A worker stands on a crane parked at a construction site at Keihin industrial zone in Kawasaki, south of Tokyo October 22, 2008.
A worker stands on a crane parked at a construction site at Keihin industrial zone in Kawasaki, south of Tokyo October 22, 2008.
Kim Kyung-Hoon / Reuters

Frances Beinecke

In 1970, U.S. President Richard Nixon signed the Clean Air Act into law, launching one of the most successful public health and environmental programs in history. In the first decade that followed, in Los Angeles, the amount of pollution from ozone -- the main component of smog -- exceeded government health standards on 200 days each year. By 2004, that number had dropped to 28 days. In the 1970s, also as a result of polluted air, nearly 90 percent of American children had lead in their blood at levels higher than what the Centers for Disease Control and Prevention deemed safe, and parents were alarmed by studies showing that lead interfered with cognitive development. Today, only two percent of children have such high levels of lead in their bodies. 

By controlling hazardous emissions, the Clean Air Act delivered these and many other health benefits. And it did so without curbing economic growth. The United States' GDP has risen by 207 percent since the law was passed over four decades ago. And because the law sparked innovation -- from catalytic converters, which convert toxic exhaust fumes from automobiles into less dangerous substances, to smokestack scrubbers -- pollution reductions have proved relatively inexpensive. According to the U.S. Environmental Protection Agency, for every dollar the United States has spent on cutting pollution through the Clean Air Act, it has gained more than $40 in benefits. 

Yet in his recent article ("Environmental Alarmism, Then and Now," July/August 2012), Bjørn Lomborg argues that the modern environmental movement has been distracted by unproductive goals and a desire to thwart economic growth. As evidence, he cites The Limits to Growth, a book published in 1972 by a group of scientists associated with the Club of Rome. The book cautioned that exponential increases in population, consumption, and pollution would exhaust the earth's finite natural resources and trigger the collapse of the world system. Lomborg rightly points out that the Club of Rome's worst forecasts never materialized, but he believes the book had a perverse effect on the way people think. "By recommending that the world limit development in order to head off a supposed future collapse," he writes, "The Limits to Growth led people to question the value of pursuing economic growth." 

Lomborg assumes that those who acknowledge that the planet has finite resources must necessarily oppose economic progress. This framing reveals the limitations of Lomborg's argument. The question the environmental movement asks is not, "How can we arrest growth?" The question is, "What kind of growth do we want?" For decades, heads of state, economists, captains of industry, and environmental leaders have opted for the type of growth that allows economic output to rise, makes the air cleaner, and preserves the planet's resources at the same time. 

The public call for environmental protection did not begin with the publication of a slender volume from the Club of Rome. It emerged from what people saw with their own eyes: raw sewage in the Great Lakes, smog so thick that it obscured the George Washington Bridge, oil despoiling Santa Barbara's pristine beaches, old-growth forests stripped bare in Oregon. It was Americans' desire to protect their families and their resources that ignited the modern environmental movement and inspired the passage of the Clean Air Act, the Clean Water Act, the Safe Drinking Water Act, and other landmark legislation.

Lomborg, however, claims that the Club of Rome's dire warnings distracted people from making real progress. "Spurred by analyses such as that presented in The Limits to Growth, much time and effort over the years has been diverted from useful activities to dubious or even pernicious ones." As an example, he says that instead of banning DDT, a known carcinogen, the United States should have focused on air pollution. He claims that because air pollution does not enjoy "celebrity backers," it has been "ignored." The lives saved by the Clean Air Act prove him wrong. For 40 years, the environmental movement has sought to make the air safer to breathe, the water cleaner to drink, and the wilderness better protected. Only those who forget the sight of yellow-brown haze or burning rivers would call this a distraction. 


