LNW_2007Arctic.IceMelt

Does a global sea-level rise of 10 to 20 feet sound to you like a matter of national security?

Scientists are stunned at the unprecedented speed at which the Arctic ice cap is melting, and fear it may all be gone by 2030, The Guardian (UK) reports. In 2007 the ice melted 24 percent more than it did in 2005. An area almost twice the size of Great Britain disappeared in a single week in September. (The Washington Post’s Oct. 22 report—buried inside on page A10—appears here.)

The Arctic ice cap normally melts to some extent every summer, but it’s been melting at alarming rates in recent years. The sea ice extends only about half as far as it did 50 years ago, and the Arctic has lost about one-third of its area since satellite measurements began about the mid-1970s.

Every year, more and more of the melted ice is staying as water. That causes some sea-level rise. The white of the ice caps reflects great amounts of sunlight back out of the atmosphere, while dark seawater has about 1/10 the reflectivity, and so absorbs more heat. Heat makes water expand, further raising the sea level. Further, as the permafrost melts, methane and other long-frozen gases are released, adding to the greenhouse effect. Estimates vary, but considering the speed at which the ice caps are melting, some scientists foresee sea-level rises of more than 10 feet, possibly over 20, in the next century. The last time the earth’s surface temperature was at its present warmth—3 million years ago—the sea level was about 75 feet higher.

A NASA animation showing the dramatic loss of sea ice between 2005 and 2007 appears here—after a short commercial from ConocoPhillips.

What good are Category 5–strength levees if the sea level rises 75 feet?

We have it in our power to act, coordinate, to cut carbon emissions, to quickly develop alternative fuels—nuclear in particular: It’s closely monitored and doesn’t pollute or cause workplace injuries anywhere near coal’s rather reckless record. (See Gwyneth Cravens’s bold new book The Power to Save the World.)

If left to their own devices, Congress and the White House will never allocate serious money to research and development alternative energies—unless we demand it, over and over. • Go to the public officials on our Political Action page and tell them you want the U.S. as a whole to be serious about reducing our nation’s carbon emissions—from automobiles, industries, etc. Cut down on the excessive waste. Invest in new kinds of jobs—jobs that could stimulate the economy: Tell them to lay out some serious investment money for research and development of hybrid electric/gas automobiles, alternative energies, public transportation, industrial cleanliness,” and many other initiatives that public policy institutes and many others have proposed and only await investment and a fair chance to succeed.

Record Arctic Sea Ice Loss in 2007
Earth Observatory | NASA

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June through September 2007 brought record sea ice melt in the Arctic, well below the previous record low, set in September 2005. According to the National Snow and Ice Data Center (NSIDC), on September 16, 2007, sea ice extent dropped to 4.13 million square kilometers (1.59 million square miles)—38 percent below average and 24 percent below the 2005 record.

This image of the Arctic was produced from sea ice observations collected by the Advanced Microwave Scanning Radiometer (AMSR-E) Instrument on NASA’s Aqua satellite on September 16, overlaid on the NASA Blue Marble. The image captures ice conditions at the end of the melt season. Sea ice (white, image center) stretches across the Arctic Ocean from Greenland to Russia, but large areas of open water were apparent as well. In addition to record melt, the summer of 2007 brought an ice-free opening though the Northwest Passage that lasted several weeks. The Northeast Passage did not open during the summer of 2007, however, as a substantial tongue of ice remained in place north of the Russian coast.

The graph of sea ice melt shows the five-day mean sea ice extent for June through September, based on NSIDC’s Sea Ice Index. It compares values from 2007 with those from 2005 and the average (1979-2000). Although the 2007 melt season started out with slightly greater sea ice extent than 2005, melt accelerated in the second half of June, especially in the East Siberian Sea, where warm temperatures and clear skies hastened the ice’s retreat. From early July onward, ice extent remained below the levels of 2005. By early August—more than a month before the end of the melt season—the extent had already dropped below the minimum reached at the end of the 2005 melt season. The Arctic started to regain ice in mid-September, as summer came to a close.

Sea ice acts as the Earth’s built-in air conditioner. Because of its light color, Arctic sea ice reflects most of the sunlight reaching it back into space. In contrast, dark ocean water absorbs most of the sunlight. As sea ice continues melting, the increased exposure of ocean water changes the Earth’s albedo—the fraction of sunlight reflected away from the planet. This change in albedo can cause further warming, leading to continued sea ice melt and reinforcing the melting cycle. As summer melt continues to increase, wintertime recovery becomes more difficult to achieve. According to Mark Serreze, senior research scientist at NSIDC, Arctic sea ice could melt completely as early as 2030.

References

Cole, S. (2007, September 25) Remarkable drop in Arctic sea ice raises questions from NASA Goddard Space Flight Center. Accessed September 26, 2007.

Arctic Sea Ice News Fall 2007 from the National Snow and Ice Data Center. Accessed September 26, 2007.

The Cryosphere Today from The University of Illinois. Accessed September 26, 2007.

Arctic image courtesy NASA Goddard Scientific Visualization Studio, based on data from AMSR-E.

Graph courtesy Walt Meier, National Snow and Ice Data Center.