Protected areas, biodiversity loss, jobs and human population growth

After convincingly arguing that current conservation efforts, including protected areas, cannot stop biodiversity losses, Camilo Mora and Peter F. Sale call for "stabilizing the size of the world’s human population" (Ongoing global biodiversity loss and the need to move beyond protected areas: a review of the technical and practical shortcomings of protected areas on land and sea, Marine Ecology Progress Series).

One could safely argue that biodiversity threats are ultimately determined by the size of the world’s human population and its consumption of natural resources. The explosive growth in the world’s human population in the last century has led to an increasing demand on the Earth’s ecological resources and a rapid decline in biodiversity.

They add that conserving biodiversity is not their only reason for "targeting human population growth directly."

[H]uman population growth may also lead to economic (e.g. high competition for and/or shortages of jobs; Becker et al. 1999) and societal (e.g. shortages of food and water, lack of universal primary education, increase in communicable disease, etc.; Campbell et al. 2007) problems [...]

I have checked the papers by Becker et al. and Campbell et al. In their op-ed, Campbell et al. 2007 do not relate the lack of universal primary education to population growth but to family size and do not relate communicable disease to population growth but mention that "preventing unintended pregnancies is the most cost-effective way of reducing mother-to-child transmission of AIDS." Campbell et al. do not mention water but do imply that hunger is related to population growth - ignoring the fact that hunger has been decreasing as population has increased.

Becker et al. 1999 do not mention job shortages or job competition. And, contrary to what Mora and Sale's citation implies, they are quite optimistic about productivity and human capital improvements in a growing population. This is Becker et al.'s conclusion:

Population may reduce productivity because of traditional diminishing returns from more intensive use of land and other natural resources. However, larger populations encourage greater specialization and increased investments in knowledge, mediated in part through bigger and more important cities. Therefore, the net relation between greater population and per capita incomes depends on whether the inducements to human capital and expansion of knowledge are stronger than diminishing returns to natural resources.

The  potential  importance of increasing returns to population in a world with rapidly growing population justifies a reconsideration of the relation between population and per capita incomes. 

Fortunately, this is what we are witnessing - a growing human population that is getting more productive and wealthy.

People create biodiversity

Here is an example:

[T]he Collaborative Cross, an ambitious project to create hundreds more mouse varieties representing a wider range of genetic diversity, is beginning to deliver its first animals. The new mouse strains have some very visible differences from one another — from variations in fur colour to tail length — and are already yielding clues to genes that help fend off fungal infection, which might not have been easily uncovered with standard lab strains.

Crowded Rwanda under siege?

There are few places in the world where the full pressure of population growth is felt as strongly as in tiny, landlocked Rwanda.

Thus starts an article in Nature by Josh Ruxin and Antoinette Habinshuti (Crowd control in Rwanda). While Rwanda currently "boasts economic growth, security and rising prosperity," Ruxin and Habinshuti believe that more population growth will lead to resource depletion, declining tourism due to poaching and encroachment in Rwanda's only major national park, and chronic poverty and malnutrition.

The authors advocate controlling population growth by promoting economic growth and girl education and offering "free" (by which they actually mean "paid by taxes") "contraceptives in every health centre and through every community health worker."

Until wealthier nations and large donors step up to fund family planning, poor nations themselves will have to take the lead. For those that choose this path — as Rwanda is doing — the rewards will be healthier, wealthier and smaller populations.

I do not object to voluntary donations to fund family planning, although I would rather give people the cash and let them decide how to spend it. But I do object to a couple of serious omissions by Ruxin and Habinshuti. They do not mention that people born in Rwanda could manage to prosper without those apparently dwindling resources by trading or migrating, as those born in crowded, tiny and landlocked Beijing, Frankfurt or Atlanta do.