Today, a new set of images reveals the hazards not of economic growth per se but of the unsustainable exploitation of natural resources. These are not predictions from a 40-year-old report but measurements of real developments. Right now, 90 percent of the world's large fish, such as tuna, swordfish, and marlin, have disappeared thanks to overfishing. This is alarming not just for the sake of the species themselves but also for industry and food supplies: the National Ocean Economics Program reports that between 1997 and 2007, California's commercial fishing revenues dropped by 43 percent because fish stocks were plummeting. Meanwhile, 90 percent of West Africa's rain forests have been destroyed, and between 2000 and 2005 alone, the world lost rain-forest acreage equal to the size of Germany. The amount of carbon dioxide in the air has increased by 23 percent over the last 50 years, driving climate change and intensifying such extreme weather events as the 2010 floods in Pakistan, which affected 20 million people, and the 2011 floods in Thailand, which caused more than $45 billion in damage.

Accounting for the world's natural capital is not alarmist; it is wise. Clean air, a stable climate, plentiful fish, lush forests, fresh water, and energy resources are the building blocks of prosperity. Identifying how to tap them without exhausting them will open the door to economic growth. 

Consider, for instance, the automobile industry. The United States can continue to waste oil, a limited and expensive resource, by burning it in inefficient engines that use outdated technologies. Or it can build cars that travel farther on less gasoline. The Obama administration has opted to encourage the latter by raising the fuel-efficiency standard to 54.6 miles per gallon by 2025. Within 20 years, better-performing cars will reduce U.S. oil use by more than the amount that the country imported from Iraq and Saudi Arabia in 2010. They will also save drivers more than $80 billion a year at the pump and, by 2025, halve the amount of carbon pollution emitted by vehicles in the United States. 

Even if the United States finally starts to clean up its automobile fleet, demand for cars is rising around the globe. Right now, there are about 800 million vehicles in use; by 2050, that number will rise to 2.5 billion. If the world is to meet this demand without sending oil prices through the roof, endangering public health with dirty tailpipes, and intensifying climate change, then it must start finding ways to make this growth greener.

The same holds for rising energy needs. Two-thirds of the buildings that are projected to exist in India in 2030, for instance, have not yet been built. David Goldstein, a scientist at the Natural Resources Defense Council, has argued that if India incorporates energy-saving features from the beginning of construction, it can reduce energy use by 50 percent at no additional cost. In other words, it makes more economic sense to start with efficient buildings than to retrofit them later. The production of efficient buildings and cleaner cars will generate billions of dollars for manufacturers and employ millions of people. That constitutes growth, but because it will use less energy and generate less pollution, it will be more sustainable growth. 

Lomborg fails to account for these gains because he persists in thinking that environmental leaders oppose economic growth. He is mistaken. At the recent Earth Summit in Rio de Janeiro, nobody called for an end to growth. Instead, the 50,000 heads of state, mayors, business executives, and citizens who gathered there affirmed that, despite Lomborg's claims to the contrary, infinite growth in the consumption of finite resources is simply not possible. Those of us who are concerned for the environment want economic growth. After all, prosperity often leads to greater environmental protection. We just want to do it right.

FRANCES BEINECKE is President of the Natural Resources Defense Council. 

Dennis Meadows

According to Bjørn Lomborg, The Limits to Growth, a short book written 40 years ago (and of which I am a co-author), is "mostly forgotten." Nevertheless, he believes that the book "helped set the terms of debate on crucial issues . . . with malign effects that remain embedded in public consciousness four decades later." 

Among those "malign effects" is the growing recognition that current economic policies can produce problems greater than their benefits. Lomborg rejects that perception, concluding, "It is past time to acknowledge that economic growth, for lack of a better word, is good, and that what the world needs is more of it, not less." 

The expansion of economic output over the past 250 years has produced enormous gains in human welfare. But conditions have changed. Humanity must now become more nuanced in its policies. We noted this in The Limits to Growth, writing, "Any human activity that does not require a large flow of irreplaceable resources or produce severe environmental degradation might continue to grow indefinitely."

Lomborg quotes only the first edition of our book, long out of print. Thus, readers cannot easily form their own conclusions. In Limits to Growth: The 30-Year Update, we used more recent data but still reached the original conclusions.

