaining itself using sunlight and water. Then you look at what human civilization has produced, which are structures which reverse the natural processes and use tremendous amounts of energy during their lifetime plus the embodied energies of its structure and the oil, gas and water used to make and transport its parts, as well as the energy to build it and snuff out the functioning ecosystem that used to be in its place. So these are little hotspots where the energy transfer works in reverse to the natural flow. When one aggregates many of these hotspots over an area, it creates a very destructive black hole. These black holes can be mapped.
So clearly if these black holes are not significantly balanced out with a healthy biosphere, the entire system collapses. This is in addition to the heat of carbon that's emitted by their existence as well as the transportation and shipping networks that support human habitation systems. Climate change is but one facet of the black hole problem. So there is a limit to the built environment that the planet can handle without the destruction of the ecological systems that support life on the planet.
Urban expansion - the black holes - will threaten biodiversity and impact the ability of the natural environment to function. There is a limit to the amount of human habitation that the planet can support, and we've passed that limit. We're now encroaching on the last remnants of the natural environment that provides what little balance is left in the ecosystem.
An explanation of the fiscal drivers that create these massive urban developments is described in an article that outlines how cities grow, particularly in California, but also across the globe. In effect, the financial models force more and more building for the cities to survive on the revenue this produces. This fiscal model is what drives the black holes that are shredding the ecosphere. The model is shifting to the premise that the form of cities must change because sprawl is too expensive, a retreat from the event horizon. Unfortunately for the fiscal model, the proposed solution of creating more dense development feeds right into the expansion of these black holes; it becomes a self-perpetuating cancer. This is not a solution for the long term. And these dense centers are poised to explode even further.
Unless human civilization comes to grips with its destructive proclivities, and reduces its footprint on the planet, there's not much hope for continued sustainable life on the planet. The ecological footprint must be reduced very rapidly by all the countries on the globe, and readjust our priorities as a civilization that allows us to adapt to the limitations of planetary resources and ecology. Therefore, the adoption of a new fiscal measure of productivity is imperative in our global systems.