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collection of “numbers” and their manipulation. It is much more about obtaining a fundamental
appreciation of the hydrological cycle that explains how a large and complex ocean system works.
Similarly the freshwater in the Hudson Bay complex, whether in the form of river runoff, sea ice, sea-ice
melt, precipitation or evaporation is extremely important to regional climate as well as to the circulation,
stratification and biological production of the marine ecosystem.
Especially since 1992, the system has been warming. For the period from 1926–2009, 12 of the 19
warmest years occurred after 1991 (Galbraith & Larouche, 2011). While the warming trend, largely
attributable to the accumulation of greenhouse gases in the atmosphere, appears to be relentless and
apparently increasing, there is significant annual and multi-year variability in air and sea surface
temperatures (up to 5 Cº). Annual and multiyear variations in temperatures are associated with
atmospheric and oceanic oscillations such as the North Atlantic (NAO) and the Southern oscillation index
(SOI). The East Pacific/North Pacific indices (EP/NP) and the Arctic oscillation (AO) and North Pacific index
are related to subsequent surface air and sea temperatures and ice cover in Hudson Bay.
Other climate-forcing events also play a role. The Mount Pinatubo eruption in the Philippines in June 1991
led to a drop of about 0.5ºC in mean global temperatures in 1992, and in the Hudson Bay region the
surface air temperatures were typically more than one degree lower than that expected based on the
regional long-term trend line. Surface air temperatures, surface sea temperatures, concentrations of ice
and break-up and freeze-up dates are correlated in the Hudson Bay region. Winds over Hudson Bay are
also correlated with ice break-up and sea surface temperatures, probably because of their influence on
the direction and magnitude of ice movement over the bay (Hochheim, Lukovich, & Barber, 2011).
Recent regional trends in air temperatures, sea surface temperatures, and dates of ice break-up and
freeze-up are summarized in Table 1.
Table 1. Summary of recently reported trends in the climate of the Hudson Bay Complex
Indicator/source
Time frame Trends
Comment
Ice break-up
(Gagnon & Gough,
2005)
1971–2003 Statistically
significant
earlier
break-up (-0.4–1.25 days/year) in
James Bay, along the southern
shore of Hudson Bay and western
Hudson Bay.
Similar
though
not
statistically
significant
trends to earlier break-
up in almost all locations
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Ice
freeze-up
(Gagnon & Gough,
2005)
1971–2003 Statistically significant later freeze-
up (0.32–0.55 days/year) in
northern
and
northeastern
Hudson Bay
Similar
though
not
statistically
significant
trends to later freeze-up
at almost all locations
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Air temperature
at coastal stations
(Gagnon & Gough,
2005)
1971–2003 Statistically significant warming
trend (0.5–0.8ºC/decade) at seven
of eight stations.
The warming trend at
Inukjuak (0.4ºC/decade)
was
not
statistically
significant.
Ice
break-up
Hudson
Bay
(Stirling
and
Parkinson, 2006)
1978–2004 Statistically
significant
earlier
break-up (-0.75+/- 0.25 days per
year) in western Hudson Bay
The trend value in
Eastern Hudson Bay (-
0.14+/- o.31) was not
significant
Ice break-up Foxe
Basin (Stirling and
Parkinson, 2006)
1978–2004 Statistically
significant
earlier
break-up (-0.66+/- 0.20 days per
year)
Ice
break-up
Hudson
Bay
(Stirling
and
Parkinson, 2006)
1971–2009
1990–2009
Statistically
significant
earlier
break-up (-3.2 days/decade) from
1971–2009. Earlier break-up (-1.9
days /decade) after 1990 not
significant
Ice
break-up
dates
highly correlated with
surface air temperatures
and
sea
surface
temperatures
Ice break-up Foxe
Basin (Galbraith
and
LaRoche,
2011)
1971-2009
1990-2009
Statistically
significant
earlier
break-up (-4.9 days/decade) from
1971–2009 and 9.0 days/decade
after 1990
Ice
break-up
dates
highly correlated with
surface air temperatures
and
sea
surface
temperatures
Ice
break-up
Hudson
Strait
(Galbraith
and
LaRoche, 2011)
1971–2009
1990–2009
Statistically
significant
earlier
break-up (-5.6 days/decade) from
1971-2009 and 13.5 days/decade
after 1990
Ice
break-up
dates
highly correlated with
surface air temperatures
and
sea
surface
temperatures
Air temperatures
(Galbraith
and
LaRoche, 2011)
1926–2009 Warming trend after 1992 with 12
of the 19 warmest years on record
(1926–2009) occurring after 1992.
Sea
surface
temperatures
(Galbraith
and
LaRoche, 2011)
1985–2009 Warmest week of the year
trending to higher temperatures.
Most
areas
with
significant
increases (0.2–1.4ºC/decade)
Warmest temperatures
correlated
with
air
temperatures
and,
especially, the date of
break-up.