Is it reasonable to expect, as my consumption model predicts, that total consumption will increase more rapidly as the population peaks and then declines over the next 40 years? Or will consumption (represented by the global ecological footprint) itself peak and decline rapidly, as an extrapolation of its per capita growth rate suggests? The answers to these questions hinge on another, more fundamental question: Is humanity inclined to use increased consumption to grow its population?
In my experience, most people do not prefer to decrease their personal consumption (though they may be forced to by external influences). If we do not decrease personal consumption, then the only rational way to increase population is to acquire more resources to support the new people, thus increasing overall consumption. Emergencies (such as people dying) tend to require more resources for such things as health care and repair of physical infrastructure; in other words, we generally want to restore things and people, as much as possible, to the way they were (and perhaps a bit better).
For consumption to peak rather than continue climbing, personal consumption must decrease. Such a decrease could be forced by a lack of resources, the disabling of enough people (or their technologies) to keep them from acquiring more resources, or an increase of altruism in the population. Certainly with petroleum becoming more expensive, availability of energy and materials is likely to drop dramatically by the middle of this century. Pollution is increasing to such a point that people could be disabled on a large scale (by, for example, disease and global warming induced disasters including hurricanes and droughts). There are people responding to global warming and dependence on unstable countries for energy by voluntarily reducing energy use, buying locally, and recycling.