All measures to thwart the degradation and destruction of our ecosystem will be useless if we do not cut population growth. By 2050, if we continue to reproduce at the current rate, the planet will have between 8 billion and 10 billion people, according to a recent U.N. forecast. This is a 50 percent increase. And yet government-commissioned reviews, such as the Stern report in Britain, do not mention the word population. Books and documentaries that deal with the climate crisis, including Al Gore’s “An Inconvenient Truth,” fail to discuss the danger of population growth. This omission is odd, given that a doubling in population, even if we cut back on the use of fossil fuels, shut down all our coal-burning power plants and build seas of wind turbines, will plunge us into an age of extinction and desolation unseen since the end of the Mesozoic era, 65 million years ago, when the dinosaurs disappeared.

We are experiencing an accelerated obliteration of the planet’s life-forms — an estimated 8,760 species die off per year — because, simply put, there are too many people. Most of these extinctions are the direct result of the expanding need for energy, housing, food and other resources. The Yangtze River dolphin, Atlantic gray whale, West African black rhino, Merriam’s elk, California grizzly bear, silver trout, blue pike and dusky seaside sparrow are all victims of human overpopulation. Population growth, as E.O. Wilson says, is “the monster on the land.” Species are vanishing at a rate of a hundred to a thousand times faster than they did before the arrival of humans. If the current rate of extinction continues, Homo sapiens will be one of the few life-forms left on the planet, its members scrambling violently among themselves for water, food, fossil fuels and perhaps air until they too disappear. Humanity, Wilson says, is leaving the Cenozoic, the age of mammals, and entering the Eremozoic — the era of solitude. As long as the Earth is viewed as the personal property of the human race, a belief embraced by everyone from born-again Christians to Marxists to free-market economists, we are destined to soon inhabit a biological wasteland.

The populations in industrialized nations maintain their lifestyles because they have the military and economic power to consume a disproportionate share of the world’s resources. The United States alone gobbles up about 25 percent of the oil produced in the world each year. These nations view their stable or even zero growth birthrates as sufficient. It has been left to developing countries to cope with the emergent population crisis. India, Egypt, South Africa, Iran, Indonesia, Cuba and China, whose one-child policy has prevented the addition of 400 million people, have all tried to institute population control measures. But on most of the planet, population growth is exploding. The U.N. estimates that 200 million women worldwide do not have access to contraception. The population of the Persian Gulf states, along with the Israeli-occupied territories, will double in two decades, a rise that will ominously coincide with precipitous peak oil declines.

The overpopulated regions of the globe will ravage their local environments, cutting down rainforests and the few remaining wilderness areas, in a desperate bid to grow food. And the depletion and destruction of resources will eventually create an overpopulation problem in industrialized nations as well. The resources that industrialized nations consider their birthright will become harder and more expensive to obtain. Rising water levels on coastlines, which may submerge coastal nations such as Bangladesh, will disrupt agriculture and displace millions, who will attempt to flee to areas on the planet where life is still possible. The rising temperatures and droughts have already begun to destroy crop lands in Africa, Australia, Texas and California. The effects of this devastation will first be felt in places like Bangladesh, but will soon spread within our borders. Footprint data suggests that, based on current lifestyles, the sustainable population of the United Kingdom — the number of people the country could feed, fuel and support from its own biological capacity — is about 18 million. This means that in an age of extreme scarcity, some 43 million people in Great Britain would not be able to survive. Overpopulation will become a serious threat to the viability of many industrialized states the instant the cheap consumption of the world’s resources can no longer be maintained. This moment may be closer than we think.

A world where 8 billion to 10 billion people are competing for diminishing resources will not be peaceful. The industrialized nations will, as we have done in Iraq, turn to their militaries to ensure a steady supply of fossil fuels, minerals and other nonrenewable resources in the vain effort to sustain a lifestyle that will, in the end, be unsustainable. The collapse of industrial farming, which is made possible only with cheap oil, will lead to an increase in famine, disease and starvation. And the reaction of those on the bottom will be the low-tech tactic of terrorism and war. Perhaps the chaos and bloodshed will be so massive that overpopulation will be solved through violence, but this is hardly a comfort.James Lovelock, an independent British scientist who has spent most of his career locked out of the mainstream, warned several decades ago that disrupting the delicate balance of the Earth, which he refers to as a living body, would be a form of collective suicide. The atmosphere on Earth — 21 percent oxygen and 79 percent nitrogen — is not common among planets, he notes. These gases are generated, and maintained at an equable level for life’s processes, by living organisms themselves. Oxygen and nitrogen would disappear if the biosphere was destroyed. The result would be a greenhouse atmosphere similar to that of Venus, a planet that is consequently hundreds of degrees hotter than Earth. Lovelock argues that the atmosphere, oceans, rocks and soil are living entities. They constitute, he says, a self-regulating system. Lovelock, in support of this thesis, looked at the cycle in which algae in the oceans produce volatile sulfur compounds. These compounds act as seeds to form oceanic clouds. Without these dimethyl sulfide “seeds” the cooling oceanic clouds would be lost. This self-regulating system is remarkable because it maintains favorable conditions for human life. Its destruction would not mean the death of the planet. It would not mean the death of life-forms. But it would mean the death of Homo sapiens.

Lovelock advocates nuclear power and thermal solar power; the latter, he says, can be produced by huge mirrors mounted in deserts such as those in Arizona and the Sahara. He proposes reducing atmospheric carbon dioxide with large plastic cylinders thrust vertically into the ocean. These, he says, could bring nutrient-rich lower waters to the surface, producing an algal bloom that would increase the cloud cover. But he warns that these steps will be ineffective if we do not first control population growth. He believes the Earth is overpopulated by a factor of about seven. As the planet overheats — and he believes we can do nothing to halt this process — overpopulation will make all efforts to save the ecosystem futile.

Lovelock, in “The Revenge of Gaia,” said that if we do not radically and immediately cut greenhouse gas emissions, the human race might not die out but it would be reduced to “a few breeding pairs.” “The Vanishing Face of Gaia,” his latest book, which has for its subtitle “The Final Warning,” paints an even grimmer picture. Lovelock says a continued population boom will make the reduction of fossil fuel use impossible. If we do not reduce our emissions by 60 percent, something that can be achieved only by walking away from fossil fuels, the human race is doomed, he argues. Time is running out. This reduction will never take place, he says, unless we can dramatically reduce our birthrate.

All efforts to stanch the effects of climate change are not going to work if we do not practice vigorous population control. Overpopulation, in times of hardship, will create as much havoc in industrialized nations as in the impoverished slums around the globe where people struggle on less than two dollars a day. Population growth is often overlooked, or at best considered a secondary issue, by many environmentalists, but it is as fundamental to our survival as reducing the emissions that are melting the polar ice caps.