Geoscience Reference
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in volume-averaged salinity between the Pacific and the Atlantic oceans suggest changes in
freshwater transport between these ocean basins. The pattern of salinity changes is compat-
ible with changes in the hydrological cycle, in particular with changes in precipitation and
inferred larger water transports in the atmosphere from low to higher latitudes and from
the Atlantic to the Pacific. The results of the analysis of model simulations by Sarmiento
et al
. (
2004
) agree with the response of the salinity distribution to an overall enhancement
of the atmospheric hydrological cycle, due to the increased moisture bearing capacity of
the warmer air. The subtropical region of high evaporation generally becomes saltier, while
high-latitude areas of greater rainfall become fresher. The temperature and salinity changes
result in an overall reduction of the surface water density, which can be expected to lead to
increased vertical stratification and possibly reduced nutrient supply to the euphotic zone.
The model simulations also show a reduction of the winter maximum surface mixed layer
depth, especially at latitudes greater than 40°.
In the Arctic the ice cover shrank by 2.7%/decade between 1979 and 2009, with a
However, summer minimum sea ice cover for the years 2007-2012 has shown to be the six
lowest years of summer minimum sea ice cover observed; the record low summer sea ice
cover in 2012 was only 51% of the average for the years 1979-2000 (US National Snow
and Ice Data Center,
2012
). Variability of salinity and temperature in areas of Icelandic
and Faeroese waters has been observed over several decades in the associated shelf and
tury 1870-1970 shows a high at around 1870-1875, a rather persistent low over the period
1880-1915, followed by above average for 1925-1965. Temperature and salinity observa-
tions in late spring in the same region north of Iceland over the half-century 1950-2000
show deviations from the 1961-1980 mean at roughly decadal time-scales. The temperat-
ure is up to about 2 °C above average over the period 1950-1960, about 2 °C below in the
1960s, with the coldest period in 1965-1971, and subsequent oscillations of about +/− 1.5
°C, with positive values in the 1990s. Similar variability occurs in the salinity records. In
both there are marked interannual variations. These observations also demonstrate the vari-
