If a resource (for instance, a limiting nutrient for plant growth) is abundant, it will typically recycle faster. This is a little strange, because recycling is not needed when a resource is non-limiting. A modelling study (J0rgensen and de Bernardi, 1997) indicates that free-energy storage increases when an abundant resource recycles faster. The result is shown in Figure 1.3. The ratio, R, of nitrogen (N) to phosphorus (P) cycling which gives the highest exergy is plotted in a logarithmic scale versus log(N/P). The plot in Figure 1.3 is also consistent with empirical results (Vollenweider, 1975). Of course, one cannot "inductively test'' anything with a model, but the indications and correspondence with the data do tend to support in a general way the exergy-storage hypothesis. The cycling ratio giving the highest ascendency is also correlated similarly to the N/P ratio (personal communication with R. Ulanowicz). In the light of the close relationship between exergy and ascendency, this result is not surprising (see above, J0rgensen, 1995a, Ulanowicz 1997).
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Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.