Lomborg's critique of our report boils down to the assertion that we predicted the exhaustion of resources before the year 2000. But we said repeatedly in The Limits to Growth that it is impossible to predict the future of social systems precisely. Instead, our goal was to understand long-term patterns of development for world population, capital, and other physical variables. We showed 12 different scenarios of the future, seven portraying collapse and five showing possibilities for a sustainable future. We declared unambiguously that the scenarios were "not exact predictions of the values of the variables at any particular year in the future. They are indications of the system's behavioral tendencies only." We were interested in patterns, not predictions. 

Unlike Lomborg, most readers noted this point. As the physicist Graham Turner wrote in a 2008 paper for Australia's Commonwealth Scientific and Industrial Research Organization (CSIRO) comparing The Limits to Growth's predictions with "thirty years of reality," the book "was not intended to be predictive or for making detailed forecasts, but to provide a means for better understanding the behaviour of the world economic system."

Lomborg claims that The Limits to Growth "worried about running out of oil (in 1990) and natural gas (in 1992)." But as Matthew Simmons, who was an energy adviser to U.S. President George W. Bush and a member of the National Petroleum Council, wrote in a 2000 white paper on energy, "Nowhere in the book was there any mention about running out of anything by 2000. Instead, the book's concern was entirely focused on what the world might look like 100 years later. There was not one sentence or even a single word written about an oil shortage, or limit to any specific resource, by the year 2000." 

Lomborg errs because his critique overwhelmingly draws on numbers he took from one data table in the first edition of The Limits to Growth. He presents those numbers as predictions generated by our computer model, even though our citations indicated that this table presented 1970 data compiled by the U.S. Bureau of Mines and other sources. We used the numbers solely to illustrate important differences between linear and exponential growth; they had no connection to our scenarios. What is more, Lomborg ignores the fact that we eliminated this table completely from the second and third editions of our book with no effect whatsoever on our results. 

Lomborg makes many other important mistakes. His discussion of his Figure 2, on commodity prices, ignores the rise in the commodity price index since the year 2000, which may herald a permanent shift in the trend. His Figure 3, on natural resource levels, confuses resource reserves with their crustal abundance. The first can be increased by raising prices; the second cannot. His Figure 4 compares the effects of short-lived air pollution with our scenario values for long-lived toxics, a category from which we explicitly excluded air pollution. 

Ignoring climate change, Lomborg suggests that conventional policies can solve society's problems. Many scientific studies contradict that view, most recently a report from IAP, a global network of 105 scientific academies. In June, IAP published a joint statement acknowledging that the global system is "on track to alternative futures with severe and potentially catastrophic implications for human well-being." 

The Limits to Growth said this in 1972, and Turner's CSIRO report has reconfirmed our concern. After analyzing empirical information on the development of global society, Turner concluded, "The analysis shows that 30 years of historical data compares favorably with key features of [The Limits to Growth's] business-as-usual scenario called the 'standard run' scenario, which results in collapse of the global system midway through the 21st Century."

To avert that result, we proposed deliberate measures for slowing physical expansion. Lomborg, by contrast, argues that human ingenuity alone will allow the world to overcome its environmental challenges. The problem is that he ignores the role ingenuity often plays in blocking constructive change. Irrespective of the problems it may cause humanity, every policy brings wealth, influence, and satisfaction to some. When that policy is challenged, its beneficiaries typically use their ingenuity to stymie useful alternatives. One may hope they will fail. But boosterism on the part of conventional economists only makes their task easier.

DENNIS MEADOWS is President of the Laboratory for Interactive Learning and Professor Emeritus of Systems Policy at the University of New Hampshire. As a faculty member at the Massachusetts Institute of Technology in 1970-72, he directed the Club of Rome project and co-authored The Limits to Growth.

