by Alan Weisman
In his confirmation, Holdren testified that he did not believe that determining optimal population is a proper role of government.
The title they gave the superagency became fodder for Obama foes seeking proof that his administration belonged to a world socialist conspiracy. After someone broadcast quotes from Ecoscience on the Internet, Paul and Anne Ehrlich responded to the out-of-context selections of their views and those of their former colleague:
“We were not then, never have been, and are not now ‘advocates’ of the Draconian measures for population limitation described—but not recommended—in the book’s 60-plus small-type pages cataloging the full spectrum of population policies that, at the time, had either been tried in some country or analyzed by some commentator.”
During Gretchen Daily’s second summer at the Rocky Mountain Biological Lab, while she and Paul Ehrlich hiked back one afternoon after a day of tallying mating butterflies, they spotted a male red-naped sapsucker, a small western North American woodpecker, chiseling a rectangular patch of bark from a willow, then drinking the sugary sap that flowed down the exposed bare surface. Surrounding branches were pocked with other sap wells, indicating that sapsuckers regularly feasted there.
The next time Gretchen returned, she found an orange-crowned warbler and two kinds of hummingbirds imbibing at the sap well. Further observation—more than fifty hours’ worth, at her mentor’s encouragement—revealed forty species of birds, insects, squirrels, and chipmunks feeding off the sapsuckers’ labor.
Over the summer, intricate dynamics of alpine ecology revealed themselves to her. Sapsuckers needed willows to nourish themselves and their young, and a surrounding aspen grove for shelter. They also depended on a heartwood fungus that rots aspen trunks, enabling them to peck nesting cavities. Willow, aspen, and fungus had to occur together for sapsuckers to be there. To confirm, Daily and Ehrlich surveyed thirteen thousand quaking aspens at varying distances from willows: those that bore telltale sapsucker holes were the closest ones. They also examined all the willows: those far from aspens were unscathed by sapsuckers.
The sapsuckers, in turn, provided a significant source of food to a host of other animals. Since they drilled a new nest hole each year, their former homes were used by seven other bird species that couldn’t dig their own, including two kinds of swallows that appeared only where sapsuckers were present. An entire community of plants and animals all depended on a complex of keystone species: sapsucker, aspen, willow, and fungus. Take away any, and the others would decline or disappear.
This interdependence among plants, birds, insects, and mammals resulted in Daily’s first professional publication, coauthored with Ehrlich, just as she was starting her master’s degree. It was the beginning of her understanding of how losing a single species could touch off a cascade. After a year back in Germany to look at acid rain’s effect on Bavarian forests, she returned to Stanford to begin a doctorate, joining the Ehrlichs at their other perennial research site, the Las Cruces Biological Station in Coto Brus, Costa Rica.
It was the perfect place, Paul told her, for documenting what happens to wildlife when forests go. The massive bee study that kept Gretchen chained to a microscope for many months was led by Ehrlich and his own mentor, Charles D. Michener of the University of Kansas, the world’s greatest living bee authority.2 Besides confirming that forest bees pollinated farmers’ crops, something else surprising had turned up: Bee populations were actually thriving in the cleared spaces. So, Ehrlich had discovered, were butterflies and moths.
Possibly, they reasoned, this was because flying insects easily move between altered landscapes and where they actually live. Over the following years, they looked at less-mobile reptiles, amphibians, and nonflying mammals. They tracked and trapped frogs, toads, snakes, lizards, anteaters, pygmy squirrels, opossums, sloths, pacas, long-tailed weasels, puma, ocelots, river otters, and two species of monkeys. With all these, too, they found a higher capacity than expected of farmed countryside to sustain even threatened and endangered species.
The key in every case, they finally realized, was linked to trees. Wherever farmers left some standing, biodiversity hung on.
Not that a human-worked landscape was any substitute for native forest: Seven species—jaguar, tapir, white-lipped peccaries, howler and spider monkeys, giant anteaters, and an aquatic opossum—had disappeared. But a huge portion of the world’s land was now being used by people, and they were seeing that countryside that still contained some native vegetation cover could support a surprising percentage of native fauna. Such land could still provide services that humans needed: it could hold and filter water, replenish soil, and harbor creatures that pollinate crops and control pests.
Many scientists, they knew, would protest, contending that this conclusion could harm the worldwide conservation movement’s efforts to preserve remaining wilderness habitat for precious species. But the tiny percentage of the planet in nature reserves alone could only save a fraction of the world’s biodiversity. The concept of conservation had to be enlarged to include nonreserve lands as well. The challenge was convincing people who lived there that it was in their interest to coexist with whatever else still did, too.
In 1992, Gretchen Daily took a postdoctoral fellowship at Berkeley’s Energy and Resources Group with John Holdren. She needed to learn about energy: The modern agriculture that was transfiguring the land ran on the same fuels that stoked the planet’s engines of urbanity. The vast fertilized monocultures of the Green Revolution, where no trees were left standing—no anything but the cash crop—turned oil into food but failed to compost the carbon released in that chemical exchange.
