Extending marriage to same-sex couples is not only right for their personal fulfillment, as usually argued, but also important for the long-term survival of humankind and preservation of the global environment. PNS associate editor Andrew Reding is a senior fellow of the World Policy Institute in New York, and a city councilman in Florida.

It is fitting that Vermont, the state that pioneered environmental protection, may now become the first state to offer gays and lesbians the opportunity to marry. As a gay elected official and environmentalist, I see a natural link between pink and green.

In a world facing overpopulation, one of the more obvious environmental policy options is being overlooked -- making homosexuality more socially acceptable. With more than six billion humans taxing the carrying capacity of the biosphere, procreation is becoming more of a threat than a guarantee to human survival. That makes gay and lesbian relationships more environmentally-friendly than most heterosexual relationships because they don't contribute to population growth. And what better way to make homosexuality socially acceptable than to bless it with the institution of marriage?

Of course, sexual orientations are fairly inflexible. The sexual choices of persons who are "exclusively" gay or lesbian do not vary in response to changes in societal attitudes. But according to sex researchers, a large part of the population has intermediate tendencies. That means many individuals whose orientation is predominantly homosexual are capable of having heterosexual relationships even though they are less natural and

satisfying. Bisexuals can go either way with equal satisfaction.

In a homophobic environment, both groups tend to adjust to social norms by marrying the opposite sex and having children. Though less than ideal from the standpoint of personal fulfillment, this outcome is useful to society when its continued existence is threatened by insufficient numbers. Since most religious codes originated in such circumstances, they tend to frown on homosexuality and encourage the faithful to "be fruitful and multiply."

Yet we now face the opposite extreme -- a situation in which being too fruitful only compromises the future of all our children. The least coercive option is therefore to make it easier for persons who are bisexual or predominantly but not exclusively homosexual to enter into stable homosexual relationships.

Extending marriage to same-sex couples is not only right for their personal fulfillment, as usually argued, but also important for the long-term survival of humankind and preservation of the global environment. Under current restrictions, many gays and lesbians get married to members of the opposite sex for the wrong reason: to get society's blessing. If they had the option to get that same blessing -- and all the attendant benefits -- by marrying someone of the same sex, they would stop having children. Being able to marry would also enable them to more easily adopt the unwanted children of heterosexuals.

It may be objected that most of the world's population growth is occurring among the poorer nations of Latin America, Asia and Africa, precisely the regions that remain most homophobic. That is true, and a good reason to make the rights of homosexuals an integral part of the international human rights agenda. But it is equally true that the average resident of the United States and other developed countries places a far greater burden on the environment than his or her counterparts in poorer countries. According to the United Nations Human Development Report, the one-fifth of humankind that lives in high-income countries accounts for 86 percent of private consumption. It is us, not the Third World, that are primarily responsible for global warming, the thinning of the ozone layer and depletion of mineral resources.

It is also true that irresponsible behavior among gay men places an enormous burden on resources. Promiscuity and unprotected sex contribute to the spread of AIDS, a disease whose treatment remains shockingly costly. Yet that is all the more reason to encourage -- and reward -- monogamy and responsibility among homosexuals through marriage.

Contrary to what the Religious Right would have us believe, extending marriage to gay and lesbian couples would reinforce rather than erode respect for the institution. If love, faithfulness, caring and a stable family unit are not only personal but societal and environmental virtues, why restrict incentives to moral behavior to one portion of the population? Moreover, many divorces involve persons who married in order to meet society's expectations. Were these persons given the opportunity to follow their natural inclinations by marrying members of the same sex, it could only strengthen the institution of marriage, to the general benefit of society, morality, and the global environment.