The Global System
This picture is known a causal loop diagram. It seeks to depict cause and effect and feedback in a system over time. Although all the loops act simultaneously it is helpful to consider them one at a time. The polarity of the arrows indicates the effect of one variable on another. As examples, in the above:
- Higher living standards lead to higher levels of overall wellbeing (all other things being constant) so the causation is positive.
- Higher levels of economic production lead to lower levels of natural resources (all other things being constant) so the causation is negative.
For clarity I have only labelled the negative causations. All unlabelled arrows indicate positive causation.
This highly simplified depiction provides the basis for understanding cause and effect in the global socio-ecological system. However there are many different trajectories (behaviour over time) for this system. You cannot tell by looking at this picture what the future state of the system may be (bearing in mind that no model can accurately predict the future). Clearly growth due to the reinforcing loops R1 and R2 have dominated the balancing loops as real world data on population, economic growth and living standards show.
The sustainability question is therefore what will happen in the future as the world population grows towards 9 billion, poorer nations become richer, the effects of pollution (particularly carbon) grow, and resources become depleted. To investigate plausible scenarios for the future requires a full global systems model.