At Berkeley, Holdren had her look at the converse: could agriculture grow fuel? Under the decade’s new watchword, sustainability, if living plants rather than their fossilized ancestors were the feedstock for the hydrocarbons that civilization now depended on, each new plant generation would inhale the CO2 released by the last one when burned. Theoretically, their carbon contributions to the atmosphere would zero out. But would they really? How much energy was needed to harvest and refine vegetation into biological fuel? How much would it compete with food production? Did it make sense to raise fuel crops on the same land as food crops? Or if biofuels were restricted to degraded lands, could anything grow there that would produce enough energy to make it worthwhile?
That same year, more than a hundred heads of state and thousands of scientists, activists, journalists, politicians, and emissaries of industry gathered in Rio de Janeiro for UNCED, the 1992 United Nations Conference on Environment and Development. The Earth Summit, as it became known, was portrayed as the watershed moment that might determine both the fate of the global ecosystem and the survival of the human race.
For two years before the meeting, ferocious parlaying ricocheted among member nations and thousands of entities whose interests were vested in the Earth Summit’s outcome. Besides environmental groups, these included women’s networks, human rights defenders, and religious leaders, from shamans to Vatican curia officials. Fifty of the biggest transnational companies pooled their clout to form the Business Council for Sustainable Development, predicated on hopes that economic growth could proceed unabated if ecological impact declined.
Everything on Earth was on the table—except for one. Despite a declaration by Earth Summit secretary-general Maurice Strong that “either we reduce the world’s population voluntarily, or nature will do this for us, but brutally,” by the time UNCED began, the topic was effectively taboo. Although groups named Population Action International, the Population Institute, and one Paul Ehrlich founded, Zero Population Growth, were among the multitudes in Rio, they were, fittingly, outnumbered.
Detractors, who called them “population controllers,” included developing countries that protested being blamed for the world’s environmental woes, when the real culprit, they insisted, was clearly the runaway consumption of rich nations. They rejected as racist neocolonialism the idea that li
miting a poor country’s greatest strength—numbers—could be touted as some sort of solution. Feminists added that women in poor countries were doubly abused: traditionally exploited, then forced to submit to involuntary sterilization or Norplant insertions they couldn’t remove by themselves.
The dilemma for population advocates was that they substantially agreed with the grievances of their accusers, and with their goals. Eliminating poverty, guaranteeing women’s reproductive rights, educating everyone, and social justice for all were aims they saw as crucial to achieving their own. The difference lay in strategy. While population groups believed that letting women control the number of children they bore was the swiftest way to reversing their plight, feminists had run out of patience with waiting for something else, such as wide implementation of family-planning programs, to happen before women had equal rights and opportunities. Anticonsumption groups insisted that the first order of business was to eliminate greed, not more greedy people. Arguments that the path to the success of any of these was to pursue them all simultaneously were lost amid the squabbling.
Their divisions proved useful to the Vatican. Invoking the sanctity of human life, it defended the contention that the world’s poor were victims, not the cause, of ecological degradation. As the Summit’s setting, Brazil, had the largest Catholic population in the world, the Church had considerable leverage in pre-session negotiations, and succeeded in deleting the terms family planning and contraception from UNCED draft agreements.
By the final version, the sole remaining reference to population was a single phrase, calling for “responsible planning of family size, in a spirit of liberty and dignity and in accordance with personal values, taking into account moral and cultural considerations.”
“The Holy See has not attempted to eliminate any wording relating to population, but only to improve it,” the Vatican announced when satisfied.
For the transnational companies that were major funders of the conference, more people meant both cheaper labor and expanding market bases, a point articulated eight years earlier at the 1984 World Population Conference in Mexico City. To the shock of the host country, Mexico, diligently trying to no longer be the world’s fastest-growing nation, the United States announced it would no longer support UN family-planning programs. Not only did they abet abortion, of which President Reagan’s administration did not approve, the U.S. representative explained, but the more people on the planet, the more consumers for the products of capitalism.
Since the United States was the UN’s biggest funder, and among the original patrons of its contraception programs, it was a policy flip that shook international family planning for years to come. Now, at the Rio Earth Summit, another unexpected reversal was occurring, as the United States stunned everyone by rejecting UNCED’s Convention on Biodiversity, under which every other nation agreed to identify and set aside reserves to protect genetic resources. This time, the U.S. complaint was that a provision for “fair and equitable sharing of benefits” from developing those resources constrained the intellectual property rights of biotechnology firms and pharmaceutical companies to products they might derive from tropical plants.
To American ecologists like Paul Ehrlich, such defiance could not be more perverse. For energy experts like John Holdren, things became even worse. As the eleven-day Earth Summit continued, U.S. president George H. W. Bush stayed in Washington, refusing to participate if another principal UNCED document, the Convention on Climate Change, established specific targets for emission reduction. Once again, every other signatory had agreed to limit CO2 emissions to 1990 levels by the year 2000. A prolonged, rabid debate ensued, led by countries that argued for a valid convention, even if it left the United States in glaring isolation. Ultimately, the rationale prevailed that any accord was meaningless without the world’s most powerful country and biggest polluter. The pact was diluted to meet U.S. demands, and the day before the conference ended, Bush arrived in Rio.
