Jökull - 01.12.1969, Blaðsíða 7

influence begins to be felt around the turn of
the year. In January and February the ice
ntargin advances considerably eastward between
the 75th parallel and a point well north of
Iceland. This is due to new ice, partly in wakes
within the Polar ice and partly at its margin.
But the common opinion, to consider this
growth of the Greenland Ice as an immediate
menace to Iceland, is not justified by facts. As
a rule, the ice shrinks gradually during March
to May — very likely because the “surge” of
the main Greenland Current gradually trans-
ports all the accumulated new ice. Statistics
support this, and a good demonstration of the
process was given in 1966, as shown in Fig. 4
(after the ice charts of the British Weather
Bureau). From this picture it may be inferred
that ice conditions at Iceland are hardly or not
dependent on conditions in the area north of
Jan Mayen. This is also evident from another
fact: the position of the average ice margin in
late winter, from Icelandic waters up to about
the 75th parallel, has not changed much
since 1898 (Danish and British ice charts).
Every winter there have, on the average, been
the same huge rnasses of drift north of Iceland
but their menace to the country has changed
very much with the climate after about 1920.
The main causes of the menace must be sought
in weather conditions in the neighbourhood of
Iceland.
As a further evidence for this conclusion, it
can be mentioned that the severity of ice condi-
tions at the coasts of Iceland shows no clear
Fig. 3. Average position of the ice margin
(density of pack 4/10) at the end of the
months August, November, and February
since 1962, according to the ice charts of the
British Weather Bureau.
JÖKUL.L 19. ÁR 3