Climate Change 2007: The Physical Science Basis
Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change
Cambridge University Press, 996 pp., $90.00 (paper)
When the Rivers Run Dry: Water—The Defining Crisis of the Twenty-first Century
by Fred Pearce
Beacon, 324 pp., $16.00 (paper)
Too Smart for Our Own Good: The Ecological Predicament of Humankind
by Craig Dilworth
Cambridge University Press, 546 pp., $90.00; $29.99 (paper)
Black Soot and the Survival of Tibetan Glaciers
by Baiqing Xu, Junji Cao, James Hansen, and others
Proceedings of the National Academy of Sciences, December 29, 2009
On Avoiding Dangerous Anthropogenic Interference with the Climate System: Formidable Challenges Ahead
by Veerabhadran Ramanathan and Y. Feng
Proceedings of the National Academy of Sciences, September 23, 2008
The Great Melt: The Coming Transformation of the Arctic
by Alun Anderson
World Policy Journal, Winter 2009/2010
A full listing of sources appears at the end of this article.
It was not so long ago that the parts of the globe covered permanently with ice and snow, the Arctic, Antarctic, and Greater Himalayas (“the abode of the snows” in Sanskrit), were viewed as distant, frigid climes of little consequence. Only the most intrepid adventurers were drawn to such desolate regions as the Tibetan Plateau, which, when finally surveyed, proved to have the planet’s fourteen highest peaks. Because these mountains encompass the largest nonpolar ice mass in the world—embracing some 46,298 glaciers covering 17 percent of the area’s land and since time immemorial have held water in frozen reserve for the people of Asia—they have come to be known as “The Third Pole.”
There was a time when the immensity of such larger-than-life features of our natural world as oceans, deserts, mountains, and glaciers evoked awe and even fear. These days, however, these once seemingly eternal and invincible aspects of our planet’s architecture are on the defensive. And only belatedly are we beginning to understand how fragile and interconnected they actually are with myriad other elements of planetary life.
Through new scientific data, scholarly articles, books, NGO studies, and media reports, we now know that the melting of polar ice will lead to rising ocean levels and the inundation of many heavily populated areas in vulnerable lowland countries. But we are only beginning to become acquainted with the less-well-known consequences that are starting to flow out of the majestic arc of mountains that begins in Inner Asia with the Tianshan Range in western China and then wraps itself around the western tier of the Tibetan Plateau as it becomes the Hindu Kush in northern Afghanistan. It then joins the Karakorum in northern Pakistan to become the Himalayas above Nepal, Bhutan, and India before ending with the Hengduan Range in southwest China. (See map on page 48.)
Scientists are now warning that there could be a 43 percent decrease in land mass covered with ice in these mountains by 2070 and that in numerous and complex ways this loss will affect Asia’s ten major rivers—the Yellow, Yangtze, Mekong, Salween, Irrawaddy, Brahmaputra, Ganges, Indus, Amu Darya, and Tarim—around which many of the ancient civilizations of the world arose. It is here, among huge modern-day populations of Asia, that the melting of the Greater Himalayas’ glaciers will have the most significant impact during the coming decades and centuries.
Recent revelations that the Fourth Assessment Report of the UN’s Intergovernmental Panel on Climate Change (IPCC) erroneously claimed that there was a “likelihood” that Himalayan glaciers would disappear by 2035, “and perhaps sooner,” embarrassed the report’s authors; but they have not altered the reality that many glaciers in the region are, in fact, rapidly receding. Nor do they scientifically invalidate the panel’s overall conclusion that because “more than one-sixth of the world’s population live in glacier- or snowmelt-fed river basins and will be affected by the seasonal shifts in stream flow,” a serious downstream problem is unfolding.
Glacial ice-melt from the Greater Himalayas provides Asian river systems with important seasonal flows of water. A 2005 World Wildlife Fund report observes that in Nepal, India, and China, “glacial melt will affect freshwater flows with dramatic adverse effects on biodiversity, and people and livelihoods, with a possible long-term implication on regional food security.”
