Tag Archives: ice

Mapping Greenland’s melt

The same arctic weather patterns that have been cooling N. Europe and the Eastern USA have been warming Greenland as is shown in NASA’s image of the day Record Melting in Greenland during 2010:

2010 was an exceptional year for Greenland’s ice cap. Melting started early and stretched later in the year than usual. Little snow fell to replenish the losses. By the end of the season, much of southern Greenland had set a new record, with melting that lasted 50 days longer than average.

This image was assembled from microwave data from the Special Sensor Microwave/Imager (SSM/I) of the Defense Meteorological Satellites Program. Snow and ice emit microwaves, but the signal is different for wet, melting snow than for dry. Marco Tedesco, a professor at the City College of New York, uses this difference to chart the number of days that snow is melting every year. This image above shows 2010 compared to the average number of melt days per year between 1979 and 2009.

When snow melts, the fine, bright powder turns to larger-grained, gravely snow. These large grains reflect less light, which means that they can absorb more energy and melt even faster. When the annual snow is melted away, parts of the ice cap are exposed. The surface of the ice is also darker than snow. Since dark ice was exposed earlier and longer in 2010, it absorbed more energy, leading to a longer melt season. A fresh coat of summer snow would have protected the ice sheet, but little snow fell.

Social Implications of Arctic Melting

An article Arctic Meltdown in Foreign Affairs by Scott G. Borgerson discusses the political and economics consequences on a ice-free summer Arctic:

The shipping shortcuts of the Northern Sea Route (over Eurasia) and the Northwest Passage (over North America) would cut existing oceanic transit times by days, saving shipping companies — not to mention navies and smugglers — thousands of miles in travel. … Taking into account canal fees, fuel costs, and other variables that determine freight rates, these shortcuts could cut the cost of a single voyage by a large container ship by as much as 20 percent — from approximately $17.5 million to $14 million — saving the shipping industry billions of dollars a year. The savings would be even greater for the megaships that are unable to fit through the Panama and Suez Canals and so currently sail around the Cape of Good Hope and Cape Horn. Moreover, these Arctic routes would also allow commercial and military vessels to avoid sailing through politically unstable Middle Eastern waters and the pirate-infested South China Sea. An Iranian provocation in the Strait of Hormuz, such as the one that occurred in January, would be considered far less of a threat in an age of trans-Arctic shipping.

Arctic shipping could also dramatically affect global trade patterns. … As soon as marine insurers recalculate the risks involved in these voyages, trans-Arctic shipping will become commercially viable and begin on a large scale. In an age of just-in-time delivery, and with increasing fuel costs eating into the profits of shipping companies, reducing long-haul sailing distances by as much as 40 percent could usher in a new phase of globalization. Arctic routes would force further competition between the Panama and Suez Canals, thereby reducing current canal tolls; shipping chokepoints such as the Strait of Malacca would no longer dictate global shipping patterns; and Arctic seaways would allow for greater international economic integration. When the ice recedes enough, likely within this decade, a marine highway directly over the North Pole will materialize. Such a route, which would most likely run between Iceland and Alaska’s Dutch Harbor, would connect shipping megaports in the North Atlantic with those in the North Pacific and radiate outward to other ports in a hub-and-spoke system. A fast lane is now under development between the Arctic port of Murmansk, in Russia, and the Hudson Bay port of Churchill, in Canada, which is connected to the North American rail network.

Continue reading

Ice minima

Arctic sea ice has reached record low coverage in 2007.

Ice minima


This image shows the Arctic as observed by the Advanced Microwave Scanning Radiometer for EOS (AMSR-E) aboard NASA’s Aqua satellite on September 16, 2007. In this image, blue indicates open water, white indicates high sea ice concentration, and turquoise indicates loosely packed sea ice. The black circle at the North Pole results from an absence of data as the satellite does not make observations that far north.

Three contour lines appear on this image. The red line is the 2007 minimum, as of September 15, and it almost exactly fits the sea ice observed by AMSR-E. Depending on the calculations, the minimum occurred on September 14 (one-day running average) or September 16 (five-day running average). The green line indicates the 2005 minimum, the previous record low. The yellow line indicates the median minimum from 1979 to 2000.