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Chapter 3. Rising Temperatures and Rising Seas: Melting Ice and Rising Seas
Ice melting in mountainous regions not only affects river flows, it also affects sea level rise. On a larger scale, the melting of the earth’s two massive ice sheets—Antarctica and Greenland—could raise sea level enormously. If the Greenland ice sheet were to melt, it would raise sea level 7 meters (23 feet). Melting of the West Antarctic Ice Sheet would raise sea level 5 meters (16 feet). But even just partial melting of these ice sheets will have a dramatic effect on sea level rise. Senior scientists are noting that the IPCC projections of sea level rise during this century of 18 to 59 centimeters are already obsolete and that a rise of 2 meters during this time is within range. 35
Assessing the prospects for the Greenland ice sheet begins with looking at the warming of the Arctic region. A 2005 study, Impacts of a Warming Arctic, concluded that the Arctic is warming almost twice as fast as the rest of the planet. Conducted by the Arctic Climate Impact Assessment (ACIA) team, an international group of 300 scientists, the study found that in the regions surrounding the Arctic, including Alaska, western Canada, and eastern Russia, winter temperatures have already climbed by 3-4 degrees Celsius (4–7 degrees Fahrenheit) over the last half-century. Robert Corell, chair of ACIA, says this region “is experiencing some of the most rapid and severe climate change on Earth.” 36
In testimony before the U.S. Senate Commerce Committee, Sheila Watt-Cloutier, an Inuit speaking on behalf of the 155,000 Inuits who live in Alaska, Canada, Greenland, and the Russian Federation, described their struggle to survive in the fast-changing Arctic climate as “a snapshot of what is happening to the planet.” She called the warming of the Arctic “a defining event in the history of this planet.” And she went on to say “the Earth is literally melting.” 37
The ACIA report described how the retreat of the sea ice has devastating consequences for polar bears, whose very survival may be at stake. A subsequent report indicated that polar bears, struggling to survive, are turning to cannibalism. Also threatened are ice-dwelling seals, a basic food source for the Inuit. 38
Since this 2005 report, there is new evidence that the problem is worse than previously thought. A team of scientists from the National Snow and Ice Data Center and the National Center for Atmospheric Research, which has compiled data on Arctic Ocean summer ice melting from 1953 to 2006, concluded that the ice is melting much faster than climate models had predicted. They found that from 1979 to 2006 the summer sea ice shrinkage accelerated to 9.1 percent a decade. In 2007, Arctic sea ice shrank some 20 percent below the previous record set in 2005. This suggests that the sea could be ice-free well before 2050, the earliest date projected by the IPCC in its 2007 report. Arctic scientist Julienne Stroeve observed that the shrinking Arctic sea ice may have reached “a tipping point that could trigger a cascade of climate change reaching into Earth’s temperate regions.” 39
Reinforcing this concern is a recent study by Joséfino Comiso, a senior scientist at NASA’s Goddard Space Flight Center. Comiso reported for the first time that even the winter ice cover in the Arctic Ocean shrank by 6 percent in 2005 and again in 2006. This new development, combined with the news that the sea ice cover is thinning, provides further evidence that the ice is not recovering after its melt season, meaning that summer ice in the Arctic Ocean could disappear much sooner than earlier thought possible. 40
Walt Meier, a researcher at the U.S. National Snow and Ice Data Center who tracks the changes in Arctic sea ice, views the winter shrinkage with alarm. He believes there is “a good chance” that the Arctic tipping point has been reached. “People have tried to think of ways we could get back to where we were. We keep going further and further in the hole, and it’s getting harder and harder to get out of it.” Some scientists now think that the Arctic Ocean could be ice-free in the summer as early as 2030. 41
Scientists are concerned that “positive feedback loops” may be starting to kick in. This term refers to a situation where a trend already under way begins to reinforce itself. Two of these potential feedback mechanisms are of particular concern to scientists. The first, in the Arctic, is the albedo effect. When incoming sunlight strikes the ice in the Arctic Ocean, up to 70 percent of it is reflected back into space. Only 30 percent is absorbed as heat. As the Arctic sea ice melts, however, and the incoming sunlight hits the much darker open water, only 6 percent is reflected back into space and 94 percent is converted into heat. This may account for the accelerating shrinkage of the Arctic sea ice and the rising regional temperature that directly affects the Greenland ice sheet. 42
If all the ice in the Arctic Ocean melts, it will not affect sea level because the ice is already in the water. But it will lead to a much warmer Arctic region as more of the incoming sunlight is absorbed as heat. This is of particular concern because Greenland lies largely within the Arctic Circle. As the Arctic region warms, the island’s ice sheet—up to 1.6 kilometers (1 mile) thick in places—is beginning to melt. 43
The second positive feedback mechanism also has to do with ice melting. What scientists once thought was a fairly simple linear process—that is, a certain amount at the surface of an ice sheet melts each year, depending on the temperature—is now seen to be much more complicated. As the surface ice begins to melt, some of the water filters down through cracks in the glacier, lubricating the surface between the glacier and the rock beneath it. This accelerates the glacial flow and the calving of icebergs into the surrounding ocean. The relatively warm water flowing through the glacier also carries surface heat deep inside the ice sheet far faster than it would otherwise penetrate by simple conduction. 44
