The year 2005 has been the hottest year on record for the planet, hotter than 1998, 2002, 2004, and 2003. More importantly, perhaps, this has been the autumn when the planet has shown more clearly than before just what that extra heat means. Consider just a few of the findings published in the major scientific journals during the last three months:
—Arctic sea ice is melting fast. There was 20 percent less of it than normal this summer, and as Dr. Mark Serreze, one of the researchers from Colorado’s National Snow and Ice Data Center, told reporters, “the feeling is we are reaching a tipping point or threshold beyond which sea ice will not recover.” That is particularly bad news because it creates a potent feedback effect: instead of blinding white ice that bounces sunlight back into space, there is now open blue water that soaks up the sun’s heat, amplifying the melting process.
—In the tundra of Siberia, other researchers report that permafrost has begun to melt rapidly, and, as it does, formerly frozen methane—which, like the more prevalent carbon dioxide, acts as a heat-trapping “greenhouse gas”—is escaping into the atmosphere. In some places last winter, the methane bubbled up so steadily that puddles of standing water couldn’t freeze even in the depths of the Russian winter.
—British researchers, examining almost six thousand soil borings across the UK, found another feedback effect. Warmer temperatures (growing seasons now last eleven days longer at that latitude) meant that microbial activity had increased dramatically in the soil. This, in turn, meant that much of the carbon long stored in the soil was now being released into the atmosphere. The quantities were large enough to negate all the work that Britain had done to switch away from coal to reduce carbon in the atmosphere. “All the consequences of global warming will occur more rapidly,” said Guy Kirk, chief scientist on the study. “That’s the scary thing. The amount of time we have got to do something about it is smaller than we thought.”
Such findings—and there are more like them in virtually every issue of Science and Nature—came against the backdrop of Hurricanes Katrina and Rita, and the now record-breaking Atlantic storm season that has brought us back around the alphabet and as far as Hurricane Epsilon. Because hurricanes draw their power from the warm water in the upper layers of the sea’s surface, this bout of storminess served as a kind of exclamation point to a mid-August paper by the MIT researcher Kerry Emmanuel demonstrating that such storms have become more powerful and long-lasting, and would likely continue to increase in destructiveness in the future.
But the hurricanes also demonstrated another fact about global warming, this one having nothing to do with chemistry or physics but instead with politics, journalism, and the rituals of science. Climate change somehow seems unable to emerge on the world stage for what it really is: the single biggest challenge facing the planet, the equal in every way to the nuclear threat that transfixed us during the past half-century and a threat we haven’t even begun to deal with. The coverage of Katrina’s aftermath, for instance, was scathing in depicting the Bush administration’s incompetence and cronyism; but the President—and his predecessors—were spared criticism for their far bigger sin of omission, the failure to do anything at all to stanch the flood of carbon that America, above all other nations, pours into the atmosphere and that is the prime cause of the great heating now underway. Though Bush has been egregious in his ignorance about climate change, the failure to do anything about it has been bipartisan; Bill Clinton and Al Gore were grandly rhetorical about the issue, but nonetheless presided over a 13 percent increase in America’s carbon emissions.
That lack of preparation and precaution dwarfs even the failure to prepare for the September 11 attacks, and its effects will be with us far longer. It’s not, of course, that America could in two decades have prevented global warming. But we could have begun taking the steps to keep it from spinning entirely out of control, steps that grow ever more difficult to take with each passing season. The books under review, though neither deals directly with the politics of global warming, help us understand some of the reasons why we’ve so far done so little.
The best of the two—indeed, one of the best books yet published on climate change—is Mark Bowen’s Thin Ice, which describes the science of global warming through the experience of the Ohio State University scientist Lonnie Thompson, the preeminent explorer of tropical and semitropical glaciers today, and the principal decoder of the secrets trapped in their ice. A minor defect is that the book was clearly designed to sell to readers of Jon Krakauer’s classic Everest account, Into Thin Air—the title and the cover are bizarrely similar. And because of that decision, too much space is devoted to Thompson’s adventures in the “death zone” above 18,000 feet on various Andean and Himalayan peaks, and too many tales are told about the Sherpas who make the expeditions possible and the hot-air balloons designed to float ice cores back to the base of the mountain before they could melt. These stories make the book needlessly long and distractingly repetitive, and detract a little from its emphasis on glaciers and what is happening to them.
But only a little. Bowen is one of the few people who could have written this book. Himself an expert climber who has written for popular magazines like Climbing, he also has a Ph.D. in physics from MIT. He has been able to climb mountains along with Thompson to examine the glaciers and explain both the scientific and political consequences of their melting.
