Global Warming: Apocalypse Now?
In 1906 the Swedish chemist Svante Arrhenius published a popular book speculating on the origins of the earth and of life upon it. (An English translation, Worlds in the Making, appeared in 1908.) In a nutshell, Arrhenius proposed that the solar system was born of a collision between cool stars, with the sun and the planets forming from the resulting nebular debris. The planets, he thought, were then seeded by living spores that had been propelled through the cosmos by electromagnetic radiation.
Unfortunately for Arrhenius, few of these ideas ever achieved wide currency, and most of them were considered far-fetched even at the turn of the last century. One, however, has lately experienced something of a revival: the notion that the earth's climate is maintained within bounds that are favorable to life by the concentration of carbon dioxide (CO2) in the atmosphere. As early as 1896, Arrhenius had proposed that surface temperatures rise in proportion to atmospheric CO2, which absorbs radiated heat that would otherwise escape into space. Noting that CO2 can be generated by the burning of coal, Arrhenius predicted that the growth of industry might eventually result in a warmer planet (in modern terms, this would be called “anthropogenic forcing”)—a salutary outcome from a Scandinavian point of view, since a more temperate climate would likely be a boon to agriculture in the North.
This “greenhouse effect” is the cornerstone of the contemporary notion of global warming.
1 A hundred years after Arrhenius wrote, the concentration of CO2 in the atmosphere has already nearly doubled, and the earth's surface is on average about 0.6°C warmer—enough to convince many scientists and laypeople that Arrhenius was right at least about this. In 2001, the official estimate of the Intergovernmental Panel on Climate Change was that we should expect a warming of about 3°C, give or take a few degrees, in the decades ahead.
But today's prophets of climate change are not quite so sanguine as Arrhenius about the prospect of anthropogenic forcing. This is because, according to some models, even a relatively small rise in global mean temperature would result in dramatic changes in local climate patterns. While climate modelers generally agree that farmers in subarctic latitudes will benefit from warmer summers and milder winters, their forecast for the rest of the planet approximates the apocalypse: famine, drought, hurricanes, floods, mass extinctions—the list goes on. Most of these calamities, said to be of such a scale that they could threaten the viability of human civilization, are predicted to result from changes in weather patterns that would follow from rising temperatures in the oceans and the lower atmosphere.
The earth's climate is an extraordinarily complex system, and most climatologists would probably concur that local perturbations cannot be foretold with precision. But given the magnitude of the prospective problem, many pundits and policymakers—with the backing of the scientific establishment—have become less interested in improving our understanding of climate change than in pressing for an immediate solution. By this they mean somehow reducing (or at least stabilizing) the concentration of CO2 in the atmosphere.
This is a difficult proposition, to say the least. About 70 percent of electricity in the United States is generated by the combustion of fossil fuels, mostly coal; our transportation network, which accounts for about a quarter of our greenhouse-gas emissions, is almost entirely dependent on petroleum. The picture in the rest of the world is not much better, as economic pressures dictate the construction of new coal-fired power plants not only in China and India but also in Germany and Eastern Europe. Despite all the fanfare surrounding Russia's ratification of the Kyoto Protocol in November 2004, bringing the treaty into force, most experts agree that, because of relatively modest emissions targets, allowances for international trading of carbon credits, and the exemption of major polluters like China, it will have no discernible impact on global CO2 emissions.
Nevertheless, as the intellectual class has increasingly become convinced of the reality of man-made climate change—recent “converts” range ideologically from Gregg Easterbrook of the liberal New Republic to Ron Bailey of the libertarian Reason—environmentalists have correspondingly stepped up their efforts to build public support for some sort of action. The media now regularly proclaim the impending reality of climate change and encourage alarm. ABC News, offering not so much as a bow toward a scientific approach, recently asked viewers to submit stories about “global warming” in their own communities. Even the July 2006 issue of Condé Nast Traveler, not generally known for coverage of science and technology issues, includes tips for travelers who feel guilty about the damaging emissions generated by their airplane flights.
