It’s not uncommon on the Web or in the popular press to see authors referring to United Nations population projections in arguing population growth isn’t a problem. Blogger Michael Kruse, writing from a particular Christian perspective, suggests the projections mean we will likely top out at a population which is “hardly a catastrophic number.” Writers such as neo-con, Ben Wattenberg, are similarly dismissive of any population problem and go on to fret over possible population declines in Western countries.
Projections, not predictions
Almost three months ago I posted an essay on the UN’s 2004 report, World Population to 2300 (large pdf). In it, I showed that the UN’s population projections are widely misinterpreted as predictions when in fact they are merely illustrative scenarios. That is one reason we cannot take much comfort in the UN’s projections; they don’t even pretend to be predictions we can count on. They are simply examinations of possible futures given assumptions based on observations of recent history. The authors concede they cannot begin to predict the social events which will influence future fertility rates. (Nevertheless, almost everyone, including writers of UN documents, talk about the projections as if they were predictions.)
But, as I hinted at the end of the previous essay on the UN report, there is another problem with statements relying on the UN projections to dismiss population as a problem. This will be familiar territory for regular readers and commenters here, but it’s an important piece of the rebuttal of the arguments of population deniers.
What if they were accurate predictions?
Though the projections aren’t predictions, what if we knew world population growth over the next half century or so would, in fact, match them perfectly? Could we feel some relief as a result?
The latest UN projections are in their 2006 revision. (pdf) It offers a medium variant showing world population reaching 9.2 billion by 2050. (This is up from 8.9 billion in the original 2004 report and 9.1 billion in its revision. [large pdf]) Assuming a current world population of 6.6 billion, that would mean an increase of just under 40% in the next 43 years. That might not be a problem were we now far below the Earth’s human carrying capacity or if our current global ecological footprint had us using far less than the resources of one earth. Sadly, that is not the case.
Estimates of carrying capacity vary, but reviews of the literature show many experts suggesting we are now near or even well beyond the number of humans the Earth can sustainably support at a decent standard of living. Gigi Richard provides a succinct review of the topic. Joel Cohen, author of How Many People Can the Earth Support?, has written the longest treatise on the subject. He concludes, “[T]he possibility must be considered seriously that the number of people on Earth has reached, or will reach within half a century, the maximum number the Earth can support in modes of life that we and our children and their children will chose to want.” (emphasis added, p. 367)
Turning to a newer measure, the developers of the global ecological footprint measure tell us humanity’s use of the Earth’s resources now exceeds by 23% what our planet can sustain. An effort at a more comprehensive footprint measure from the Redefining Progress group indicates the number is closer to 40%.
These indications that we are near or even considerably beyond the number of humans the Earth can support should be a clear indication that growth from 6.6 billion to 9.2 billion people is nothing to dismiss. Already, we are faced with one grave ecological problem after another. We see climate change, species extinctions rates as much as 1000 times normal (see the recent post on biodiversity at Trinifar), extreme overfishing of both the oceans and fresh water environments, deforestation, massive “dead zones” in the oceans, extensive loses of coral reefs, the global spread of chemical toxins (e.g., fire retardant in the bloodstreams of polar bears, who are themselves threatened), the likely peaking of world oil production, and projections of serious water shortages to come. Human population growth is linked to all of these problems.
With much damage already done, and some of it permanent, how will the Earth handle a population continuing to grow, whether by another 40% or some other amount?  What will be the human toll? Can we realistically expect to avoid conflict, death, and pervasive suffering as our resources dwindle and our ecosystem further erodes?
And that is only to think ahead to 2050. Any humane actions we can take to help reduce that growth and hasten population stabilization should mean a better future for our descendants.
In that light, it’s hard to imagine how some can brush off future population growth as a non-problem. When political and corporate agendas enter the picture, though, perhaps it’s not so hard to understand. Nevertheless it should be clear there is nothing in the UN report to warrant relaxing our concerns about population growth.
 Though the UN report is not meant to be read as a set of specific predictions, its data on past growth make clear we can expect substantial further growth in the coming decades. At some point population will stabilize. Unfortunately, many who study the topic fear that may result not from a a gentle landing through “demographic transition,” but from the tragic consequences of our overshoot the Earth’s carrying capacity.