The Green Loops
Material living standards are dependent on the non-human world, through the provision of so-called ecosystem services. Firstly and most directly the basic functioning of ecosystems is necessary to provide us with clean air, water and fertile soils, a precondition for higher population levels. Secondly we are reliant on the exploitation of natural resources to provide us with food, energy and materials. This is the case for both basic subsistence living and for modern western lifestyles (although the quantities per person are radically different).
However there are limits to nature’s ability to provide ecosystem services. Higher levels of economic production deplete natural resources. Those that are finite (eg fossil fuels) will eventually run out completely (Loop B1). This creates feedback in the system which, if and when limits are reached, will reduce both economic production and population (Loop B2). These are known as balancing loops because, through feedback, an increase in a variable leads to its eventual decrease.
Evidence of the status of ecosystem services is provided by the 2005 Millennium Ecosystem Assessment and the Ecological Footprint analysis. These reports confirm the overexploitation of natural resources and the latter identifies that renewable resources are now being used at 1.5 times the rate that they are being replenished by natural processes.