“The American way of life is not negotiable,” he said when he addressed the gathering.
The 1992 Earth Summit confirmed that only one species, H. sapiens, had a vote in deciding the fate of the Earth, as it was the only species at the table. In the long run, that vote will be meaningless: insects and microbes will likely have the last laugh, if they laugh at all.
The question, however, is when, exactly, is the long run? No one who has tried to predict that with any precision has been right thus far. Nevertheless, the failure of seers, or of skewed interpretations of Nostradamus or of Mayan calendars, should not lull anyone into complacency. Although outmuscled by politicians and lobbyists, scientists at the Earth Summit had plenty of reason to be concerned about our trajectory if things proceeded as usual.
A year later in Cambridge, England, at the First World Optimum Population Conference, Gretchen Daily and the Ehrlichs offered what they called a tentative, back-of-the-envelope calculation. They were not trying to pinpoint the end of human civilization, but rather to determine the opposite: how many humans could safely fit on the Earth without capsizing it?
Their presentation, twenty-five years after The Population Bomb was published, drew from a discussion of carrying capacity in Gretchen’s doctoral dissertation. Optimum population, they stated, did not mean the maximum number that could be crammed onto the planet like industrial chickens, but how many could live well without compromising the chance for future generations to do the same. At minimum, everyone should be guaranteed sustenance, shelter, education, health care, freedom from prejudice, and opportunities to earn a living.
That didn’t mean ending inequality. “While it is in nearly everyone’s selfish best interest to narrow the rich-poor gap, we are skeptical that the incentives driving social and economic inequalities can ever be fully overcome. We therefore think a global optimum should be determined with humanity’s characteristic selfishness and myopia in mind.”
Nor did they mean a pastoral, preindustrial existence. “[Optimum population] should be big enough to maintain human cultural diversity,” and in places dense enough to allow “a critical mass of intellectual, artistic, and technological creativity”—enough people to have “large, exciting cities and still maintain substantial tracts of wilderness.”
Yet it must be small enough to ensure that biodiversity is preserved. Their reasons were both practical—humans can’t live without the nourishment, air, materials, and water that nature provides—and moral:
“As the dominant species on the planet, we feel Homo sapiens should foster the continued existence of its only known living companions in the universe.”
To estimate optimum world population, they used a scenario developed by John Holdren. In that year, 1993, the planet’s 5½ billion people were consuming 13 terawatts—13 trillion watts—of human-generated energy. Nearly three-quarters of that were used by 1½ billion in industrialized countries, averaging 7½ kilowatts per person. If everyone used that much—in the developing world, the average was 1 kilowatt per person—and the world kept growing at the current pace, sometime in the twenty-first century there would be 14 billion humans and energy demand would be eight times higher.
Well before then, they feared, either oil or the ecosystem would collapse, or both. So Holdren had looked at what might be practical if everyone had equal access to energy. If demand averaged 3 kilowatts per capita (triple a poor person’s allotment; one-fourth what a typical American used, possibly achievable if energy efficiency were maximized), and if population growth rates eased enough to increase only to 10 billion,3 the total needed would still be 30 terawatts.4
Taking those figures, Daily and the Ehrlichs calculated backward. Since the 13 terawatts used in 1993 were already stripping the planet and scrambling atmospheric chemistry, they knew their total had to be lower. Assuming widespread adoption of clean technologies—some known, some yet to be developed—on the back of their envelope they hazarded a wild, wishful guess that it might be possible for the human race to use 9 terawatts every
year without trashing the environment.
To allow for unforeseen consequences, which invariably accompany technologies, they proposed a 50 percent margin of error. That left 6 terawatts. From there, it was just a matter of long division.
The total number of people, each using 3 kilowatts of energy apiece, that could live in a world using no more than 6 terawatts was 2 billion.
Two billion was the population of the Earth in 1930, when the Haber-Bosch process had just become commercially available worldwide. Nearly everyone on Earth was still living off plants growing on sunlight, not fossil fuel. At 2 billion, the world’s population could be fed with little or no artificial fertilizer, relieving pressures on the soil, on downstream waters, and on the atmosphere: agricultural nitrogen is a major source of nitrous oxide, both a pollutant and the most potent greenhouse gas after CO2 and methane.
In 1930, the world’s 2 billion used just over 2 terawatts of energy annually: slightly more than 1 kilowatt per person. It was a world without television, computers, fewer automobiles per family, minimal appliances, and no jet air travel. By today’s living standards, an allotment of 1 kilowatt per person per year would mean we’d all be considered underdeveloped, an option desired by few beyond survivalists and some remaining hunter-gatherers.
The Ehrlichs and Daily acknowledged that it was unlikely that even their calculation, which would give each of us triple that amount, would be very appealing. So they offered another alternative: in a world of 1½ billion people, everyone could have 4¾ kilowatts. That figure, nearly two-thirds the per capita energy usage of rich countries, was feasible without any major technological breakthroughs, simply through better insulation, better gas mileage, and increased use of inexpensive solar water heaters.
