Doing nothing, by contrast, will result in an unsustainable population of nine billion by 2050.

Humans are the only rational animals but have yet to prove it. Medical and other scientific advances have benefited by delivering lower infant mortality rates as well as longevity. Both are welcome, but humankind has not yet recalibrated its behavior to account for the fact that the world can only accommodate so many people, especially if billions get indoor plumbing and cars.

The fix is simple. It’s dramatic. And yet the world’s leaders don’t even have this on their agenda in Copenhagen. Instead there will be photo ops, posturing, optics, blah-blah-blah about climate science and climate fraud, announcements of giant wind farms, then cap-and-trade subsidies.

None will work unless a China one-child policy is imposed. Unfortunately, there are powerful opponents. Leaders of the world’s big fundamentalist religions preach in favor of procreation and fiercely oppose birth control. And most political leaders in emerging economies perpetuate a disastrous Catch-22: Many children (i.e. sons) stave off hardship in the absence of a social safety net or economic development, which, in turn, prevents protections or development.

China has proven that birth restriction is smart policy. Its middle class grows, all its citizens have housing, health care, education and food, and the one out of five human beings who live there are not overpopulating the planet.

For those who balk at the notion that governments should control family sizes, just wait until the growing human population turns twice as much pastureland into desert as is now the case, or when the Amazon is gone, the elephants disappear for good and wars erupt over water, scarce resources and spatial needs.

The point is that Copenhagen’s talking points are beside the point.

The only fix is if all countries drastically reduce their populations, clean up their messes and impose mandatory conservation measures

The Kid Issue: Shrinking populations bode poorly for world economies 
http://www.forbes.com/2009/09/07/japan-elections-birthrates-opinions-columnists-joel-kotkin_print.html

Japan's recent election, which overthrew the decades-long hegemony of the Liberal Democratic Party, was remarkable in its own right. But perhaps its most intriguing aspect was not the dawning of a new era but the emergence of the country's low birthrate as a major political concern.

Many Japanese recognize that their birth dearth contributes to the country's long-standing economic torpor. The kid issue was prominent in the campaign of newly elected Democratic Party Prime Minister Yukio Hatoyama, who promised to increase the current $100 a month subsidy per child to $280 and make public high school free. The Liberal Democrats also proposed their own pro-natalist program with a scheme for free child day care.

Japan's predicament seems obvious. Its fertility rate has dropped by a third since 1975. By 2015 a full quarter of the population will be over 65. Generally inhospitable to immigrants, Japan could see its population drop from a current 127 million to 95 million by 2050, with as much as 40% of the population over 65 years of age. By then, no matter how innovative the workforce, Dai Nippon will simply be too old to compete.

While Japan's demographic crisis is an extreme case, many countries throughout East Asia and Europe share a similar predicament. Even with its energy riches, Russia's low birth and high mortality rates suggest that its population will drop 30% by 2050 to less than one-third of that of the U.S. Even Prime Minister Vladimir Putin has spoken of "the serious threat of turning into a decaying nation."

Russia's de facto tsar has cause for concern. Throughout history low fertility and socioeconomic decline have been inextricably linked, creating a vicious cycle that affected once-vibrant civilizations such as as ancient Rome and 17th-century Venice.

Persistently low birthrates and sagging population growth inevitably undermine the growth capacity of an economy. Children provide a large consumer market and push their parents to work harder. By having children, parents also make a commitment to the future for themselves, their communities and their country.

In contrast, a largely childless society produces other attitudes. It tends to place greater emphasis on leisure activities over work. It also shifts political pressure away from future growth and toward paying pensions for the aging. An aging society is likely to resist risky innovation or infrastructure investments meant to serve future generations.

Of course, on a global level, lower birthrates should be seen as a positive. Population growth projections made around the time of The Population Bomb, Paul Ehrlich's widely acclaimed 1968 Malthusian tract, which predicted global mass starvation, have turned out to be well off the mark. Global population growth rates of 2% in the 1960s have dropped to less than half that rate, and projections of the number of earth's human residents in 2000 overshot the mark by over 200 million.