Several recent studies report that the melting of the Greenland ice sheet is accelerating. A study published in Science in September 2006 reported that the rate of ice melt on the vast island has tripled over the last several years. That same month a University of Colorado team published a study in Nature indicating that between April 2004 and April 2006 Greenland lost ice at a rate 2.5 times that of the preceding two years. In October 2006, a team of NASA scientists reported that the flow of glaciers into the sea was accelerating. Eric Rignot, a glaciologist at NASA’s Jet Propulsion Laboratory, said, “None of this has been predicted by numerical models, and therefore all projections of the contribution of Greenland to sea level [rise] are way below reality.” 45
At the other end of the earth, the 2-kilometer-thick Antarctic ice sheet, which covers a continent about twice the size of Australia and contains 70 percent of the world’s fresh water, is also beginning to melt. Ice shelves that extend from the continent into the surrounding seas are starting to break up at an alarming pace. 46
In May 2007, a team of scientists from NASA and the University of Colorado reported satellite data showing widespread snow-melt on the interior of the Antarctic ice sheet over an area the size of California. This melting in 2005 was 900 kilometers inland, only about 500 kilometers from the South Pole. Konrad Steffen, one of the scientists involved, observed, “Antarctica has shown little to no warming in the recent past with the exception of the Antarctic Peninsula, but now large regions are showing the first signs of the impacts of warming.” 47
The ice shelves surrounding Antarctica are formed by the flow of glaciers off the continent into the surrounding sea. This flow of ice, fed by the continuous formation of new ice on land and culminating in the breakup of the shelves on the outer fringe and the calving of icebergs, is not new. What is new is the pace of this process. When Larsen A, a huge ice shelf on the east coast of the Antarctic Peninsula, broke up in 1995, it was a signal that all was not well in the region. Then in 2000, a huge iceberg nearly the size of Connecticut—11,000 square kilometers, or 4,250 square miles—broke off the Ross Ice Shelf. 48
After Larsen A broke up, it was only a matter of time, given the rise in temperature in the region, before neighboring Larsen B would do the same. So when the northern part of the Larsen B ice shelf collapsed into the sea in March 2002, it was not a total surprise. At about the same time, a huge chunk of ice broke off the Thwaites Glacier. Covering 5,500 square kilometers, this iceberg was the size of Rhode Island. 49
Even veteran ice watchers are amazed at how quickly the disintegration is occurring. “The speed of it is staggering,” said Dr. David Vaughan, a glaciologist at the British Antarctic Survey, which has been monitoring the Larsen Ice Shelf closely. Along the Antarctic Peninsula, in the vicinity of the Larsen Ice Shelf, the average temperature has risen 2.5 degrees Celsius over the last five decades. 50
When ice shelves already largely in the water break off from the continental ice mass, this does not have much direct effect on sea level per se. But without the ice shelves to impede the flow of glacial ice, typically moving 400–900 meters a year, the flow of ice from the continent could accelerate, leading to a thinning of the ice sheet on the edges of the Antarctic continent. If this were to happen, sea level would rise accordingly. 51
The International Institute for Environment and Development (IIED) has analyzed the effect of a 10-meter rise in sea level, providing a sense of what the melting of the world’s largest ice sheets could mean. The IIED study begins by pointing out that 634 million people live along coasts at or below 10 meters above sea level, in what they call the Low Elevation Coastal Zone. This massive vulnerable group includes one eighth of the world’s urban population. 52
One of the countries most vulnerable is China, with 144 million potential climate refugees. India and Bangladesh are next, with 63 and 62 million respectively. Viet Nam has 43 million vulnerable people, and Indonesia, 42 million. Others in the top 10 include Japan with 30 million, Egypt with 26 million, and the United States with 23 million. 53
The world has never seen such a massive potential displacement of people. Some of the refugees could simply retreat to higher ground within their own country. Others—facing extreme crowding in the interior regions of their homeland—would seek refuge elsewhere. Bangladesh, already one of the world’s most densely populated countries, would face a far greater concentration: in effect, 62 million of its people would be forced to move in with the 97 million living on higher ground. Would a more sparsely populated country like the United States be willing to accommodate an influx of rising-sea refugees while it was attempting to relocate 23 million of its own citizens? 54
Not only would some of the world’s largest cities, such as Shanghai, Kolkata, London, and New York, be partly or entirely inundated, but vast areas of productive farmland would also be lost. The rice-growing river deltas and floodplains of Asia would be covered with salt water, depriving Asia of part of its food supply. This loss of prime farmland would parallel the loss of river water as Himalayan glaciers disappear. 55
In the end, the question is whether governments are strong enough to withstand the political and economic stress of relocating large numbers of people while suffering losses of housing and industrial facilities. The relocation is not only an internal matter, as a large share of the displaced people will want to move to other countries. Can governments withstand these stresses, or will more and more states fail?