Among the more serious efforts to sway the debate are two new books, Tim Flannery's The Weather Makers: How Man Is Changing the Climate and What It Means for Life on Earth
2 and Elizabeth Kolbert's Field Notes from a Catastrophe,
3 along with Al Gore's much ballyhooed film, An Inconvenient Truth. Each of these presents a more or less comprehensive view of the scientific case for global warming, and describes in vivid detail some of the changes already attributed to rising temperatures: melting permafrost in Alaska, the crack-up of the Larsen B ice shelf in Antarctica, thinning sea ice in the Arctic, fiercer and more numerous hurricanes in the Atlantic. And each suggests that the threat of global warming is supported by an overwhelming scientific consensus that, in their view, leaves absolutely no room for dissent.
The basic elements of the consensus are relatively easy to comprehend. Indeed, the three most important have already been mentioned. One is that surface thermometers have registered a global mean increase in temperature of about 0.6°C over the last century, give or take 0.15°C. This means that global temperatures are now higher than they have been in at least a thousand years, and perhaps since before the last major ice age. Likewise, atmospheric CO2 has increased from preindustrial levels of around 250 parts per million by volume (ppmv) to around 378 ppmv, a level probably not seen since the Pliocene era, around 3.5 million years ago, when atmospheric CO2 was higher for reasons that are basically unknown. There is little doubt, however, that at least some of the current increase is attributable to human activity.
So much for the data. The rest of what we “know” about global warming comes from intricate computer simulations, called general circulation models (or GCM's), which make use of these data and innumerable other observations about the earth's atmosphere in order to predict the effects of continuing increases in CO2. Almost all the models forecast more warming, with the amount depending on various assumptions built into them. Although it is not clear from these results exactly why we should be alarmed—more on this later—Kolbert, Flannery, and Gore do their best to make sure that we are alarmed, enough to be willing to take drastic action. Each of them takes a slightly different rhetorical tack, but the ultimate message is always the same: we are on the verge of a catastrophe.
Kolbert's book, which grew out of a series of articles written for the New Yorker in 2005, adopts a journalistic style; she reports from the “front lines,” as it were, embedding her essential points in well-crafted vignettes and conversations with scientists. She treks to Alaska, where an expert in permafrost tells her that temperatures have already become dangerously high. In Greenland, she observes cracks and crevasses in the ice sheet, which seem to suggest that the island's glaciers are melting. Experts on mosquitos, frogs, and butterflies attest to ecological changes that similarly portend a warming earth. Some people, it seems, have already bitten the bullet: Kolbert describes how the Dutch are abandoning their 500-year-old battle against the seas, dismantling their dikes and designing floating houses.
Despite its grim tidings, Field Notes is almost a pleasure to read, thanks to Kolbert's casually elegant prose and attention to detail. Indeed, the anecdotal approach makes for a story both more interesting and less convincing than Kolbert might have hoped. By allowing scientists to present the case for global warming in their own words, Kolbert perhaps inadvertently gives the reader a glimpse into the doubts that still exist even among the most ardent believers in the problem—and into those believers' very human biases.
As compared with Field Notes, Tim Flannery's The Weather Makers is more flamboyant, more decisive, and far more belligerent. Flannery, an Australian zoologist and something of a scientific celebrity, does little to hide his contempt for those who fail to take the problem of climate change as seriously as he does.
The Weather Makers starts off on an encouraging note, with an acknowledgment that climate change is difficult to evaluate impartially because the scientific issues are bound up in competing political and economic interests. Unfortunately, this pretense of evenhandedness collapses by the first chapter, which introduces the Gaia hypothesis—roughly, the idea that the earth's oceans, soil, atmosphere, and living creatures function together as a kind of superorganism, resisting changes that would alter the global climate. It is our failure to adopt a Gaian view, Flannery suggests, that has led us into the current global-warming predicament. (James Lovelock, the British scientist who proposed the Gaia hypothesis in the late 1960's, has predicted that global warming will lead to a mass extinction of the human population—a sort of Gaian “final solution” to the problem of anthropogenic pollution.)
