[jyl]

I'm not convinced that growing global population is a "critical" problem. Current projections are that global population will top out around 9 billion and then start dropping. This is based on fertility levels, which have dropped dramatically as populations become more urban and there is less economic benefit from having many children.

It is well known that fertility rates in Europe and Japan are already below the replacement level. China has reached that point too. Fertility rates have also been dropping rapidly in the Middle East and even in sub-Saharan Africa, contrary to the popular image.

What "may" emerge as a serious problem is that along with the peak-then-decline population trend, the population will also be aging. The percentage of young people will decline, the percentage of old people will increase. You already see this in Japan and Europe.

An aging population has many implications. Caring for retirees consumes a larger percentage of government and corporate budgets. Certain segments of the economy, like health care, add workers. Other segments, like the military, have a harder time finding workers. Older societies have historically tended to have slower economic growth and lower rates of technological innovation - that may prove true again. Immigration becomes an increasingly important source of economic growth, but also an increasing source of social friction.

[This is based on articles from various sources, including The Economist and Foreign Affairs. If anyone wants details, I can try to find and post them.]

P.S.: I edited the above to be clearer about my views. I think that a global population of 9 billion will be a "problem", in terms of environmental destruction, energy and resource consumption, and general quality of life. I am simply thinking that it is a survivable problem - the human race isn't likely to collapse into famine as Malthus warned. We'll manage to get by, although thousands of species of animals and millions of square miles of habitat won't be so lucky. At the same time I think the problem of aging populations is one that isn't as well appreciated.