Arctic sea ice is set to reach its lowest ever recorded extent confirming fears that the effects of man-made climate change are having a major impact on the polar region.
With the melt happening at an unprecedented rate of more than 100,000 sq km a day, and at least a week of further melt expected before ice begins to reform ahead of the northern winter, scientists are expected to confirm the record – currently set in 2007 – within days.
Daily records at the National Snow and Ice Data Centre say Arctic sea ice extent during the first two weeks of August continued to track below 2007 record low daily ice extents.
As of August 13, ice extent was already among the four lowest summer minimum extents in the satellite record, with about five weeks still remaining in the melt season.
Sea ice extent dropped rapidly between August 4 and August 8. While this drop coincided with an intense storm over the central Arctic Ocean, it is unclear if the storm prompted the rapid ice loss. Overall, weather patterns in the Arctic Ocean through the summer of 2012 have been a mixed bag, with no consistent pattern.
Arctic sea ice extent on August 13 was 5.09 million square kilometers (1.97 million square miles). This is 2.69 million square kilometers (1.04 million square miles) below the 1979 to 2000 average extent for the date, and is 483,000 square kilometers (186,000 square miles) below the previous record low for the date, which occurred in 2007.
The average pace of ice loss since late June has been rapid at just over 100,000 square kilometers (38,000 square miles) per day.
However, this pace nearly doubled for a few days in early August during a major Arctic cyclonic storm, discussed below. Unlike the summer of 2007 when a persistent pattern of high pressure was present over the central Arctic Ocean and a pattern of low pressure was over the northern Eurasian coast, the summer of 2012 has been characterized by variable conditions.
Air tempertures about 3000 feet above the ocean surface of 1 to 3 degrees Celsius (1.8 to 5.4 degrees Fahrenheit) above the 1981 to 2012 average have been the rule from central Greenland, northern Canada, and Alaska northward into the central Arctic Ocean.
Cooler than average conditions (1 to 2 degrees Celsius or 1.8 to 3.6 degrees Fahrenheit) were observed in a small region of eastern Siberia extending into the East Siberian Sea, helping explain the persistence of low concentration ice in this region through early August. Ice volume in the Arctic has declined dramatically over the past decade. The 2011 minimum was more than 50% below that of 2005.
According to the Polar Science Centre at the University of Washington it now stands at around 5,770 cubic kilometres, compared with 12,433 cu km during the 2000s and 6,494 cu km in 2011. The ice volume for 31 July 2012 was roughly 10% below the value for the same day in 2011. A new study by UK scientists suggests that 900 cu km of summer sea ice has disappeared from the Arctic ocean over the past year.
Arctic sea ice keeps the polar regions cool and helps moderate global climate. Sea ice has a bright surface; 80 percent of the sunlight that strikes it is reflected back into space. As sea ice melts in the summer, it exposes the dark ocean surface. Instead of reflecting 80 percent of the sunlight, the ocean absorbs 90 percent of the sunlight. The oceans heat up, and Arctic temperatures rise further.
A small temperature increase at the poles leads to still greater warming over time, making the poles the most sensitive regions to climate change on Earth.
According to scientific measurements, both the thickness and extent of summer sea ice in the Arctic have shown a dramatic decline over the past thirty years. This is consisistent with observations of a warming Arctic. The loss of sea ice also has the potential to accelerate global warming trends and to change climate patterns.