In Flannery's view, the “consensus” based on climate change models is too conservative. He thinks that climate change has already taken off in full force, and the outlook for the future is dire indeed. Where Kolbert is circumspect about warming trends at the poles, Flannery suggests that the entire polar ecosystem is on the brink of collapse, and that coral reefs bleached by overheated oceans may never recover. Droughts in the American West, Australia, and Africa are all attributed to global warming, as are Europe's recent heat waves and floods. And this is just the beginning: Flannery predicts a rapid rise in global temperatures that will wipe out innumerable animal and plant species, not to mention agriculture in much of the world.
Is there anything we can do to mitigate the coming disaster? The Weather Makers devotes considerable attention to exploring possible solutions. These include geosequestration (pumping CO2 back into the earth's crust) and alternative energy sources like hydrogen, nuclear, wind, and solar power. Not surprisingly, Flannery comes down on the side of wind and solar power, suggesting that these would be the most economical and democratic choices. Why democratic? Because, he imagines, each community and household can control its own electricity generation with wind farms and solar panels, while alternatives like nuclear power will merely perpetuate corporate control of the power grid.
Flannery reserves his greatest ire for big business, and for the conservative politicians he sees as subservient to it. In the end, he seems to think that if we fail to break free of our captivity to “big oil” and “big coal,” the imperative to regulate the climate will leave us with no choice but to submit to some sort of world government.
Somewhere in-between Kolbert's measured warning and Flannery's hysterical fearmongering lies An Inconvenient Truth. Narrated in its entirety by Al Gore, the film is part documentary, part hagiography: ominous warnings about the threat of climate change are interleaved with flashbacks to Gore's childhood and other formative moments in the former Vice President's career.
The movie covers much of the same ground as Field Notes and The Weather Makers, but with less concern for factual accuracy. Gore all but explicitly blames global warming for the disastrous effects of Hurricane Katrina; even Flannery only goes so far as to offer Katrina as an example of the kind of disaster that might become more prevalent in a warming world, and climatologists themselves are divided over whether global warming implies an increase in tropical-storm activity. In another segment, an animated polar bear is shown swimming for his life in an ice-free Arctic sea. Presumably the filmmakers resorted to animation because, in fact, most polar-bear populations are not under such imminent threat.
Gore's overall strategy is to present the worst of worst-case scenarios as if they were inevitable, barring a miraculous reduction in atmospheric CO2. He suggests, for example, that Greenland's ice cap is in danger of melting, which in turn would cause the jet stream to shut down—a bit like the scenario dramatized in the 2004 disaster film The Day After Tomorrow. Needless to say, most earth and atmospheric scientists consider the likelihood of such an event to be vanishingly low. Animated maps show sea levels rising to inundate Miami, New York, and Shanghai, which is more than even the most extreme predictions would seem to allow.
One might note that An Inconvenient Truth contains more than its share of ironies and curious lacunae. Gore suggests that viewers can help cut back on their own carbon emissions by taking mass transit. And yet, during much of the movie, Gore is shown either riding in a car or traveling on a plane—by himself. He berates Americans for our reliance on fossil fuels, but, chatting amiably with Chinese engineers, seems peculiarly unconcerned by Chinese plans to build hundreds of new coal-fired power plants. Indeed, he compares vehicle-emission standards in the United States unfavorably with China's. Touting “renewable” fuels like those derived from biomass (which at present offer no carbon savings compared with traditional fuels), he does not mention nuclear power or other practical carbon-reducing alternatives to coal, oil, and gas.
In the end, An Inconvenient Truth brings nothing new to the global-warming debate, except perhaps its insistence that the “debate” is over. Its effectiveness as a film—the New York Times has called it “surprisingly engaging”—hinges, one suspects, on the degree to which the viewer is likely a priori to have a favorable view of Al Gore. Those who basically like him, or hope to see him run again for the presidency, have described his performance as earnest and energetic, and have found his appeal persuasive; Franklin Foer, the editor of the New Republic, was so impressed that he pronounced the film likely to become a “seminal political document.” To others, he comes across as a self-absorbed, condescending know-it-all.
Politics aside, however, does Gore have a point? Is it really true that the threat of climate change impels us to take action?