The Indus and Tarim rivers, for example, derive up to 50 percent of their annual flows from glacial melt. The Yangtze derives 18 percent, while the Salween derives 9 percent from such meltwaters. But what makes glacial melt so critical, even when it is a relatively small percentage of a river’s annual flow, is the timing at which it occurs. If these flows come during the rainy monsoon season, they may lead to floods. But if they come during the hot, dry spring and fall months, the so-called “shoulder seasons” just before and after the monsoon, they keep the volumes of river water more constant and are welcomed. For such rivers as the Ganges, Indus, and Kabul, meltwaters can account for as much as 70 percent of spring and fall flows.
As the science writer Fred Pearce puts it in When the Rivers Run Dry, by storing monsoon rain as snow and ice when it is not needed, and then releasing it slowly as water when it is, glaciers “provide a strong, regular flood pulse in the summer melting season.” Any disruption in these flows—especially when a monsoon is late, weak, or fails—significantly disturbs not only agriculture but industry, fisheries, transportation, and many other aspects of life for hundreds of millions of people downstream. That is the case this year in drought-stricken southwest China through which the Yangtze, Mekong, and Irrawaddy all flow.
Until now, the formidable glaciers of the world hardly seemed vulnerable. While they may appear immobile, they are actually “rivers of ice,” as the great Swiss geologist Louis Agassiz described them, and are constantly moving downward from their “accumulation zones” high on mountainsides where snows fall and are compressed into “firn,” the blue ice that gives glaciers their air of frozen purity. Pushed by their own immense weight, and aided by meltwaters, which seep down crevasses to lubricate the interface between ice and rock, glaciers make their slow gravity-driven progress downward, carving out whole valleys as they move and gathering up so much debris before them and on their surfaces that they often look more like conveyor belts for rocks than icefalls.
A glacier’s lower reaches are known as its “ablation zone,” because it is here that it “calves,” or sloughs off, giant pieces of itself in a process that can give off unearthly noises—like a giant door creaking open or even a cannon shot. After these terrestrial icebergs break off, the ice begins the final stage of its long odyssey to the sea, as meltwaters flow into the river systems of the vast and populous Asian continent.
As long as the buildup of new ice in a glacier’s accumulation zone remains greater than losses in its ablation zone, “mass balance,” or equilibrium, is maintained. But most of the world’s “reference glaciers”—those two hundred–plus that have been under observation over the past sixty years by the Switzerland-based UN World Glacier Monitoring Service—have begun to record significant losses.
Only now, as these glaciers have been put in jeopardy by man’s voracious appetite for energy, are we starting to become more aware of the critical links between the thirsty, riverine lowland population centers of East, Southeast, and South Asia and the high-altitude ice fields of the Greater Himalayas. And it has been climate change that has drawn our attention to the connection.
The amount of heat-trapping greenhouse gases (GHGs) emitted annually is now roughly twice what the earth can recycle through natural processes of reabsorption. By interfering with the planet’s ability to reflect incoming solar heat from the earth’s atmosphere, over the past century these gases have caused an average rise in global temperature of three quarters of a degree centigrade (0.74°C). But scientists who construct models of global warming to predict future outcomes also believe that because of an ongoing delayed reaction, existing GHG emissions (those released before 2005) alone—quite aside from future emissions—will, during the next century, cause an additional threefold temperature rise, of approximately 2.4°C. Furthermore, they contend, unless current emissions rates are radically curbed, it is even possible that future average temperatures could rise by as much as 4.3°C.
A few degrees here and there may not seem like much to a layman; but ecosystems, especially those involving ice, are so delicately balanced that even shifts of a degree or two have profound impacts, as we are now beginning to discern.
One of the most respected, pioneering scientists concerned with global warming is Veerabhadran Ramanathan at the University of California–San Diego’s Scripps Institution of Oceanography. He and his colleague Y. Feng point out that these estimated aggregate temperature rises surpass “the currently perceived threshold range of 1°C to 3°C for dangerous anthropogenic interference with many of the climate-tipping elements such as the summer arctic sea ice, Himalayan-Tibetan glaciers, and the Greenland Ice Sheet.” In other words, we are close to passing a tipping point—one that many scientists formerly put much lower, at an increase of 1.5–2.0°C—and are entering a danger zone where ice systems on the planet will be put even more irrevocably in peril.
