With Speed and Violence: Why Scientists Fear Tipping Points in Climate Change (6 page)

A report from the U.S. National Academy of Sciences in 2002, under the chairmanship of Richard Alley, of Penn State University-a glaciologist with the slightly manic appearance of an ex-hippie, who has become a regular on Capitol Hill for his ability to talk climate science in plain language-sounded a similar warning. "Recent scientific evidence shows that major and widespread climate changes have occurred with startling speed," the report began. "The new paradigm of an abruptly changing climate system has been well established by research over the last decade, but this new thinking is little known and scarcely appreciated in the wider community of natural and social scientists and policymakers." Or, Alley might have added, among the citizens of this threatened planet.

We have already had one lucky break. It happened twenty years ago, when a hole suddenly opened in the ozone layer over Antarctica, stripping away the continent's protective shield against ultraviolet radiation. We were lucky that it happened over Antarctica, and lucky that we spotted it before it spread too far.

Many of the scientists who worked to unravel the cause of the ozone hole-including Crutzen, who won his Nobel Prize in this endeavor-are among the most vehement in issuing the new warnings. They know how close we came to disaster. Glaciologists like Alley are another group who take the perils of the Anthropocene most seriously. In the past decade, they have analyzed ice cores from both Greenland and Antarctica to map the patterns of past natural climate change. The results have been chilling.

It has emerged, for instance, that around 12,000 years ago, as the last ice age waned and ice sheets were in full retreat across Europe and North America, the warming abruptly went into reverse. For a thousand years the world returned to the depths of the ice age, only to emerge again with such speed that, as Alley puts it, "roughly half of the entire warming between the ice ages and the postglacial world took place in only a decade." The world warmed by at least 9 degrees-the IPCC's prediction for the next century or so-within ten years. This beggars belief. But Alley and his coresearchers are adamant that the ice cores show this happened.

Similar switchback temperature changes occurred regularly through the last glaciation, and there were a number of other "flickers" as the planet staggered toward a new postglacial world. Stone Age man, with only the most rudimentary protection from a climatic switchback, must have found that tough. Heaven knows how modern human society would respond to such a change, whereby London would have a North African climate, Mexican temperatures would be visited on New England, and India's billionplus population would be deprived of the monsoon rains that feed them.

The exact cause of the rise and fall of the ice ages still excites disputes. But it seems that the 100,000-year cycles of ice ages and interglacials that have persisted for around a million years have coincided with a minor wobble in Earth's orbit. Its effect on the solar radiation reaching the planet is minute, and it happens only gradually. But somehow Earth's systems amplify its impact, turning a minor cooling into an abrupt freeze or an equally minor warming into a sudden defrost. The amplification certainly involves greenhouse gases, as Arrhenius long ago surmised. The extraordinary way in which temperatures and carbon dioxide levels have moved in lockstep permits no other interpretation. It also probably involves changes to ocean currents and the temperature feedbacks from growing and melting ice.

We will return to this conundrum later. What matters here is that a minor change in the planet's heating-much less, indeed, than we are currently inflicting through greenhouse gases-could cause such massive changes worldwide. The planet seems primed to leap into and out of glaciations and, perhaps, other states too.

Some see this hair trigger as rather precisely organized. Will Steffen says that for a couple of million years, Earth's climate seems to have had just two "stable states": glacial and interglacial. There was no smooth transition between them. The planet simply jumped, at a signal from the orbital wobble, from the glacial to the interglacial state, and made the jump back again with a little, but not much, more decorum. "The planet jumps straight into the frying pan and makes a bumpy and erratic slide into the freezer," Steffen says. The glacial state seems to have been anchored at carbon dioxide levels of around 19o ppm, while the interglacial state, which the modern world occupied until the Industrial Revolution, was anchored at about 280 ppm. The rapid flip between the two states must have involved a reallocation of about 22o billion tons of carbon between the oceans, land, and the atmosphere. Carbon was buried in the oceans during the glaciations and reappeared afterward. Nobody knows quite how or why. But the operation of the hair-trigger jump to a much warmer state raises critical questions for the Anthropocene.

