New “Ice Island” a Sign of Things to Come
Emergency Congressional Briefing Discusses Climate Change and Sea Level Rise
SOURCE: NASA
After breaking off the Petermann Glacier on August 5, 2010, a massive ice island floats slowly down the fjord toward the Nares Strait. The new ice island is roughly 251 square kilometers in size, four times larger than the island of Manhattan, and the largest new iceberg to form in the Northern Hemisphere in over 50 years.
Last week an island of ice four times the size of Manhattan broke free from Greenland’s Petermann Glacier and plunged into the ocean—yet another visible sign that the consequences of global warming are imminent and accelerating. In response, Rep. Edward Markey (D-MA) called an emergency science briefing session with the Select Committee on Energy Independence and Global Warming. Three scientists testified that the Arctic is warming and that they are deeply disturbed by what they see.
Glaciers such as those spread across Greenland hold almost 70 percent of the world’s freshwater. If all of the world’s glaciers were to melt, the sea level would rise approximately 230 feet. Although this extreme scenario is unlikely, the panel concluded that it would not be off base to link the latest ice island to embark into warmer waters with human-caused global warming.
This is the second major iceberg to break off, or calve, from glaciers this year, the first being the Merz Glacier Tongue in Antarctica in March. The new floating ice island is the largest iceberg in the northern hemisphere, and the freshwater contained in it is enough to supply the entire U.S. population with public tap water for 120 days, according to Dr. Andreas Muenchow, an associate professor of physical ocean science at the University of Delaware who testified before the subcommittee. Dr. Muenchow also noted in his testimony that the ice island was the largest piece to break from Greenland’s Petermann Glacier in 50 years.
If you have ever poured a cup of water over a glass of ice, you know how much more quickly the ice melts when it is in contact with water than when it sits in an empty cup. The same is true for glaciers. Once they break free from land and plop into the ocean, they can melt up to twice as fast, according to Dr. Rober Bindschadler, a senior research scientist at the University of Maryland, who also testified before the subcommittee. Land ice entering the sea and melting is the largest contributor to rising sea levels.
This event is consistent with scientists’ recent findings that sea level is expected to rise at least one meter (about three feet, three inches) by the end of the century due to global temperature increases but possibly by much more. These more recent projections far exceed the 0.6 feet-to-two-foot rise predicted by the Intergovernmental Panel on Climate Change. The scientists at the emergency briefing last week said the IPCC presented “underestimates.”
A 2008 study in the prestigious journal Nature Geoscience, for example, showed that glacial melt could cause the sea level to rise by as much as five feet by 2100. A more recent study in Nature showed that catastrophic sea level rise of 20 inches per decade for five straight decades occurred during the last interglacial period when the world was 2 degrees warmer. Since human-caused global warming is expected to cause an increase in temperature by at least 2 degrees this century, the authors conclude that such a drastic jump in sea levels could happen again:
“…the potential for sustained rapid ice loss and catastrophic sea-level rise in the near future is confirmed by our discovery of sea-level instability at the close of the last interglacial.”
“When the world warms, the Arctic warms more. When the Arctic warms more, Greenland melts,” explained Dr. Richard Alley, a professor of geosciences at Pennsylvania State University. In his testimony, he noted that both Greenland and the Arctic are losing mass.
Greenland’s ice sheet alone holds 10 percent of the world’s ice. If the whole of it were to melt, the scientists told the subcommittee that the global average sea level would rise 23 feet. Rep. Markey pointed out that water heights in New Orleans after Hurricane Katrina were almost this amount. Such sea level rise would drastically change the coastlines of each of the world’s continents, undoubtedly with severe social, economic, and security consequences.
Dr. Ally warned that it is possible that Greenland could completely melt by the end of this century. The scientists on the panel believe that a “tipping point” will be reached in one decade, where global temperatures become too high for Greenland’s ice sheet to remain frozen. Their claims are consistent with another study in Nature showing that the combined melting of Antarctic and Greenland coastal glaciers could create a “runaway effect” that would be difficult to reverse.
The panel of informed scientists that testified before the Select Subcommittee on Energy Independence and Global Warming agreed that this year’s melting in the polar regions is an early warning of future calamity. The scientists confirmed that this new ice island should be added to the snowballing narrative of global climate change.
Sean Pool is Special Assistant for energy, science, and technology policy at the Center for American Progress. Sarah Busch is a junior at Smith College and an intern at the Center for American Progress Energy Opportunity Team.
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