The data themselves—that is to say, actual observations of the earth's climate—are hardly grounds for much excitement. For example, the fact that global temperatures and CO2 levels are correlated in the climatological record is not in itself cause for panic. Consider the “smoking gun” for many global-warming alarmists—the Vostok ice core, an 11,775-foot-long sliver of Antarctic ice that has allowed scientists to extrapolate atmospheric CO2 and temperature anomalies over roughly the past 420,000 years, showing that temperature and CO2 have risen and fallen roughly in tandem over this time frame.
But the key word here is “roughly.” The Vostok data make it clear that at the onset of the last glaciation, temperatures began to decline thousands of years before a corresponding decline in atmospheric CO2. This observation cannot be replicated by current climate models, which require a previous fall in CO2 for glaciation to occur. Moreover, an analysis published in Science in 2003 suggests that the end of one glacial period, called Termination III, preceded a rise in CO2 by 600 to 1,000 years. One explanation for this apparent paradox might be that global warming, whatever its initial trigger, liberates CO2 from oceans and permafrost; this additional CO2 might then contribute in turn to the natural greenhouse effect.
Should we worry that adding even more CO2 to the atmosphere by burning fossil fuels could contribute to a runaway warming effect? Probably not. In simple physical terms, each extra unit of CO2 added to the atmosphere contributes less to the greenhouse effect than the previous unit, just as extra layers of paint applied to a pane of glass contribute less and less to its opacity. For this reason, we have already experienced 75 percent of the warming that should be attributable to a simple doubling of atmospheric CO2 since the late 19th century, a benchmark we have not yet reached but one that is frequently cited as dangerous by those who fear global warming. Moreover, it seems unlikely that we can do very much about it.
Most models, of course, predict much more warming to come. This has to do with the way they account for the effects of clouds and water vapor, which are assumed to amplify greatly the response to man-made greenhouse gases. The problem with this assumption is that it is probably wrong.
Many scientists who study clouds—including MIT's Richard Lindzen, a prominent skeptic of climate-change alarmism—argue that the data show the opposite to be true: namely, that clouds act to limit, rather than aggravate, warming trends. In any case, the GCM's have failed miserably to simulate observed changes in cloud cover. Flannery, to his credit, is cognizant of this criticism, and acknowledges that the role of clouds is poorly understood. By way of a response, he draws attention to a computer simulation showing a high degree of correspondence between observed and predicted cloud cover for one model on a single day—July 1, 1998. Overall, however, GCM simulations of clouds are a source of significant error.
Indeed, the models are subject to so much uncertainty that it is hard to understand why anyone would bother to get worked up about them. Generally speaking, the GCM's simulate two kinds of effects on climate: natural forcing, which includes the impact of volcanic eruptions and solar radiation, and anthropogenic forcing, which includes greenhouse gases and so-called aerosols, or particulate pollution. But the behavior of most of these factors is unknown.
The major models assume, for example, that aerosols act to cancel warming; this effect is said to “explain” the apparent decline in global temperatures from the 1940's to the 1970's, when the popular imagination was briefly obsessed with the possibility of global cooling. Some scientists, however, are now claiming that the opposite is true, and that aerosols actually exacerbate warming.
Whatever the case, the impact of aerosols is so poorly understood that the term essentially refers to a parameter that can be adjusted to make the models' predictions correspond to actual observations. Making inferences from the models about the “true” state of the earth's climate is therefore an exercise in circular reasoning. To be sure, the business of fine-tuning GCM's provides a livelihood for many climatologists, and may one day yield valuable insights into the workings of the earth's climate. But the output of these models is hardly a harbinger of the end of civilization.
If the empirical basis for alarmism about global warming is so flimsy, it is reasonable to ask what can account for the disproportionately pessimistic response of many segments of society.
Part of the problem is that global warming has ceased to be a scientific question—by which I do not mean that the interesting scientific issues have actually been settled, but that many of those concerned about global warming are no longer really interested in the science. As Richard Lindzen has reminded us, the Kyoto Protocol provides an excellent illustration. Although there is widespread scientific agreement that the protocol will do next to nothing to affect climate change, politicians worldwide continue to insist that it is vital to our efforts to combat the problem of global warming, and scientists largely refrain from contradicting them.