In the past two centuries, humanity has injected about another 22o billion tons of carbon into the atmosphere, pushing carbon dioxide levels up by a third, from the stable interglacial level of 28o ppm to the present 380 ppm. The figure continues to rise by about 20 ppm a decade. So the big question is how Earth will respond. Conventional thinking among climate scientists from Arrhenius on predicts that rising emissions of carbon dioxide will produce a steady rise in atmospheric concentrations and an equally steady rise in temperatures. That's still the IPCC story. But Steffen takes a different view: "If the ice age seemed to gravitate between two steady states, maybe in future we will gravitate to a third steady state." Nature might, he concedes, fulfill the expectations of climate skeptics and push back down toward 28o ppm; but if it was going to do that, we would already see evidence of it. And we don't.

Other scientists, including Alley, are not convinced by Steffen's sense of order in the system. Sitting in his departmental office, Alley likens the climate system to "a drunk-generally quiet when left alone, but unpredictable when roused." When he is writing scientific papers or committee reports, his language is not so vivid. He talks of a "chaotic system" vulnerable to "forcings" from changes in solar radiation or greenhouse gases. "Abrupt climate change always could occur," he says. But "the existence of forcings greatly increases the number of possible mechanisms [for] abrupt change"; and "the more rapid the forcings, the more likely it is that the resulting change will be abrupt on the timescale of human economies or global ecosystems." Drunks, in other words, may be unpredictable, but if you shout at them louder or push them harder, they will react more vehemently. Right now, moreover, we are offering our drunk one more for the road.

The past io,ooo years, since the end of the last ice age, have not been without climate change. The Asian monsoon has switched on and off; deserts have come and gone; Europe and North America have flipped from medieval warm period to little ice age. None of these events has been as dramatic as the waxing and waning of the ice ages themselves. But most were equally abrupt, and civilizations have come and gone in their wake. Even so, human society in general has prospered, learning to plant crops, domesticate animals, tame rivers, create cities, develop science, and ultimately industrialize the planet.

But in the Anthropocene, the rules of the game have changed. Alley and Steffen agree that humanity is today pushing planetary life-support systems toward their limits. The stakes are higher, because what is happening is global. "Before, if we screwed up, we could move on," says Steffen. "But now we don't have an exit option. We don't have another planet."

5

THE WATCHTOWER

Keeping climate vigil on an Arctic island

A chill wind was blowing off the glacier. Small blue chunks of ice occasionally split from its face and floated down the fjord toward the ocean. A strange green ribbon of light flashed across the sky above from an anonymous building on the foreshore. And on the snow behind, a polar bear wandered warily around a strange human settlement that had grown up on this remote fjord at the seventy-ninth parallel.

I had come to Ny-Alesund, an international community of scientists that, in the darkening days of autumn, numbered fewer than thirty people. The hardy band was there to man this Arctic watchtower on the northwest shores of Spitzbergen, the largest island of a cluster of Arctic islands called Svalbard, because it is reckoned to be one of the most likely places to witness firsthand any future climatic conflagration. Hollywood directors may have chosen New York as the place that would descend into climatic chaos first. But while the scientists here heartily enjoy watching their DVD of The Day After Tomorrow, they are convinced that NyAlesund is the place to be. The place where our comfy, climatically benign world might begin to end. Where nature may start to take its revenge.

Ny-Alesund is a tiny town of yellow, red, and blue houses two hours' flight from the northernmost spot on mainland Europe. It is nearer Greenland and the North Pole than Norway, which administers Svalbard under an international treaty signed in 1920. It has history. This was where great Norwegian Arctic explorers such as Roald Amundsen and Graf Zeppelin set out for the North Pole, by ship, seaplane, and even giant airship assembled here. More recently, the High Arctic was famous for its military listening posts, where the staff sat in the cold silence, waiting for the first sign of a Russian or American nuclear missile streaking over the ice to obliterate New York or Moscow or London. But today the biggest business is climate science-waiting for the world to turn. Says Jack Kohler, of the Norwegian Polar Institute, down south in Tromso: "If you want to see the world's climate system flip, you'd probably best come here to see it first."

