ONE has to look hard for ways in which to lump the relatively rich United States together with poorer Third World countries. But they are quite similar in one critical area impacting the environment: population growth.
This is one key conclusion to be drawn from the recent annual survey of the Population Reference Bureau, which reports that the US population growth rate (0.8 percent a year) is four times that of Europe and nearly three times that of Japan.
Such figures are in line with US Census Bureau projections that show this country's population climbing from today's level of 255 million to 383 million - and perhaps to as high as 500 million - in less than 60 years. Part of that increase has to do with immigrants entering this country at a rate unseen since the early part of this century - about 900,000 a year, or 1 out of every 100 people added to the world's population. Picture US public spaces a couple of generations hence with twice as many people.
Still, population growth rates in Western industrialized countries remain well below those in Asia, Latin America, and sub-Saharan Africa. There, where very large numbers of young people are entering their reproductive years, growth rates of 2 percent to 3 percent mean a doubled population in fewer than 30 years.
By coincidence, noted ecologist Garrett Hardin's new book, "Living Within Limits" (Oxford University Press), was published just two days after last week's world-population report.
Looking at present rates of consumption in a world of finite resources, he calls for tough measures: closing borders to immigrants from countries where governments are unwilling or unable to control population growth; limiting food aid in similar situations; subsidizing birth-control clinics.
Government coercion may be necessary, Mr. Hardin writes, "if nature is to be kept from controlling population by her own more brutal means." Above all, he asserts, overpopulation must be treated at the local level; unlike other major environmental issues, such as climate change, it can't be solved internationally.
Hardin is not as misanthropic or xenophobic as I make him sound in citing his more controversial conclusions. He does favor international aid to help countries help themselves control population. Such aid is likely to increase under the Clinton administration and from other advanced countries as the world approaches the United Nations Conference on Population and Development in Cairo next year.
Even stabilizing world population at double the current level of 5.4 billion people "would require a massive and immediate international effort to implement family planning and development programs known to reduce birthrates rapidly," writes Sharon Camp, senior vice president of Population Action International in the spring issue of Foreign Policy magazine.
Dr. Camp notes that the number of couples of child-bearing age is increasing by 18 million a year, but that meanwhile the "unmet need for fertility control affects somewhere between 90 [million] and 160 million couples."
There is evidence that government action to control population is beginning to pay off in some places. Each year recently, Population Action International has been publicizing five countries having the most success in this regard.
The "population picks" for 1992 were Indonesia, Bangladesh, Iran, Peru, and Zimbabwe. Each was cited for making "impressive, recent progress in expanding access to family planning services," which has resulted in smaller average family size. Countries so recognized in 1991 were India, Thailand, Colombia, Morocco, and Kenya.
Yet much remains to be done. The typical Bangladeshi woman now has four children compared with seven a decade ago - but with more than 100 million people packed into an area the size of Wisconsin, Bangladesh remains the most densely populated country in the world. Iran's "renewed political commitment to rebuild family planning services ... may be one of the country's best-kept secrets," the report states, but the typical Iranian woman still has six children.
And because of birth rates and immigration, it's possible that this generation of American children will live in a country twice as crowded by the time they are grandparents.