Hannon, B. “How might nature value man?” Ecological Economics 25 (1998): 265-279.

The aim of the article is to estimate quantitatively if the humanity is a burden for the Earth by means of calculation of so-called Gross Ecological Product (net outputs of the system multiplied by their ecological prices) with and without the presence of humans in the system of its production. If GEP rises with the presence of humans, then their existence is beneficial, if it falls, they are the burden.

The ecological prices of inputs and outputs are unified by transformation of their physical units into common energy units. According to the article, people can influence the GEP by the following ways:

• change of ecological prices (e.g. increase of vegetation cover decreases EP, reduction of vegetation life increases EP, increase of livestock increases EP (they consume vegetation cover));

• change of dissipation rate (e.g. extraction of minerals increases non-replaced dissipation rate);

• change of the amount and distribution of the metabolic costs (e.g. increase of area for vegetation and livestock increases MC, increase of sunlight consuming by one plant due to fertilizers increases MC), or

• combination of ways above.

The ways of influence on GEP reminded me about the I=PAT formula, where I is population impact, P – population size, A – per-capita affluence (or sometimes consumption), T – environmental damage caused by production of one consumption unit [1]. Reduction of dissipation rate reflects the reduction of technological impact of production, increase of population increases metabolic costs as far as every person depends on the sunlight for his/her growth (vitamin D3 is produced by the organism as a result of UV-exposure and is necessary for bone creation), change of consumption affects ecological prices. However I like the concept of GEP more than calculation of population impact, because the former provides the base for comparison (obviously, not only humans destroy ecosystems, the question is do we encourage the total destruction by being here), although it takes a huge amount of time to obtain the data for computation.

[1] G. C. Daily and P. R. Ehrlich, “Population, sustainability, and Earth's carrying capacity,” BioScience 42, no. 10 (1992), 762.

This post is a reprint of the original assignment for ENVM7202 Course, UQ, Semester 1 2009.