Jørgen Randers

The Limits to Growth has been aggressively criticized since it first appeared in 1972 (I am one of its co-authors). But much of the criticism has been directed at straw men, so much so that during the 1970s and 1980s, a number of people who had never read the book gradually came to believe that it contained a number of statements that its authors had never actually made. One of them is the widely repeated allegation that the book predicted the end of oil before 1990, which it did not. Bjørn Lomborg's essay, which reproduces many of the arguments long used against those statements, is a classic example of the faulty criticism of the book.

The reason The Limits to Growth was attacked so fiercely on imaginary grounds is simple: as the chemist Ugo Bardi noted in his book The Limits to Growth Revisited, the study challenged central tenets of the worldview held and cherished by many Westerners. But despite Lomborg's claims, some of the major trends discussed in The Limits to Growth have in fact matched real developments since 1972. For example, the global population reached only six billion in 2000, as forecast in the "business-as-usual" scenario in The Limits to Growth, not seven billion, as most demographers had predicted in 1972.

The fundamental message of The Limits to Growth was that the world is small, and that if we want to live well and long on a small planet, we need to limit our ecological footprint. The sad fact is that despite the study's warnings, humans are already overwhelming the earth's carrying capacity. Today, humans emit twice as much greenhouse gases per year as the world's oceans and forests can absorb. This so-called overshoot cannot last. If human society does not reduce the size of its footprint, the ecological systems that underpin its well-being will collapse. The world must now either accept long-term chaos for the sake of short-term comforts or make short-term sacrifices for the sake of long-term comforts. Unfortunately, around the world and particularly in market democracies, decision-makers too often disregard long-term consequences. 

The Limits to Growth was supposed to help humanity make wiser policy choices. It warned that it was necessary to take action before distant problems became immediate crises and to spend on solutions while the sailing was still smooth. But the world's elites feared that such a change in the status quo would end both economic growth and their own privileged positions. And so the critics of The Limits to Growth instead tried to deny the problems it addressed and attacked the messenger. 

Rather than joining in the critical effort to reduce man-made greenhouse gas emissions, Lomborg revives a number of straw men and inaccurate claims about what The Limits to Growth said. The study did not predict that oil and other resources would run out before 2000. It did not assume that population and GDP would grow exponentially; their growth rates vary and were computed as an outcome of other drivers in the model. Nor did The Limits to Growth state that air pollution could or would kill humanity. Rather, it tried to estimate how strong the effect of persistent long-term pollutants would be on human health and food production. In other words, the study did not simply forecast the end of the world as we know it; it encouraged a wise human response to create a sustainable world.

Lomborg's assessment of the present state of affairs is even more troubling. He sees a world that is well on its way toward solving its environmental crisis and cites the progress that it has made in curbing air pollution. But by ignoring emissions of carbon dioxide, Lomborg overlooks the single greatest long-term threat to the environment. Emissions of carbon dioxide matter much more than those of shorter-lived pollutants, such as sulphur dioxide, since those are washed out of the atmosphere in weeks. Carbon dioxide has a half-life of 100 years, and emitting it causes lasting damage to the planet's climate.

In my recent book and Club of Rome report, 2052: A Global Forecast for the Next Forty Years, I argue that emissions of greenhouse gases will cause the world's temperature to rise to two degrees Celsius higher than in preindustrial times by 2052. In the following decades, the world will be three degrees Celsius warmer and probably warm enough to trigger a further and uncontrollable increase in the global average temperature caused by the gradual melting of the tundra. In short, this future is unpleasantly similar to the "persistent pollution scenario" from The Limits to Growth, with carbon dioxide as the persistent pollutant. 

The rise in greenhouse gas emissions will be the critical factor that shapes the future of life on earth. These emissions could easily be reduced if humanity decided to take action. But held back by myopic decision-making, humanity will not likely change its behavior. In modern, democratic market economies, investments mainly flow to what is profitable, not to what is needed. And regulators, who could in principle consider both economic growth and larger social needs, do not receive the necessary political mandates from shortsighted voters who want low taxes and cheap prices. Society can address the environment's problems only if it regains some control over the flow of investments.

