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Daily Journals

August 31, 2006

While waiting to disembark at Ice Station 3 (81° 29.44' N, 133° 48.43') this afternoon, I took note on how cold it looked out on the ice. It was -6 °C and snowing. The wind was blowing so hard that the snow was “falling” horizontally. Because there were many melt water ponds at this station, Alexander, a crew member with a lot of ice experience, went onto the ice before anyone else and marked danger zones with flags.

Alexander with PeshniaWhen Alexander was finished marking the ice, he escorted Art and I away from the designated research sites so we could take some photos. As he walked ahead of us, he tested the ice with a simple piece of gear known variously as an ice chisel (US), a Bodger (UK) or a Peshnia (how it sounds in Russian — no clue on how it is spelled). The Peshnia is a long piece of iron that is chisel-shaped on the bottom edge and attached to a stout wooden handle. As Alexander walked along, he looked at the ice with an experienced eye and periodically jabbed the Peshnia into the ice. The rule of thumb here in the Arctic is that if you hit the ice hard with the Peshnia and it doesn't go through, the ice is thick enough to stand on. If you hit water, you had better take a step back. It is said that a human can stand on ice that is one inch thick; but as one scientist said, "Not me." I heartily agree.

As Art and I explored Ice Station 3 with Alexander, the science teams began installing instruments and collecting data. One of the instruments deployed at each ice station is an Ice Mass Balance Buoy (IMB). Bruce Elder of the US Army Corps of Engineers Cold Regions Research and Engineering Laboratory (CRREL) is in charge of installing IMBs during this trip.

The IMB is used to measure and attribute changes in the thickness of the Arctic sea ice cover. Since sea ice acts as a buffer between the ocean and atmosphere, the IMB may be an effective way to monitor and predict climate change. IMB data can also validate and calibrate satellite-based ice measurement insturments. The IMB is installed directly into the ice cover and transmits via satellite air and sea temperature, snow cover and ice thickness data every two hours. It has a battery life of 2–3 years. Data from various IMB stations (including the ones from this expedition) may be accessed at http://imb.crrel.usace.army.mil/.

Before reaching today’s ice station there had been a lull in the scietific activity over the past 24 hours. Taking advantage of the lull, I talked to a number of researchers onboard and learned a lot about polar sea ice — its formation and its movements — and the importance of Artic research.

People often think of icebergs when they visualize polar waters; but icebergs are actually derived from land-based glaciers and ice sheets. The sea ice in polar waters is frozen seawater.

grease iceAs a layer of seawater gets ready to turn into sea ice, millions of ice crystals form just below the ocean’s surface, creating a mixture known as frazil ice. As temperatures approach the freezing point of seawater (about -2 °C), the mixture thickens and congeals into what is called grease ice. From a distance, grease ice looks like oil slicks on the water's surface. Upon closer inspection grease ice looks like a gray, slushy blob and has the consistency of a convenience store icy drink. (The cooling temperatures of the approaching Arctic autumn are triggering large-scale ice formation and we are beginning to see a lot of grease ice as we travel through open water.)

In winter, polar sea ice covers an area of the Arctic Ocean larger than the continental United States. In a normal year, first-year sea ice can grow up to 2 m thick. Thicker ice is formed only when ice — first-year or older — gets piled up in ridges or when it remains in the Arctic Ocean for several winters and accumulates at a faster rate than it melts.

A surprise for many is that Arctic sea ice is in motion. Two major circulation patterns that have been observed are the Transpolar Drift and the Beaufort Gyre. The Transpolar Drift carries ice westward from coastal seas in the Russian Arctic across the Arctic Ocean into Fram Strait between Greenland and Svalbard. It can take one to three years for ice formed along the Russian coast to exit via Fram Strait. The Beaufort Gyre is located off the Alaskan and Canadian coasts and rotates in a clockwise motion. Ice caught in the Beaufort Gyre can drift for a few years before being caught up in the Transpolar Drift and sent out to the Greenland Sea.

If summer sea ice disappears in the next 20 to 50 years, as some models predict, what will be the consequences? Why should anyone living in North Carolina or elsewhere in the temperate zone care? There might be positive economic benefits as the disappearance of summer sea ice would undoubtedly open up shipping lanes in the far north, allowing shorter and therefore more economical trade routes. But there are many unknowns.

What will happen to polar bears, seals and other wildlife dependent on the sea ice? How will the lifestyles of native peoples living at the edge of the Arctic be affected? And what of the global climate change we read about? Because sea ice is formed from existing seawater, melting it will not raise sea level — the melting of glaciers and land-based ice sheets will. Will sea ice decline lead to increased melting of land ice sheets in the Arctic? It certainly will change the heat balance of the Arctic Ocean through decreased reflectivity of solar radiation.

How sea ice change will influence global climate is uncertain, but scientists like those aboard this ship and elsewhere are trying to unravel those mysteries and obtain data that will make climate change models more accurate and help us better understand this complex Arctic system.

—Mike Dunn

 

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