Arctic Yearbook 2012
Østreng
265
free Arctic Ocean in summer by 2050. This scenario implies that the physical occurrence of multi-
year ice can possibly disappear from these waters in the future improving further the conditions of
economic activities in the Central Arctic Basin as well as along the NEP and NWP.
This is not to say that the Arctic Ocean will be ice-free in winter. As concluded in the AMSA study:
“Even after the first ice-free summer is recorded, there will almost certainly be subsequent years
when all of the ice does not melt in summer but survives to become ‘old’ ice the following year. It
is...generally agreed that the Arctic waters will continue to freeze over in winter” (AMSA, 2009: 26).
Let us illustrate the point: in mid-September 2007, the Arctic Ocean reached its absolute sea ice
minimum so far covering only 4.1 million sq km. One year later – in September 2008 – the extent of
sea ice was about 1 million sq km bigger than at the same time the year before, covering 5.2 million
sq kilometres (Doyle, 2008). In March 2008, the ice extent rebounded rapidly to a winter maximum
that was actually higher than in the previous four years. On these grounds, sea ice-experts expect
strong natural variability events in the future, causing both decreases and increases of the Arctic sea-
ice cover on seasonal and decadal time scales (Johannessen, 2008: 52). Thus, different sources
assume sea ice to be a lasting characteristic of the Arctic Ocean, although still very different from the
conditions 30 years back.
Ever since 1978 the sea ice extent has been declining. This trend is most pronounced at the end of
September, but all months show a declining trend. However, the retreat introduces the dangerous
polar lows
to new areas of the Arctic Ocean.
Polar lows
are high latitude, maritime small-scale cyclones
caused by cold air interacting with relatively warm open oceans. These cyclones, which are difficult
to forecast, appear suddenly and unexpectedly and are often associated with strong surface winds
and heavy snowfall. They usually originate north of 70
°N
and practically all move in a southward
direction.
Polar lows
are not found solely in the Arctic as they also appear in southern waters, such as
near Japan (Mauritzen and Kolstad, 2011: 25-36). Recent studies suggest, however, that the
likelihood of
polar lows
to occur in open waters for various reasons will decrease over time, whereas
“…the retreat of sea ice will expose large new ocean regions to the atmosphere. In these regions,
where
polar lows
and related weather have been non-existent so far (because
polar lows
need energy
from the oceans),
polar lows
will make their first appearances in the future. These are the same regions
that have been proposed as tomorrow’s shipping lanes and oil/gas exploration areas” (Mauritzen and
Kolstad, 2011: 34). Here, improvement in one operational condition for ships and oil rigs – retreat of