Jørgen Randers is a Professor at BI Norwegian Business School. He is a co-author of The Limits to Growth and its two sequels.

John Harte and Mary Ellen Harte

In his essay, Bjørn Lomborg begins by criticizing the notion that the primary constraint on economic growth is the finiteness of resources, as if that remains the belief of the scientific community. Environmental scientists have long recognized, however, that the main limit to growth is not running out of resources but rather running out of space for the byproducts of that growth. Humans are filling the world's atmosphere with greenhouse gases, tainting its aquifer and surface water with deadly pollutants, eroding its soils, and allowing damaging toxics to build up in human bodies.

Obsessed with the numerical accuracy of projections made decades ago in The Limits to Growth, Lomborg ignores the importance of that study's qualitative insights, still valid today, concerning the interconnections between humanity and the natural world. The book illustrated the many ways in which increases in the human population and consumption levels undermine the sustainability of human society, including through pollution, the depletion of both renewable and nonrenewable resources, and industrial production. Lomborg also ignores some of the study's accurate quantitative insights: recent analyses by scientists show that The Limits to Growth was eerily correct in at least some of its most important projections. In a reexamination of the study, the ecologists Charles Hall and John Day showed that if a timeline were added to the book's predictions with 2000 at the halfway point, "then the model results are almost exactly on course some 35 years later in 2008." 

The Limits to Growth countered the blissful ignorance of many economists and business magnates who wanted to believe in the convenient pipe dream of unlimited growth, denying the finiteness of the natural environment. Many policymakers did understand the value of the study, however, and tried to inculcate its basic concepts into our civilization, but without success. The scientific community thus still has educational work to do, and finishing it is essential to securing a future for our civilization. 


Lomberg promotes numerous misconceptions in his essay. Bemoaning The Limits to Growth's results as neither "simple nor easy to understand," Lomborg fails to grasp what many reputable scientists and policymakers have long known: that predicting the details of complex phenomena is difficult. In that light, The Limits to Growth was just a first stab at analyzing the elaborate dynamics that cause continued economic growth to threaten the sustainability of human society.

Lomborg further displays scientific ignorance when he talks about pesticides. His estimate of 20 U.S. deaths annually from pesticides ignores both the ecological harm they cause and the human health problems, including cancer, hormone disruption, and neurological effects, associated with pesticide exposure. His argument that DDT is a cheap, effective solution to malaria overlooks the ability of mosquitoes, like other pests, to evolve resistance. Pesticides can be valuable tools when used as scalpels, but when they are used as bludgeons, the evolution of resistance often undoes their efficacy. This is why many epidemiologists fear that society is regressing from the happy era of working antibiotics. 

Lomborg also perpetuates the denial of the multiple ways in which civilization is underpinned by a healthy environment. Yes, we can continue to expand into previously untapped arable land, but only at the cost of undermining the giant planetary ecosystems that assure humanity will have clean air, clean water, and a sustainable and benign climate. Yes, we can forgo recycling and grow plantations for paper, but only at the expense of biodiversity. Indeed, as increasing population growth and overconsumption degrade the environment, none of the economic growth that Lomborg hopes for will be possible. Moreover, the capacity of society and its institutions to maintain, let alone improve, the quality of life -- a capacity that Lomborg takes for granted -- will be at risk.

Lomborg retells the story of how the biologist Paul Ehrlich, the physicist John Holdren, and one of us lost a bet in 1990 after the economist Julian Simon wagered that the prices of a number of commodities would drop over a ten-year period. But had the bet been extended a few more years, the scientists would have won, because the prices of those commodities had, on average, risen. Simon later challenged ecologists to a new set of bets on the future; Ehrlich and the climatologist Stephen Schneider accepted the challenge and picked 15 environmentally significant trends, such as the concentration of greenhouse gases in the atmosphere and the amount of biodiversity on the planet. To our surprise, once he recognized the trends, Simon saw the writing on the wall and promptly backed out of the bet; he would have lost more than $10,000. Indeed, the limitations on the human enterprise extend beyond minerals. World hunger is increasing, as is the cost of basic food staples. The temporary advances of the environmental movement, such as the creation of more ecological reserves to protect biodiversity, are proving less and less effective faced with the sheer weight of further population growth and increasing consumption.


