Based on scientific consensus, these are the four root causes of the ways in which we compromise the ability of future generations to meet their needs. These are the basic ways in which we are un-sustainable:

	We dig stuff (like heavy metals and fossil fuels) out of the Earth’s crust and allow it to build up faster than nature can cope with it.
	We create man-made compounds and chemicals (like pesticides and fire retardants in carpets etc.) and allow them to build up faster than nature can cope with them.
	We contiuously damage natural systems and the free services they provide (including climate regulation and water filtration) by physical means (for example over-harvesting and paving wetlands).
	We live in and create societies in which many people cannot meet their basic needs (for example, finding affordable housing).

(To learn more about the four root causes of un-sustainability and the science behind them, please visit www.naturalstep.ca)