For many years, scientists trying to reconstruct past climate history have studied glaciers. Since each year’s snowfall lies in a distinct layer, a core sample from such an ice field can be read much like a tree ring to distinguish long-term trends in weather. Moreover, small bubbles of air trapped in the ice can be sampled to provide a record of atmospheric conditions from any time in the past. One can tell from them how much carbon dioxide was in the atmosphere and what the weather was like—a Siberian core extracted in the 1980s demonstrated a perfect correlation between fluctuations in temperature and carbon dioxide levels and helped to embolden a few researchers to make the first global warming forecasts with real confidence.
For many years, researchers concentrated on taking core samples from alpine and polar ice—they were relatively easy to get to, and no one thought that high mountain ice in the equatorial zones would yield much interesting information because the tropics were seen as unvarying from year to year and hence climatologically dull. But beginning in the 1970s Thompson and his team began perfecting the techniques of drilling long, thin cores from the high and wild glaciers of Peru, Ecuador, Nepal, and Tibet, and then examining them in their laboratory in Columbus. They also began to translate the information latent in the cores.
The aim of their research was to figure out what had driven changes in the earth’s climate in the past—how and why ice ages emerged and retreated, why there have been smaller but abrupt swings back and forth in climate even during the current interglacial period. Thompson has done much to demonstrate that changes in tropical regions—which account, after all, for half the world’s surface—drive the process. Many of his findings conflicted with other research that seemed to show that events in the north Atlantic—particularly the waxing and waning of warm deep ocean currents—were the chief cause of rapid climate change in times past.
An immense amount of scientific effort (and, as Bowen makes amusingly clear, scientific vitriol) has been spent on this topic, with much debate about whether the principal causes of climate change have been in the Gulf Stream or the Indonesian Warm Pool or somewhere else altogether. But what eventually becomes clear, as Bowen tells this long story, is essentially how irrelevant it is to the current climate problem. By burning coal and gas and oil in such enormous amounts, we have raised the carbon dioxide level in the atmosphere far above what it has ever been during even the very long period one can study with ice cores. As such, a brand-new experiment is taking place, one that is out of control.
The second half of Bowen’s book, interspersed throughout his tale of adventure at high altitudes but only loosely related to Thompson and his fieldwork, is a history of the realization that a vast change was taking place. It is the best compact history of the science of global warming I have read. Bowen begins, appropriately, with nineteenth-century scientists like John Tyndall and Svante Arrhenius, Europeans who began to understand how carbon dioxide acted as a heat-trapping gas in the atmosphere and who began to worry about the amounts of it that a newly industrialized society was spewing out of its stacks.
The story takes on more urgency in the 1950s, when oceanographers like Roger Revelle and Hans Suess undertook more concentrated speculation and when the environmental scientist Charles Keeling investigated the effects of CO2, taking actual measurements with a CO2 detector on the slopes of Mauna Loa in Hawaii.1 He was soon able to show that the gas was indeed accumulating in the atmosphere, and doing so rapidly. (Pre–industrial revolution concentrations of CO2 were about 275 parts per million; by the late 1950s the number was 315, and today it is nearly 380.)
The story of greenhouse science continued in the 1970s and 1980s, as scientists began developing global climate models that attempted to forecast what the new chemicals would mean for the planet. And it reached a high point in the early summer of 1988 when one of the most important of those climate modelers, a NASA scientist named James Hansen, appeared before a hearing of the Senate Committee on Energy and Natural Resources. The United States was enduring one of the great heat waves in its history:
Barges were stranded by the thousands in the Mississippi River. Civil War vessels last seen when Confederate troops scuttled them on their retreat from Vicksburg rose above the surface of the Big Muddy, a Mississippi tributary. The West experiences the worst forest fires in recorded history.
Against that backdrop, Hansen was given fifteen minutes to testify. He made three points: that he was “99 percent confident” that the earth was warming; that the warming could be traced with “a high degree of confidence” to the greenhouse effect; and that in his model the greenhouse effect was already strong enough to increase the odds of extreme summer heat and drought in the US. He was careful not to say that the heat wave of 1988 was the result of global warming (a claim that would never be possible for any particular hot spell or drought or hurricane); but he said something very important to a group of reporters as he left the hearing: “It’s time to stop waffling so much and say that the greenhouse effect is here and is affecting our climate now.”
Keeling and Thompson were jointly honored with this year's prestigious Tyler Prize for Environmental Achievement.↩
Keeling and Thompson were jointly honored with this year’s prestigious Tyler Prize for Environmental Achievement.↩