Lomborg is correct that innovation is an important tool. Yet he seems to display a curious lack of confidence in human ingenuity when it comes to solving the environmental problems that science has identified to be of most concern to the future of humanity. He praises the very actions that cause climate disruption and pollution, such as offshore oil drilling, but has no such confidence that technological achievements can sharply reduce the world's dependence on fossil fuels. He revels in a food-production system that is awash in overused fertilizers, harmful pesticides, herbicides, and antibiotics, and is a major destroyer of the biodiversity on which it depends, but sees no hope for new inventions that could bring down the cost of organically produced food. Unfortunately, Lomborg seems to support ingenuity only in the cause of the trends he likes, rather than in the cause of technologies that could create a more sustainable future. 

In fact, the scientific community knows how to transition to renewable clean energy to create a safer, more politically stable world and prevent destructive climate change without decreasing the quality of life. We know how to stem the problem of overpopulation by supplying family-planning knowledge and contraceptives to the more than 100 million women who lack them in developing countries. Where the world most needs the ingenuity that Lomborg assures us exists is in replacing an economic system hooked on perpetual growth and overconsumption by the rich with one that is much more equitable and sustainable. 

Unlike Lomborg, most scientists understand the pernicious exponential effects of overpopulation on the environment. In 1993, 58 academies of science stated that "continuing population growth poses a great risk to humanity," and it now looks like the population could roughly double from its 1993 size by the end of this century. Other recent scientific statements have sounded an equally "alarmist" note, and with good reason. In March, for example, the participants at the "Planet Under Pressure" meeting, a gathering of climate-change scientists, declared that "the continued functioning of the Earth system as it has supported the well-being of human civilization in recent centuries is at risk. Without urgent action, we face threats to water, food, biodiversity and other critical resources: these threats risk intensifying economic, ecological and social crises, creating the potential for a humanitarian emergency on a global scale." To translate the warnings of the scientific community into action, the world desperately needs courageous political leadership to counter the powerful interest groups that continue to deny the unsustainability of humanity's current existence. 

The Limits to Growth helped educate a generation, and now more than ever, those concerned for humanity need to promote the solutions that can make society more sustainable. The denial of science is a perfectly harmless activity done in the privacy of one's own home, but when scientific misconceptions are laid out in the pages of the public media, as in Lomborg's essay, it is a threat to the world's well-being.

JOHN HARTE is Professor of Ecosystem Sciences at the University of California, Berkeley. MARY ELLEN HARTE is a biologist and columnist who writes on climate change and population.



The Limits to Growth predicted catastrophe: humanity would deplete natural resources and pollute itself to death. Its solution was less economic growth, more recycling, and organic farming. My essay documented how the book's predictions were wildly off, mainly because its authors ignored how innovation would help people overcome environmental challenges. 

Because the book's goal was so dramatic -- averting the end of the world -- its recommendation was for society to simultaneously do everything in its power to forestall that outcome. Today, much of the environmental movement continues to evince such alarmism and, consequently, is unable to prioritize. Developed countries focus as much on recycling, which achieves precious little at a high cost, as they do on attaining the much larger benefits from tackling air pollution, a massive, if declining, threat. Meanwhile, some environmentalists' demands are simply counterproductive. Avoiding pesticides, for example, means farming more land less efficiently, which leads to higher prices, more hunger, more disease (because of a lower intake of fruits and vegetables), and less biodiversity.

My essay argued that although the The Limits to Growth's analysis has been proved wrong, much of its doomsaying and policy advice still pervades the environmental debate 40 years later. These four critiques, instead of refuting my argument, in fact vindicate it.