What is more, when it comes to the Greater Himalayan region, climatologists tell us that global temperature averages are a very deceptive measure. For reasons that scientists are just beginning to understand, far greater temperature rises occur as a result of global warming in certain high-altitude regions than elsewhere. On the Tibetan Plateau, warming has increased at upward of three times the global average.
Two of the world’s leading glaciologists, Lonnie Thompson, distinguished university professor at Ohio State University’s Byrd Polar Research Center, and Yao Tandong, director of the Chinese Academy of Sciences’ Institute of Tibetan Plateau Research, both of whom have worked extensively in the Himalayas studying oxygen isotopes in glacial ice cores, have concluded that temperatures in these mountains are likely to rise as much as 5–6°C over the next one hundred years. Needless to say, such precipitous rises would only accelerate melting and lead to an even more drastic loss in ice mass, as well as an increase in a potentially catastrophic series of outbursts of water from glacial lakes, downriver flooding, and then, eventually, to diminished flows and periods of drought, affecting human communities both upstream and down. As Zheng Guoguang, head of the China Meteorological Bureau, recently put it, “If the warming continues, millions of people in western China will face floods in the short term and drought in the long run.”
“The current warming at high elevations in the mid- to low latitudes is unprecedented for at least the last 2 millennia,” writes Thompson in the Proceedings of the National Academy of Sciences. “The continuing retreat of most mid- to low-latitude glaciers, many having persisted for thousands of years, signals a recent and abrupt change in the Earth’s climate system.” This change, he writes, “may signal that the climate system has exceeded a critical threshold and that most low-latitude, high-altitude glaciers are likely to disappear in the near future.”
As important as rising temperatures are in understanding what is happening to Tibetan Plateau glaciers, another major factor is also causing damage: black carbon.
Atmospheric brown clouds, or ABCs, are aerosol suspensions of very small particles created by the inefficient combustion of coal, kerosene, and diesel oil, as well as biofuels from home cooking fires. In India, emissions from these sources increased sixfold between 1930 and 2000 and this particulate matter now causes the brown clouds that regularly hang like a pall over densely populated areas of the Indian subcontinent and China.
ABCs are made up of a variety of particles that have the capacity to both absorb and reflect solar heat. Since dust and black carbon soot particles absorb heat, they increase global warming. (Ramanathan and Feng estimate that such absorption causes as much as 50 percent of the warming of the atmosphere.) But ABCs also decrease warming, because they contain sulfate and nitrate particles, which act like little mirrors reflecting incoming heat back out of the atmosphere, resulting in lower temperatures at ground level. Ramanathan and Feng believe that this “dimming” or “surface cooling effect” has “masked a significant fraction of the warming effect of the GHGs blanket.”
At first, one might feel relieved to learn this rather counterintuitive fact. But as scientists go on to point out, because heat-reflecting particles in ABCs are very short-lived in the atmosphere (falling back to earth after emission in a matter of weeks), while the GHGs from the burning of these fuels last in the atmosphere for decades, the gain is only temporary. What is more, if mankind does find a way to clean up these toxic clouds, these scientists say it would be “like removing the mask.” Very quickly thereafter, because their “dimming effect” would be lost, “the climate may play catch-up to compensate,” causing the planet to experience a rapid leap of approximately 1.6°C in additional warming. In other words, as serious as the planet’s already warmed state is, should ABCs ever be eliminated we will be in for a significant, unexpected, and unwelcome further jump in temperature.
Of course, none of these sources of additional warming are good news for glaciers. But the most immediately harmful effect on Himalayan ice from ABCs comes from yet something else: the black carbon soot that migrates up onto the Tibetan Plateau, carried by precipitating monsoons.
When we think of glaciers, we usually evoke images of pristine, white leviathans of mountain ice, radiant in the sunlight, sweeping down spectacular alpine valleys to produce streams of cold, pure water. When we think of fossil fuels, on the other hand, we imagine very different images—of dark, grimy coal mines and pitch-black oil gushers and spills that despoil nature. While at first blush glaciers and fossil fuels may seem opposite and unrelated, in reality they are intimately connected, and one important link is black carbon soot.