35. UNEP, op. cit. note 1, p. 103; IPCC, Summary for Policymakers, op. cit. note 9, p. 13; Paul Brown, “Melting Ice Cap Triggering Earthquakes,” Guardian (London), 8 September 2007.
36. Arctic Climate Impact Assessment (ACIA), Impacts of a Warming Arctic (Cambridge, U.K.: Cambridge University Press, 2004); ACIA Web site, at www.acia.uaf.edu, updated 13 July 2005; “Rapid Arctic Warming Brings Sea Level Rise, Extinctions,” Environment News Service, 8 November 2004; UNEP, op. cit. note 1, p. 103.
37. J. R. Pegg, “The Earth is Melting, Arctic Native Leader Warns,” Environment News Service, 16 September 2004.
38. ACIA, op. cit. note 36; Steven Armstrup et al., “Recent Observations of Intraspecific Predation and Cannibalism among Polar Bears in the Southern Beaufort Sea,” Polar Biology, vol. 29, no. 11 (October 2006), pp. 997–1002.
39. Julienne Stroeve et al., “Arctic Sea Ice Decline: Faster than Forecast,” Geophysical Research Letters, vol. 34 (May 2007); National Snow and Ice Data Center (NSIDC), “Arctic Sea Ice Shatters all Previous Record Lows,” press release (Boulder, CO: 1 October 2007); Stroeve quoted in “Arctic Ice Retreating 30 Years Ahead of Projections,” Environment News Service, 30 April 2007.
40. Marc Kaufman, “Decline in Winter Arctic Ice Linked to Greenhouse Gases,” Washington Post, 14 September 2006; Joséfino C. Comiso, “Abrupt Decline in the Arctic Winter Sea Ice Cover,” Geophysical Research Letters, vol. 33, 30 September 2006.
41. David Adam, “Meltdown Fear as Arctic Ice Cover Falls to Record Winter Low,” Guardian ( London), 15 May 2006.
42. NSIDC, “Processes: Thermodynamics: Albedo,” at nsidc.org/seaice/ processes/albedo.html, viewed 26 July 2007.
43. UNEP, op. cit. note 1.
44. H. Jay Zwally et al., “Surface Melt-Induced Acceleration of Greenland Ice-Sheet Flow,” Science, vol. 297 (12 July 2002), pp. 218–22.
45. J. L. Chen, C. R. Wilson, and B. D. Tapley, “Satellite Gravity Measurements Confirm Accelerated Melting of Greenland Ice Sheet,” Science, vol. 313 (29 September 2006), pp. 1958–60; Isabella Velicogna and John Wahr, “Acceleration of Greenland Ice Mass Loss in Spring 2004,” Nature, vol. 443 (21 September 2006), pp. 329–31; S. B. Luthke et al., “Recent Greenland Ice Mass Loss from Drainage System from Satellite Gravity Observations,” Science, vol. 314 (24 November 2006), pp. 1286-89; “Gravity Measurements Confirm Greenland’s Glaciers Precipitous Meltdown,” Scientific American, 19 October 2006.
46. U.S. Department of Energy, Energy Information Administration, “ Antarctica: Fact Sheet,” at www.eia.doe.gov, September 2000.
47. University of Colorado at Boulder, “NASA, CU-Boulder Study Shows Vast Regions of West Antarctica Melted in Recent Past,” press release ( Boulder: 15 May 2007).
48. “Breakaway Bergs Disrupt Antarctic Ecosystem,” Environment News Service, 9 May 2002; “Giant Antarctic Ice Shelves Shatter and Break Away,” Environment News Service, 19 March 2002.
49. NSIDC, “Antarctic Ice Shelf Collapses,” at nsidc.org/iceshelves/ larsenb2002, 19 March 2002; “Breakaway Bergs Disrupt Antarctic Ecosystem,” op. cit. note 48; “Giant Antarctic Ice Shelves Shatter and Break Away,” op. cit. note 48.
50. “Giant Antarctic Ice Shelves Shatter and Break Away,” op. cit. note 48; Vaughan quoted in Andrew Revkin, “Large Ice Shelf in Antarctica Disintegrates at Great Speed,” New York Times, 20 March 2002.
51. Michael Byrnes, “New Antarctic Iceberg Split No Threat,” Reuters, 20 May 2002.
52. Gordon McGranahan et al., “The Rising Tide: Assessing the Risks of Climate Change and Human Settlements in Low Elevation Coastal Zones,” Environment and Urbanization, vol. 18, no. 1 (April 2007), pp. 17–37.
54. Ibid.; U.N. Population Division, op. cit. note 20.
55. International Institute for Environment and Development, “Climate Change: Study Maps Those at Greatest Risk from Cyclones and Rising Seas,” press release ( London: 28 March 2007); Catherine Brahic, “Coastal Living–A Growing Global Threat,” New Scientist.com, 28 March 2007; UNEP, op. cit. note 1.
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