First, only Dennis Meadows really tries to defend The Limits to Growth's predictions of collapse, and he does so with little conviction. Second, at least some of the responses accept in principle that society needs to prioritize among its different environmental goals and that economic growth will make achieving them easier -- in Frances Beinecke's words, "prosperity often leads to greater environmental protection." Third, all four of the critiques of my essay rely on the language of doom to motivate action, which, to the detriment of the environment, convinces society that it must pursue all its environmental goals at once, regardless of the costs and benefits. Finally, by focusing on the threats of economic growth to the environment, the authors generally neglect that growth has lifted billions of people out of grinding poverty and that others may remain poor because of the developed world's environmental concerns, real or imagined.


Defending The Limits to Growth, Meadows curiously complains that I address only the original book, which is "long out of print." He then posits that my case rests on one table from that book, on resource depletion, which he says I misrepresent. That is incorrect on several counts. 

First, it is patently false to claim, as Meadows does by way of a quotation from Matthew Simmons, that "nowhere in the book was there any mention about running out of anything by 2000." (Jørgen Randers makes a similar point.) The Limits to Growth quoted approvingly the first annual report by the U.S. government's Council on Environmental Quality, in 1970: "It would appear at present that the quantities of platinum, gold, zinc and lead are not sufficient to meet demands. At the present rate of expansion . . . silver, tin and uranium may be in short supply even at higher prices by the turn of the century." Meadows' own table publicized "the number of years known global reserves will last at current global consumption," showing that gold, lead, mercury, silver, tin, and zinc would not last to the year 2000. The instances go on.

According to the book's model, the main driver of the global system's so-called collapse would be the depletion of resources, and averting that outcome was the book's widely publicized rallying cry. So focusing on that aspect of the book can hardly be called a misrepresentation. What is more, claiming that this is my only critique ignores that I also showed how the book got pollution wrong and how its analysis of collapse simply did not follow.

Meadows and Randers both claim that in their model, pollution consisted of long-lived toxics, not air pollution. In fact, they were much more vague on this question in 1972. In the best case for their predictions of deadly pollution, they meant air pollution, which today accounts for about 62 percent of all environmental deaths, according to the World Bank and the World Health Organization. But if they indeed meant long-lived toxics, their prediction that "pollution rises very rapidly, causing an immediate increase in the death rate" has been clearly disproven by the declining global death rate and the massive reductions in persistent pollutants. 

John Harte and Mary Ellen Harte put forth a similarly weak defense of The Limits to Growth, as they do not challenge my data. They quote an article by the ecologists Charles Hall and John Day to say that The Limits to Growth's results were "almost exactly on course some 35 years later in 2008." This is simply wrong when it comes to resource levels, as the data in my original article shows, and indeed the cited article contains not a single reference for its claims about oil and copper resource reductions.

Harte and Harte further argue that the increase in the cost of resources during the last ten years is evidence of "the limitations on the human enterprise." Meadows claims that this uptick may "herald a permanent shift in the trend." Yet neither carries through the argument, because the empirical data from the past 150 years overwhelmingly undermine it. The reason is that a temporary increase in the scarcity of a resource causes its price to rise, which in turn encourages more exploration, substitution, and innovation across the entire chain of production, thereby negating any increase in scarcity. 

Harte and Harte demonstrate the unpleasant arrogance that accompanies the true faith, claiming that I "deny" knowledge, promote "scientific misconceptions," and display "scientific ignorance." They take particular issue with my assertion that DDT is a cheap solution to malaria, stating that I overlooked the issue of biological resistance. In fact, all malarial treatments face this problem, but DDT less so than the others. Whereas many malarial treatments, such as dieldrin, work only by killing insects, DDT also repels and irritates them. Dieldrin strongly selects for resistance, whereas DDT works in three ways and even repels 60 percent of DDT-resistant mosquitoes.