James Hansen, director of NASA’s Goddard Institute of Space Studies, and Chinese glaciologist Yao Tandong have been doing research and fieldwork on how the black carbon that was once immobilized deep beneath the ground now affects the snowy surfaces of high-altitude glaciers and will become “a significant contributing factor to observed rapid glacier retreat.” While airborne ABCs can migrate across oceans, making one country’s pollutants another’s problem, black carbon from India is more immediately deposited on Himalayan glaciers via warm, moisture-laden, southerly monsoon winds that sweep it up onto the Tibetan Plateau. When cooled at high altitudes, this moist monsoon air condenses into rain and snow. However, because of increasingly warmer high-altitude temperatures, once the soot-laden snow lands, more of it now quickly melts before new snow can bury it and compress it into glacial ice. So with successive meltings of new layers of freshly fallen snow, concentrations of black soot build up, turning the surface of glaciers into giant collectors of solar heat.
On the accumulation zone of one glacier in the Qilian Mountains in western China, Hansen and Yao found that “fresh snow melted within two days, exposing dirtier underlying snow with black carbon concentration seven times greater than the fresh snow.” They concluded that the soot burden, which had markedly increased since 1990, had now become “sufficient to affect the surface reflectivity of the glaciers,” by increasing their “effectiveness in absorbing sunlight.” With their natural reflective and self-protective ability, or “albedo,” impaired by soot, and with temperatures continuing to rise, scientists like Hansen and Yao now fear that “most glaciers, worldwide, will be lost this century, with severe consequences for fresh water supplies.”
On a trip I made recently to the Tibetan Plateau in Yunnan province to observe the Yongming and the Baishui #1 glaciers, what was striking was just how gritty both their surfaces were. This is not unusual, but here it was a reminder that the wages of soot, along with warming, are speeding these two glaciers on their way to being among the fastest melting in the Greater Himalayas. It is hardly surprising, then, that while between 1950 and 1980 only 50 percent of the glaciers in the Tibetan region were in a state of recession, during the early part of this century that figure rose to 95 percent.
The Permafrost Melt
As global temperatures continue to rise, moreover, the vast expanse of permafrost beneath much of the grasslands on the Tibetan Plateau’s northern tier is also now at risk of thawing. This will have effects on the watershed that feeds the Yellow and other rivers. It will also accelerate desertification and degrade the pasturelands on which traditional nomads have long depended. But the most profound global impact of this thawing, which has already begun, will be the enormous amounts of methane gas—roughly twenty times more potent in heat-trapping capacity than CO2—that will be released by the decomposition of once-frozen carbon rich organic matter in the area’s soil. Indeed, continued thawing threatens to turn what has been a major carbon-sink—sequestering about 2.5 percent of the world’s soil carbon—into a huge new source of emissions.
Ice in the Rest of the World
The Greater Himalayas are, of course, not the only place in the world where ice is melting. According to the World Glacier Monitoring Service, average annual glacier global melt rates “appear to have doubled after the turn of the millennium, in comparison with the already accelerated melting rates observed in the two decades before.”
The ice on Mount Kilimanjaro, which a century ago was twelve square kilometers in size, has now been reduced to less than 1.5 square kilometers, and is predicted to be completely gone within two decades. In Montana’s Glacier National Park, the spring season—as measured by temperature—now starts forty-five days earlier than when the park was established in 1910. Then, the park had 150 glaciers, whereas now only twenty-five remain, and park staff predicts that even these will be gone by 2030. And most of the Rhône Glacier in the Swiss Alps, a major water source for Europe’s Rhone River, is now expected to be gone by the end of the century.
Global warming is also having serious effects on Arctic and Antarctic ice systems. Summer Arctic ice has shrunk from 7.5 million square kilometers in the late 1970s to 4.5 million square kilometers in 2007. As Alun Anderson, author of After the Ice, put it in a recent article, “The Great Melt”:
For millions of years, the great dome of brilliant white ice at the top of the planet has reflected the 24-hour polar summer sunlight back into space, helping cool the entire globe…. We are almost certainly too late to reverse the disappearance of Arctic ice—even if drastic cuts are made in greenhouse gas emissions.
Another large concern is that melting glaciers on the Tibetan Plateau, and other climate change–induced disruptions, will have “cascading effects” across ecosystems, creating chain reactions of disturbed relations between ice, water, plants, animals, and people in a complex web of cause and effect that scientists have hardly begun to probe.