Spitzbergen is already one of the epicenters of climate change. For a few days in July 2005, the scientists put aside their instruments, donned T-shirts and shorts, and sipped lager by the glaciers in temperatures that hit a record 68"F-just 6oo miles from the North Pole. Even in late September, as the sun hovered close to the horizon and the long Arctic night beckoned, the sea was still ice-free, and tomatoes were growing in the greenhouse behind the research station kitchens. Old-timers like the British station head Nick Cox, who has visited Ny-Alesund most years since 1978, marvel at the pace of change. "It stuns me how far the glaciers have retreated and how the climate has changed," Cox says. "It used to be still and clear and cold. Now it is a lot warmer, and damper, too, because the warmer air can hold more moisture."

Photographs in the town's tiny museum show families who used to work in coal mines here in the i93os, huddled in warm clothes down by the shore. Looming behind them are glaciers that are barely visible today, having retreated about 3 miles back up the fjord. The glaciers and ice sheets that still cover two thirds of Svalbard are some of the best-studied in the world. And visiting glaciologists leave each time with worsening news. In the summer of 2005, British glaciologists discovered that the nearby Midtre Lovenbreen glacier had lost 12 inches of height in a single week as it melted in the sun. The Kronebreen glacier may be dumping close to 200,000 acre-feet of ice into the fjord every year.

Jack Kohler is attempting a "mass balance" of the ice of Svalbard. He reckons that 20 million acre-feet melts and runs off into the ocean each year now. Another 3 million acre-feet is lost from icebergs slumping into the sea from 620 miles of ice cliffs. At most, half of this loss is being replaced with new snow. That is an annual net loss of around i i million acre-feeta staggering volume for a small cluster of islands, and probably second in the Arctic only to the loss from the huge ice sheet covering Greenland. And there is more to come, Kohler says. Many of Svalbard's glaciers and ice caps are close to the freezing point and "very sensitive to quite small changes" in temperature. Boreholes drilled into the permafrost show a staggering 0.7°F warming in the past decade. A few more tenths of a degree could be catastrophic, he says.

Ny-Alesund is a cosmopolitan community, especially in summer, with Norwegians and Germans, Swedes and British, Spanish and Finns, Italians and French, Russians and Americans, Japanese and Chinese and Koreans. It is also quirky. Checking some equipment in the empty Korean labs, I found a pair of Spanish scientists hiding there. They said they couldn't afford the accommodation fees in the main compound, but couldn't bear to give up their work measuring glaciers. The Chinese had departed for the winter, but left behind a pair of two-ton granite lions to guard the entrance to their building. The week before, a shipload of Scotsmen, dressed in kilts and offering whiskey galore, showed up at the quayside for some R&R while investigating the sediments on the bottom of the fjord; and since then some Yorkshiremen had flown a remote-controlled helicopter the size of a small dog over glaciers to map them in 3D.

At Ny-Alesund there are magnetometers and riometers and spectrophotometers probing the upper atmosphere; there are weather balloons aplenty, a decompression chamber for divers, and even a big radio telescope that measures the radiation from distant quasars with such accuracy that it helps correct global positioning systems for the effects of continental drift. The scientists here measure chlorofluorocarbons (CFCs) and carbon dioxide, mercury and ozone, water vapor and radon; they fingerprint the smoke and dust brought in on the breeze to find out where they came from; they photograph the northern lights and sniff for methane from the melting tundra. On some cloudless nights, the German researcher Kai Marholdt sends that green shaft of laser light into the sky to probe the chemistry of the stratosphere. There is so much scientific equipment littering the tundra that nobody is sure what is still in use and what has been abandoned by long-since-departed researchers. There are plans for a cleanup, because passing reindeer keep getting tangled in the cables.

Meanwhile, the bears are coming. As the sea ice disappears, polar bears that live out on the ice and hunt for seals are being forced ashore. They are becoming bold. They break into the huts dotting the island, which are maintained for scientists spending a night out on the ice. They are looking for meat, but will sink their teeth into anything soft-bed mattresses and even inflatable boats have been torn to shreds. Anyone moving out of Ny-Alesund has to carry a gun.