Arctic Yearbook 2012
Humpert and Raspotnik
287
A new study shows that multi-year ice, which is the oldest and thickest Arctic sea ice, is disappearing
at a faster rate than the younger and thinner ice which can typically be found at the edges of the
Arctic Ocean’s floating ice cap (Comiso, 2012). According to Comiso "the average thickness of the
Arctic sea ice cover is declining because it is rapidly losing its thick component, the multi-year ice. At
the same time, the surface temperature in the Arctic is going up, which results in a shorter ice-
forming season” (as cited in Gran & Viñas, 2012).
While the rapid decrease in multi-year ice in the Arctic Ocean will improve the possibility of
navigation during all seasons, significant obstacles to shipping, such as icing from sea spray, wind
chill, remoteness and its implications for rescue and emergency operations, limited reliable weather
forecasts, and polar lows, will remain. During the winter and spring months ice conditions along the
NSR and the TSR will remain heavy and the number of floating sea ice and icebergs, a hazard to the
safety of marine transport, may increase during the early melt season as ice floes break apart and drift
across the Arctic Ocean (Det Norske Veritas, 2010).
Sea ice will continue to form during the winter months, but the more hazardous multi-year ice, the
principal obstacle to shipping in Arctic Ocean, will cease to exist. With it, the ice-free period along
the Arctic’s main shipping routes is expected to increase from around 30 days in 2010 to more than
120 days by mid-century (Byers, 2009; Borgerson, 2009).
Furthermore, the distribution of the remaining ice will not occur uniformly across the Arctic Ocean.
According to Pfirman et al. sea ice will continue to collect and persist in one small area along the
northern flanks of the Canadian Archipelago and Greenland. The study suggests that perennial ice is
likely to survive longer in that region than anywhere else in the Arctic. The refugium does not only
rely on locally created ice but is fed by drifting ice that forms originally over the central Arctic. Even
the Siberian shelf seas may become a source of ice to that region (Pfirman, Tremblay, Newton &
Fowler, 2010). Such distribution and flow of sea ice away from the navigational channels of the NSR
and the TSR may lengthen the ice-free period along these routes. Moreover, ice-free periods along
the TSR may soon exceed forecasts, as current climate models tend to underestimate the rate of sea
ice retreat (Stroeve, Holland, Meier, Scambos & Serreze, 2007).