Repercussions of a Melting Planet
|The southern tip of Greenland.|
Ice in the Arctic region is disappearing—and quickly. Scientists from the University of Colorado’s National Snow and Ice Data Center (NSIDC) report that this year’s retreat of Arctic sea ice could be the most extreme since monitoring of the polar ice cap began in 1979. The loss of permanent sea ice is “the most irrefutable evidence” that global warming is affecting the environment, says Ted Scambos, lead scientist with NSIDC.
In 2005—the warmest year ever recorded, according to scientists—the summer extent of Arctic sea ice hit a record low, covering an area 20 percent less than the average minimum of 7 million square kilometers between 1979 and 2000. The 2006 retreat, which peaks in September, is expected to be even greater. By the end of July, Arctic sea ice covered only 8.7 million square kilometers, down from 9.1 million in 2005 and 10.1 million on average for the 1979–2000 period. Wieslaw Maslowski, professor of oceanography at the Naval Postgraduate School in Monterrey, California, has warned that summer sea ice could disappear completely by 2020. More conservative estimates by NSIDC put the date at 2050.
Recent satellite data shows that melting of Greenland’s massive land-based ice sheet has accelerated as well. Measurements from NASA’s Gravity Recovery and Climate Experiment satellite suggest that some 239 cubic kilometers of ice is being lost per year, almost a three fold increase in melting from the 2002 to 2004 average. At least part of this measured increase, however, may be attributed to better data processing in recent years, according to Jianli Chen with the University of Texas at Austin.
Unlike melting sea ice, which floats on the surface of the water, loss of land-based ice could lead to rising sea levels with catastrophic effects, including greater risks from severe storm surges and permanent submergence of low-lying areas. At today’s estimated melt rate, the accelerated mass loss from Greenland’s ice sheet alone would raise sea level by an additional half a millimeter per year. (Currently, thermal expansion and the addition of about 20 billion tons of water increases sea levels approximately 3 millimeters per year.) Donald F. Boesch, with the University of Maryland’s Center for Environmental Sciences, estimates that each millimeter increase in sea level results in shoreline retreats of approximately 1.5 meters; if Greenland’s ice sheet were to melt completely, global sea levels would rise 6.5 meters.
Several countries have long been at risk of being overrun by rising tides. In October 1987, the president of the Maldives, a group of 1,196 islands near the southern tip of India, gave an impassioned address at the United Nations warning that his nation of 311,000 people was endangered. Even a one-meter rise in sea level would be catastrophic to the Maldives as storm surges batter the islands, most of which are less than two meters above sea level.
The low-lying island nation of Tuvalu, midway between Hawaii and Australia, has already conceded defeat to rising sea levels and is pursuing plans to evacuate. Tuvaluans will likely be among the first to see their country swallowed by the ocean should sea levels continue to rise: the country’s highest point is just five meters high, with much of the land well below that. During certain periods of the year, tides already rise 1.5 meters above sea level. New Zealand has upped its immigration quota to 75 Tuvaluans per year as part of a labor entry program, and has, after considerable negotiation, agreed to accept the nation’s 11,600 refugees if and when the island is submerged.
Experts with the United Nations University predict that rising sea levels and environmental deterioration will displace as many as 50 million people by 2010. Yet according to John Young, former senior researcher at the Worldwatch Institute, the greatest cost of rising sea levels will not be the loss of land but the inevitable disruption of communities and cultures that cannot be replicated elsewhere.
This story was produced by Eye on Earth, a joint project of the Worldwatch Institute and the blue moon fund. View the complete archive of Eye on Earth stories, or contact Staff Writer Alana Herro at aherro [AT] worldwatch [DOT] org with your questions, comments, and story ideas.