Can Earth's and Society's Systems Meet the Needs of 10 Billion People?

The National Academies Press has just published a report of a workshop held in October of 2013 with the provocative title of Can Earth's and Society's Systems Meet the Needs of 10 Billion People?  [Note, btw, that you can download a free PDF copy of all NAP volumes.] Spoiler alert: the question is not answered! Rather, there are summaries of the workshop presentations that provide a lot of information that you, the reader/policy planner, can use in coming to your own decision. Most of the volume will be familiar to readers of Chapter 11 of my text, but of course there is a lot of useful detail and varying perspectives on the issues of population, environment, and climate change, among other things. One of the comments in the report struck me, though, as being a disservice to readers:

[T]he workshop was originally asked to address the concept of carrying capacity as a possible framework within which to consider the burgeoning human population of the Earth. Carrying capacity, a concept originated in animal ecology, refers to the maximum population size of a species that the environment can sustain indefinitely, to which it is able to provide an appropriate supply of food, water, habitat, and other natural resources. However, to some workshop participants, the concept of carrying capacity did not seem to be a useful framework for human populations and sustainability. In other words, although carrying capacity was expected to be a recurring theme of this workshop, it was not. Turner [Billie Turner of Arizona State University] noted that the more built up the environment is, the more difficult it becomes to apply the concept of carrying capacity, which assumes natural limitations (such as disease or starvation through drought) on animal species that are not technologically countered by that species. Because the human species manipulates and converts its habitat and can counter the natural limits on its population (such as by vaccinating for disease or providing emergency food to drought-struck areas), the conceptual basis of carrying capacity breaks down when considering people. Turner stated that carrying capacity should be only a heuristic device, and he cautioned against calculating specific values for the human-environment system. He stated that carrying capacity has been “largely abandoned” in the social and policy sciences.

I know and respect Billie Turner, but I think he's wrong about this. Carrying capacity continues to be a key concept for helping the public understand the relationship between population growth and the earth's resources. Indeed, Turner used the concept himself in his own workshop presentation.