The coming meltdown

The media and public were transfixed by the nuclear threat of the second half of the 20th century - so why aren't they more concerned about climate change, the single biggest challenge facing the planet today? Bill McKibben reports on recent evidence for global warming, and why scientists have struggled to convince us that its happening.

The year 2005 was the hottest year on record for the planet, hotter than 1998, 2002, 2004, and 2003. More importantly, perhaps, this was the year when the planet showed more clearly than before just what that extra heat means (see accompanying panel on recent global warming "highlights").

Yet 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 per cent 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.

Mark Bowen's Thin Ice describes the science of global warming through the experience of the Ohio State University scientist Lonnie Thompson, the pre-eminent explorer of tropical and semitropical glaciers today, and the principal decoder of the secrets trapped in their ice.

Bowen is one of the few people who could have written this book. Himself an expert climber, he also has a PhD 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.

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 has been spent on this topic. But what eventually becomes clear 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 is a history of the realisation that a vast change was taking place. The story of greenhouse science reached a high point in the early summer of 1988 when one of the most important of the 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. The West experienced 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 per cent 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.

That was the moment at which the greenhouse era really began. As a NASA employee, Hansen had shown great courage in speaking straightforwardly, which earned him endless trouble from his bosses in the federal government. But it also earned him contempt from his fellow scientists. In Bowen's words:

"They all objected to his simplification, his lack of caution, his disregard for the formal, highly qualified – one could even say codified – manner in which scientific conclusions are stated in the peer-reviewed journals."

If Hansen had succeeded temporarily in putting the issue before the public in 1988, "other forces had quickly swept it away", writes Bowen. Some of those forces came from industry. The coal and oil industry took up the work of disinformation in earnest, finding a few scientists and scientific hangers-on to write Op-Ed pieces and appear on talk shows to provide a "balanced" view. Journalism proved unequal to the task of separating scientific consensus from minor or trivial dissent; almost every story about global warming was accompanied by an obligatory statement of denial.

Science, on the other hand, both rose to the occasion and failed badly. The world's climatologists organised themselves into the Intergovernmental Panel on Climate Change, or IPCC, in those heady months of 1988. With large government funding that was partly made available because of Hansen's warnings, the panels of experts soon had a vast collection of studies and computer models to pore over. And though the IPCC's procedures were byzantine – they relied, Bowen writes, on "a peer review process... incalculably more cumbersome than anything ever applied to a scientific issue before" – the group eventually managed to reach a potent conclusion. By 1995, the IPCC was ready to conclude that "the balance of evidence suggests that there is a discernible human influence on global climate". This result was remarkable: more than a thousand scientists, working through a process that allowed much political input from governments concerned to deny global warming, nonetheless found the evidence so overwhelming that they were able to state that one species, ours, was now changing pretty much everything on the face of the planet.

But at the same time, the conclusions were watered down and over-hedged, playing at least as much into the hands of the few remaining skeptics, who seized on every possible opportunity to dampen public concern. The scientific method, pursued in this fashion, seemed unequal to the gravity of the task at hand. Bowen writes, "I believe it is fair to say that serious scientific debate about the existence and potential danger of human-induced global warming died with that statement". That is true - but it's also true that it contributed remarkably little to the larger public debate, especially in the US. And that's a failure for which scientists bear some of the blame.

Bowen quotes Hansen:

"The scientific method does require that you continually question the conclusions that you draw and put caveats on the conclusion – but that can be misleading to the public. It seems to me that when we talk to the public we have to try to give a summary. And it's not easy for most scientists to do – and not easy for me."

Thompson's most important scientific contribution is his simplest: by going back year after year to tropical glaciers in order to take core samples for his "real" work, he has been able to document the astonishing speed with which those glaciers are disappearing. His photographs documenting this trend have been valuable in persuading people to take global warming seriously. There is something alarming and undeniable about change occurring across the globe that can be measured from one year to the next, for instance, the Qori Kalis glacier on Quelccaya, which Thompson has been visiting for thirty years: Thompson estimates that the entire Quelccaya ice cap, which 30 years ago covered 27 square miles and was 500 feet deep at its 18,000-foot summit, will die before he does.

Perhaps Thompson's most dramatic contribution to the public debate over global warming came in February 2001 when he told a session at the annual meeting of the American Association for the Advancement of Science that the snows on the top of Mt Kilimanjaro would disappear within twenty years and that "little can be done to save them". That image stuck in people's minds – it was at least as important as the near-simultaneous release of the IPCC's next assessment, which was more forthright than ever in its declaration that "most of the warming observed over the last 50 years is attributable to human activities" and in its prediction that the planet's average temperature might increase as much as ten degrees Fahrenheit before the century was out.

But by that point George Bush had been elected president of the United States, and the issue of climate change had disappeared almost entirely – and with it the chance of altering the early trajectory of development in India and particularly China, which are now starting to rival American contributions to the earth's carbon overload.

If the dry language of science has sometimes been an impediment to action, the language of emotion has its own dangers, as can be seen from Alanna Mitchell's Dancing at the Dead Sea, a book thick with sentiment.

Still, Mitchell raises an important question. Every time she corners a scientist – the veteran Oxford environmental researcher Norman Meyers, the great diver and marine biologist Sylvia Earle, the eminent conservationist Russell Mittermeier – she asks: "Are humans a suicidal species?" They mostly dismiss her question with some reassuring words to the effect that we can still make up our minds to do better. But in fact it's a question that in some way or another needs to be near the centre of our public debates. It rose for the first time in the wake of Hiroshima and Nagasaki; for a while, many people seemed to expect an Armageddon-like nuclear exchange, and then they seemed to discount the possibility. The attacks on New York and Washington at the beginning of this millennium have raised the question of our being a suicidal species again.

It is also the question raised by our environmental predicament, and Mitchell deserves credit for risking the scorn of reviewers by bringing it into the open. She quotes President Bush, a few weeks after taking office, explaining why he's opting out of the Kyoto protocols, the only official international attempt to deal with global warming:

"I will explain as clearly as I can, today and every other chance I get, that we will not do anything that harms our economy... That's my priority. I'm worried about the economy."

It's not as if Bush is alone in this thought. And it does seem to epitomise the danger that the satisfactions of consumer life and business success have become almost sacred while the physical world now turning to chaos before our eyes is taken for granted, and not seen as the reality that must be faced.

This winter, we are forced to face the fact that a century's carelessness is now melting away the world's storehouses of ice, a melting whose momentum may be nearing the irreversible. It's as if we were stripping the spectrum of a color, or eradicating one note from every octave. There are almost no words for such a change: it's no wonder that scientists have to struggle to get across the enormity of what is happening. p

© The New York Review of Books