| THIN ICE Unlocking the Secrets of Climate in the World's Highest Mountains Mark Bowen New York: Henry Holt & Co., October 2005 |
Rating: 5.0 High |
|||
| ISBN-13 978-0-8050-6443-8 | ||||
| ISBN-10 0-8050-6443-5 | 463pp. | HC/FCI | $30.00 | |
Extracting useful cores from high atop a mountain in the tropics is a dicey proposition. Quite aside from the risks of climbing accidents, altitude sickness, fierce weather,1 there is a strong possibility that melting will have washed out any climate data the ice might once have contained. This was the situation on three peaks Thompson surveyed in the eastern Himalaya, where melting is running ahead of the rest of the world.
The scientific reward for obtaining a good core is a virtual almanac for that location. Bubbles in its layers trap samples of the atmosphere from the year they were laid down. The ratio of oxygen isotopes in the trapped gases can be used to infer temperature. This temperature can be correlated with the measured CO2 concentration. The thickness of each layer indicates the relative amount of precipitation at that time. Finally, the presence of abnormal amounts of dust suggests a period of drought.
Think of the highest peaks of our planet, and your mind fills with images of snow-capped rocky crags lashed by bone-chilling winds. More than the polar regions, such mountains are for most the archetypes of perpetually frozen realms.
But this conventional wisdom is changing faster than we realize. The snows of Kilimanjaro, immortalized by Ernest Hemingway, will be gone by 2015 if Lonnie Thompson is correct. All over the world, mountain glaciers are melting at increasing rates.
The disappearance of these glaciers may bring the first substantial harm definitely traceable to global warming. They are the principal water sources for high-altitude communities from the Himalaya to the Andes. Many lowland communities, too, depend on mountain glaciers. The Ganges flows from the Himalaya, the Amazon from snows in the Bolivian Andes.
Evidence for this comes in from all over the globe. At Britain's Rothera Station, on the west shore of the Antarctic Peninsula, temperatures rose 20°F in the last quarter of the twentieth century. (P. 33) Alaska has warmed by about 5° in the last thirty years. (p. 34) Bird species are moving north. (p. 51) Mark Dyurgerov's 2001 study showed that mountain glaciers had begun to melt in the late 1970s. (p. 79) Twenty feet down in the Tien Shan's Gregoriev Glacier, Thompson's team read a temperature 4°F higher than a Soviet team found 28 years earlier. (p. 214)
(But the interpretation of dust can be tricky, as Thompson found in Peru. Analysis of the cores he brought back from Quelccaya revealed two 130-year periods of abnormal amounts of fine dust, such as might come from the desiccated shores of a shrinking lake in times of little rainfall. But this was contradictory: the dusty layers came from times when rain was plentiful. Neither were they aligned with volcanic eruptions. Also the dust from an eruption would be washed from the air in just a few years. The contradiction was resolved when Thompson realized that human agency was responsible. The Tiwanaku people of Bolivia's Altiplano had built an extensive irrigation system of canals and mounds to support their crops. It was the dust from this massive construction project that Thompson detected. Interestingly, this system was twice as productive as the best twentieth-century methods, required no expensive modern materials, and protected its crops against frost into the bargain. However, it pushed Tiwanaku population high enough so a prolonged drought wiped out that civilization.2, 3)
Together with other evidence derived from dendrochronology (study of the varying widths of tree rings), sediments in lakes and oceans, pollen counts, coral reefs, and diatoms, as well as from archaeological evidence and historical accounts of the advance and decline of civilizations like the Tiwanaku, ice cores enable scientists to reconstruct a fairly complete record of our planet's climate in past epochs. They are discovering that climatic changes are a major factor in the rise and fall of such civilizations. While most can adapt to some degree of change, extreme privation such as a long drought will doom any civilization. This, of course, bodes ill for our own civilization.
Consider the circumstances of modern city dwellers in Los Angeles, Las Vegas, and even notoriously wet Seattle. Scott Stine and his fellow climatologists happen to know that the last century and a half, during which Californians have established what he calls "the most colossal urban and agricultural infrastructure in the entire world" (to which I might add "and all of history"), has been the third- or fourth-wettest period of that duration that California has enjoyed in the last four thousand years. Not unlike the Tiwanaku or the Anasazi, this modern society has taken advantage of a climatic optimum to construct its own sophisticated infrastructure and has placed itself, similarly, at the brink of its own environmental threshold. – Pages 180-181 |
I don't think I need to belabor the point that a prolonged drought will be drastic for America's westernmost states — no more than I need to emphasize the impact that loss of mountain glaciers will have, there and elsewhere around the world, in the long term.
But I will reiterate my refutation of denialists who continue to claim that glaciers aren't melting. The evidence to refute their denial is overwhelming. In addition to the measurements of increasing temperature and accelerating loss of ice from both poles and peaks mentioned in the sidebar, Bowen reports on pages 391-4 anecdotes from climbers testifying to the appearance of bare rock on their favorite routes.
The most shocking stories come from the greatest range of them all. I learned that Ama Dablam, a sublime white spire on the approach to Mount Everest that is often described as the most beautiful peak in the world, had been climbed without crampons recently. A glacier that was very close to the first camp used by Sir Edmund Hillary and Tenzing Norgay when they made the first ascent of Everest in 1953 has retreated about three miles since their success, and changes to the snow and ice farther up have greatly altered the scenes of some of the most legendary climbing sagas. Even the snow on the mountain's very summit has thinned enough to make it four feet shorter than it was in Hillary and Norgay's day. The Worldwatch Institute reports that the eastern Himalaya have lost one-fifth of their glaciers—two thousand in all—over the last century, and that the rate is accelerating. According to the Swiss-based International Commission on Snow and Ice, "Glaciers in the Himalayas are receding faster than in any other part of the world and, if the present rate continues, the likelihood of them disappearing by the year 2035 is very high." – Page 391 |
We also have dramatic photographs, taken decades apart, to show the retreat of glaciers in places like Glacier National Park. It all adds up to a crystal-clear picture that only fools will refuse to see.
To contact Chris Winter, send email to this address.