International Polar Year 2007–2008 - WMO

Fig. 2.2-15 The
position of the ice
edge relative to
the circum-Arctic
shelf-break acts as a
sensitive ‘switch’ for
the onshore flux of
salt (Carmack et al.,
pers. comm.).
180
IPY 20 07–20 08
exposing an ever increasing fraction of the sea surface
to solar radiation and increasing the habitat suitable
for phytoplankton growth, we can well appreciate
that the unprecedented loss of arctic sea-ice in
recent years must have had some significant effect on
marine primary production across the Arctic basins
and shelves. Hitherto, however, we have had no clear
idea of where and how much. In two recent papers
(Pabi et al., 2008; Arrigo et al., 2008), a Stanford Group
have now quantified that impact. By coupling satellitederived
sea ice, SST and chlorophyll to a primary
production algorithm parameterized for Arctic waters,
they find 1) that annual pan-Arctic primary production
(419 ± 33 Tg C a-1 on average during 1998–2006) was
roughly equally distributed between pelagic waters
(less productive, but greater area) and waters located
over the continental shelf (more productive, but
smaller area); 2) that annual primary production in the
Arctic has increased yearly by an average of 27.5 Tg C
yr- 1 since 2003 and by 35 Tg C yr- 1 between 2006 and
2007; and 3) that 30% of this increase is attributable
to decreased minimum summer ice extent and 70%
to a longer phytoplankton growing season. Arrigo
et al., (op cit) suggest that if these trends continue,
the additional loss of ice during Arctic spring ‘could
boost productivity >3-fold above 1998–2002 levels,
potentially altering marine ecosystem structure and
the degree of pelagic-benthic coupling. Changes
in carbon export could in turn modify benthic
denitrification on the vast continental shelves’.
IPY on the Canadian Arctic shelf: the Circumpolar
Flaw Lead System Study. The Circum polar
Flaw Lead (CFL) system study was a Canadian-led
multidisciplinary initiative for IPY with over 350
participants from 12 countries. The CFL is a perennial
characteristic of the Arctic, that forms when the central
pack ice (which is mobile) moves away from coastal
fast ice, opening a flaw lead which occurs throughout
the winter season. The flaw lead is circumpolar in
nature, with recurrent and interconnected polynyas
occurring in the Norwegian, Icelandic, North American
and Siberian sectors of the Arctic. Due to a reduced
ice cover, these regions are exceedingly sensitive
to physical forcings from both the atmosphere and
ocean and provide a unique laboratory from which
we can gain insights into the changing polar marine
ecosystem. This study examines the importance of
climate processes in the changing nature of a flaw lead
system in the northern Hemisphere and the effect
these changes will have on the marine ecosystem,
contaminant transport, carbon flux and greenhouse
gases. The CFL study was 293 days in duration and
involved the overwintering of the CCGS Amundsen
icebreaker in the Cape Bathurst flaw lead throughout
the winter of 2007–2008. This represented the first
time an icebreaker had overwintered an entire winter
in the Arctic while remaining mobile in a flaw lead.
The CFL field season commenced in fall 2007.
Between 18 October and 27 November 2007, 74
unique open-water sites were sampled (Fig. 2.2-16a)
and multiple moorings were collected and redeployed
throughout the Amundsen Gulf region. On November
28 2007, the ship entered its ‘drift mode’, during which
the ship parked in a piece of ice that was large, thick
and homogeneous enough for setting up equipment
and collecting samples, until conditions or ice
movement necessitated a move to another location.
A total of 44 drift stations averaging 3 ± 4 days (max.
22 days) were sampled between 28 November 2007
and 31 May 2008, generally located on the northern
side of the Amundsen Gulf to the south of Banks Island
(Fig. 2.2-16b). Though the initial project plan had
called for the establishment of a semi-permanent ice
camp on the ice bridge that typically forms between
Banks Island and Cape Perry, this ice bridge never in
fact formed. During the melt season of May and June,
several fast ice sites were sampled to follow the ice