All four critiques contain grand dollops of doom. Beinecke invokes "alarming" environmental problems from overfishing to the destruction of the rain forests and global warming. These are real issues, but they, too, deserve practical thinking and careful prioritization. Fish and rain forests, like other resources subject to political control, tend to be overused. By contrast, when resources are controlled by individuals and private groups, their owners are forced to weigh long-term sustainability. 

Indeed, Beinecke's response reflects the most unfortunate legacy of The Limits to Growth: because of its persistent belief that the planet is in crisis, the environmental movement suggests tackling all environmental problems at once. This is impossible, of course, so society ends up focusing mainly on what catches the public's attention. Beinecke acknowledges that campaigns to enact environmental policy "emerged from what people saw with their own eyes: raw sewage in the Great Lakes, smog so thick that it obscured the George Washington Bridge, oil despoiling Santa Barbara's pristine beaches." Yet the smog killed more than 300,000 Americans annually, whereas the effects of the oil spills, although serious, were of a much lower order of magnitude. 

She claims that the U.S. Clean Air Act somehow contradicts my argument, when I in fact emphasized that society should have focused much more on cleaner air. Today, roughly 135,000 Americans still die from outdoor air pollution each year, and two million people, mostly in the developing world, die from indoor air pollution. Instead of focusing on the many negligible environmental problems that catch the public's attention, as the U.S. Environmental Protection Agency did when it focused so heavily on pesticides in the 1970s and 1980s, government should tackle the most important environmental problems, air quality chief among them. Beinecke misses this tradeoff entirely. 

Harte and Harte demonstrate a similar lack of proportion and priority. In response to my claim that a slightly larger portion of the world's arable land -- roughly five percent -- will need to be tapped in order to feed humanity, they offer an unsubstantiated fear that such an expansion would undermine "giant planetary ecosystems." Yet when they fret about pesticides, they seem impervious to the fact that eschewing them would require society to increase the acreage of land it farms by more than ten times that amount.


If The Limits to Growth erred in some of its quantitative projections, then perhaps, as Harte and Harte put it, its "qualitative insights [are] still valid today." Randers cites global warming as the new reason the book was right. Discussing his predictions for high carbon dioxide emissions, Randers writes, "This future is unpleasantly similar to the 'persistent pollution scenario' from The Limits to Growth."

But the comparison is unfounded and leads to poor judgment. In The Limits to Growth's original formulation, pollution led to civilizational decline and death. Although many environmentalists discuss global warming in similarly cataclysmic terms, the scenarios from the Intergovernmental Panel on Climate Change project instead a gradually worsening drag on development. Standard analyses show a reduction of zero to five percent of global GDP by 2100, in a world where the average person in the developing world will be 23 times as rich as he or she is today.

Moreover, although the responses to my essay invoke global warming as a new rallying cry for environmental activism, they fail to suggest specific actions to avert it. Harte and Harte claim that "the scientific community knows how to transition to renewable clean energy." Sure, developed countries have the technical know-how to adopt clean energy, but they have not done so because it would still be phenomenally expensive. Policies aimed at stopping climate change have failed for the last two decades because much of the environmental movement, clutching dearly to The Limits to Growth's alarmism and confident sense of purpose, has refused to weigh the costs and benefits and has demanded that countries immediately abandon all polluting sources of energy. 

Many economists, including the 27 climate economists involved in the 2009 Copenhagen Consensus on Climate conference, have pointed out smarter ways forward. The best means of tackling global warming would be to make substantial investments in green energy research and development, in order to find a way to produce clean energy at a lower cost than fossil fuels. As one of the leading advocates of this approach, I cannot comprehend how Harte and Harte could claim that I do not support clean-energy innovation. 

Unfortunately, the world will be hard-pressed to focus on smarter environmental policies until it has expunged the dreadful doom of The Limits to Growth. And unless the environmental movement can overcome its fear of economic growth, it will also too easily forget the plight of the billions of poor people who require, above all, more and faster growth.

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