Some have suggested that the underlying reason for this is economic. After all, public alarm is a powerful generator of science funding, a fact that is not lost on theorists and practitioners. In 2003, the National Research Council, the public-policy arm of the National Academy of Sciences, criticized a draft of the U.S. National Climate Change Plan for placing too much emphasis on improving our knowledge about the climate and too little on studying the likely impacts of global warming—the latter topic being sure to produce apprehension, and hence grants for more research. By the same token, the Kyoto process seems to lumber on in part because of the very large number of diplomats and bureaucrats whose prestige and livelihoods depend on maintaining the perception that their jobs are indispensable.
Money aside, it may be that many scientists have a knack for overinterpreting the importance of their own work. It is of course exciting to think that one's research concerns an unprecedented phenomenon with far-reaching political implications. But not only can this lead to public misperception, it can encourage a politicization of the scientific literature itself. Scientists skeptical of the importance of anthropogenic warming have testified that it is difficult to publish their work in prestigious journals; when they do publish, their articles are almost always accompanied by rebuttals.
In fact, the scientific “consensus” on climate change—at least, as it is summarized by Gore, Flannery, and the like—includes a very large number of disparate observations, only a small number of which are pertinent to understanding the actual determinants of contemporary climate change. The fact, for example, that certain species have become scarce or extinct is frequently presented as a cause for alarm about the climate. But such ecological shifts are often the result of idiosyncratic local conditions, and in any case are largely irrelevant to the broader issue of global warming.
In recent years the issue of climate change has also been used as a tool to embarrass the political Right, and especially the Bush administration—which, after Bill Clinton declined to submit the Kyoto Protocol to the Senate for ratification, withdrew the U.S. signature from the pact. Although efforts to portray conservatives as insensitive to environmental issues are not new, what is new is the scope of the alleged problem, which requires not merely a targeted solution (like the phasing-out of chlorofluorocarbons in response to ozone depletion) but a radical change in our mode of energy generation and specifically a wholesale shift away from fossil fuels.
The really curious element here is that many of those who seem to have become convinced of the reality of climate change appear rather unwilling to take meaningful steps toward cleaner sources of energy. Like Flannery, they simply assert that a carbon-free economy will somehow be much more efficient and productive than one powered by fossil fuels—because, of course, we will be rid of evil and greedy energy companies, which many alarmists suspect are at the root of the problem.
Practically speaking, however, they have little to offer. Very few Democratic politicians have advocated the construction of new nuclear-power plants, a key element of the Bush administration's energy plan and probably our best bet to avoid an increased reliance on coal. Although Senator Edward M. Kennedy (among other Democrats) signed a bill that would require the U.S. to derive 20 percent of its energy from renewable sources by 2020, he has strenuously opposed a wind farm planned off the coast of Cape Cod, visible from his Hyannisport family estate.
The overall effect of these inconsistent policy goals—limiting fossil-fuel consumption without activating any viable substitutes—will be to drive up the price of energy, a move that will probably not much affect the affluent but will be quite problematic for the rest of us. Al Gore will be able to continue to crisscross the country by jet, while feeling virtuous about having encouraged the shift worker to reduce his energy consumption by using public transportation. And if the problem of global warming does not eventuate, so much the better. Alarmists will be able to reassure themselves that they have forestalled a catastrophe, even if this comes at considerable expense to the economy as a whole.
There are many good reasons to wean ourselves from a dependence on fossil fuels, not least to cease enriching unsavory regimes in places like Saudi Arabia, Iran, and Venezuela. But in combating climate change, we should not ignore the damage done by the proponents of global-warning themselves in diverting money and energy away from more obvious and well-substantiated problems. Unfortunately, many people seem to be more concerned with the supposed menace of global warming, about which we can realistically do very little, than with problems like infectious disease, about which we can do quite a bit. Speaking of inconvenient truths, this is a real one.
1 Technically speaking, the greenhouse effect refers to the warming attributable to all greenhouse gases, including not only CO2 but also water vapor, methane, and others. The contribution to the greenhouse effect of CO2 produced by combustion is properly called the Callendar effect, after the British scientist, Guy Stewart Callendar, who proposed it in 1938.
2 Atlantic Monthly Press, 384 pp., $24.00.
3 Bloomsbury USA, 192 pp., $22.95.