Is it possible to keep the delicate ecology of these crucial Asian mountains from being pushed further out of balance in ways that will ripple out through the larger environment and downward through some of the most populous places in the world? Only if we find a way to reduce GHG emissions and carbon soot levels in the atmosphere.
Such reductions would require not only new transnational strategies, but new regional organizations. Countries like India and China have at last begun to discuss the issue of glaciers, and an awareness of the consequences of climate change has been advancing rapidly in both countries. But the Indian minister of environment and forests, Jairam Ramesh, recently released a report questioning whether glaciers in the region are actually melting in a precipitous manner, and the two countries have yet to take joint action. Yet this is not a national but an international problem. And since UN-sponsored international discussions on climate change ended in a stalemate at Copenhagen in December 2009, only isolated responses—some impressive in their ingenuity, but ineffective in terms of any grand solution—have actually been undertaken.
An enterprising road-builder from Ladakh in northern India, Chewang Norphel, launched an unusual effort in response to a retreating glacier in northern India that farmers had relied on for centuries to irrigate their spring planting. The glacier had retreated to such a high altitude that the meltwaters, which had traditionally begun to flow in March, did not start until May (when it is too late to plant and still harvest before winter). Noticing that there was water gushing from a pipe left open during the winter to keep it from freezing, Norphel began using the water to flood a small field, in effect slowly creating, as it froze, a small artificial glacier that could be counted on to melt in March when it was needed.
“People laughed when I first presented the idea,” he told Science. But when spring came and these same people saw water flowing to their fields, they started helping. Ultimately, his artificial glacier grew to be two kilometers long and Norphel, now known as “Glacier Man,” went on to create nine other such synthetic glaciers.
Norphel’s ingenious project got attention in the press. But it did little to remedy the larger challenge: that the lives of hundreds of millions of people across Asia are going to be affected because of what is happening in the remoteness of the Tibetan Plateau.
Not long ago it would have seemed extreme for respected scientists to warn so overtly of environmental apocalypse. But now we quite regularly hear the likes of NASA’s James Hansen warn that “continued ‘business-as-usual’ emission of greenhouse gases and black soot will result in the loss of most Himalayan glaciers this century, with devastating effects on fresh water supplies.”
Or we hear Chinese scientists, like glaciologist Yao Tandong, bluntly cautioning that “studies indicate that by 2030 another 30 percent [of the Himalayan glaciers] will disappear; by 2050, 40 percent; and by the end of the century 70 percent,” and that “the full-scale glacier shrinkage in the plateau regions will eventually lead to an ecological catastrophe.” Moreover, scores of reports are now pouring out of NGOs, also sounding alarms.
“This mountain system [the Himalayas] is extremely vulnerable to global warming,” warns a recent report from the Kathmandu-based International Centre for Integrated Mountain Development. “Uncertainties about the rate and magnitude of climate change and potential impacts prevail, but there is no question that [climate change] is gradually and powerfully changing the ecological and socioeconomic landscape…. Business as usual is not an option.”
Still, even as the scientific evidence of human impact on this defiant but delicate region piles up around us and we see the patrimony of these glaciers melt away before our eyes, we remain strangely reluctant to acknowledge how radically we have altered our relationship to this part of the natural world. Why, wonders Craig Dilworth in his invigoratingly pessimistic new book, Too Smart for Our Own Good: The Ecological Predicament of Humankind, do we make “no serious attempt to remedy the situation, despite our being aware of it?”
There are, of course, many answers. But surely it is one of the great ironies of our age that even in the midst of the “Information Technology Revolution,” which daily inundates us with vast quantities of information that are supposed to inform and liberate us, we are still unable to synthesize it so as to galvanize ourselves for action.
There are many links in the chain of cause and effect that stretches from the melting glaciers of the Greater Himalayas to the Indian or Chinese peasant who relies on the waters of the Ganges or the Yellow River to survive. And many more studies should be undertaken to scientifically clarify all these links. But there is already enough information for the world to know that we confront a very dangerous prospect, with no adequate effort underway to find the missing link between the knowledge we already have and action.
—Beijing, April 26, 2010
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'The Message from the Glaciers' July 15, 2010