This pattern is likely to continue: growth rates will drop further largely due to an unanticipated drop in birthrates in developing countries such as Mexico and Iran. These declines are in part the result of increased urbanization, the education of women and higher property prices. The world's population, according to some estimates, could peak as early as 2050 and begin to fall by the end of the century.

Yet in some places, like Japan, declining birthrates may already be too much of a good thing. The same is true elsewhere in East Asia, particularly in China, where the one-child policy has set the stage for a rapidly aging population by mid-century. Fertility is particularly low in highly crowded Asian cities like Tokyo, Shanghai, Tainjin, Beijing and Seoul.

Over the past few decades a rapid workforce expansion fueled the rise of the so-called East Asian tigers, the great economic success story of the late 20th and early 21st centuries. But within the next four decades most of the developed countries in East Asia, as well as Europe, will become veritable old-age homes: A third or more of their populations will be over 65, compared with one in five in the U.S.

Not that the U.S. doesn't also have to cope with an aging population and lower population growth. But comparatively speaking it maintains a relatively youthful, dynamic demographic. Its fertility rate is about 50% higher than Russia's, Germany's or Japan's and well above those of China, Italy, Singapore, Korea and virtually every country in the former eastern Europe.

The reasons for this divergence with other advanced countries likely includes such things as continuing immigration, more land, larger houses, a strong aspirational culture and a higher degree of religious affiliation. Whatever the cause, a younger demography could lead to a relatively brighter future for America than is now commonly assumed.

Additionally, in the next decade the U.S. will benefit from a millennial baby boomlet, as the children of the original boomers start having offspring. This next surge in population may be delayed if tough economic times continue, but over time it will translate into a growing workforce, sustained consumer spending and will likely spur a rash of new creative inputs.

On the surface, these trends should help America to maintain a growing economy while its main competitors fade. By 2050 Europe's economy could be half that of the U.S. But this is not inevitable. As in Japan, some leaders in European countries understand they cannot sustain prosperity with a steadily declining workforce.

Many European countries are boosting benefits for families. In some, a pro-natalist policy is also being driven by concerns about the preservation of national cultures. In contrast to America, a country defined by immigration, most European countries--as well as Japan, China and Korea--have been far more resistant to outside influences.

The rise of immigration in recent decades has led to growing European nativist movements. Many Europeans, including liberal ones, are less than sanguine about the long-term consequences of Muslim birth rates now three times higher than those of indigenous Europeans. If current trends continue, according to the Brookings Institution, the Muslim population of Europe could double by 2015 while the non-Muslims shrink by 3.5%. Without a sustained boost in baby-making among native Europeans, much of the continent may soon confront the prospect of an essentially Islamic future.

But even so, attempts to foster a revival in European birthrates will face strong opposition from environmental activists who have amassed enormous influence. Some consider procreation of carbon-belching E.U. citizens as something close to anathema. In Great Britain, Jonathan Porritt, chair of the U.K.'s Sustainable Development Commission has advocates cutting the island's population in half as a way to reduce global greenhouse gases.

For their part, some America greens have expressed concern over our country's relative fecundity. The president's science adviser, John Holdren, a longtime protégé of Malthusian prophet Ehrlich, has in the past spoken about the need to limit families to two children. On the right, nativists also fear that too much of our new population will be of Asian or Hispanic descent.

These pressures could lead to curbs on immigration, which would slow population growth. Other steps being considered by administration planners, such as cramming Americans into smaller houses in urban centers, would clearly discourage family formation. A persistently weak economy would do the same.

Yet those favoring strong steps to curb population here first should think of the consequences. As the Japanese increasingly recognize, it's better to experience some population growth than to become a giant nursing home. A somewhat youthful, gradually growing population certainly may create considerable environmental and social challenges, but a scenario of persistent decline and rapid aging seems far worse.