Fig. 17. Since 1900, salinity in the deep water of the Gotland Deep (Baltic Sea) has gradually
increased, and the 80/00 salinity isohaline has risen from 80 m water depth to 65 m. This means
that the volume of deep water below the halokline increased. The graph shows annual mean
salinity in 0/00. (According to data of Fonselius from Grasshoff 1974)
was the one with the least frequency of westwind weather conditions in 110 years.
From 1970-1975, such conditions were observed again more often.
ClimatolOgists are not in agreement on whether a reversal of this trend is starting to
take place, because a reversal of the trend has only been observed in the high northern
latitudes since 1970. In the central and equatorial part of the northern hemisphere,
the trend to lower ocean water temperatures has continued with teJ11perature declines
of 0.1 ° -O.2°C per decade (Kukla et al. 1977).
Changes of sea level may be responsible for the fact that seawater infusions into the
Baltic from the Skagerak are occurring less and less often and that the volume of
water of high salinity in the depths of the Baltic has increased (Fig. 17). In the Baltic
Sea region, post ice age changes in the coastal contour are still taking place. After all,
as a sea area the Baltic is only 7000 years old.
Naturally, the question of what influence the human population of neighboring
countries has on oxygen changes in the Baltic Sea is also being studied. In 1960, 1,5 g
of phosphorus per inhabitant were introduced into the Baltic via effluents. Through
phosphorus-containing detergents and increased agricultural and industrial production, the amount had risen to approximately 4 g of phosphorus per inhabitant by
1970. Like the tropical oceans, however, the surface water of the Baltic Sea is low in
nutrients because nutrients are constantly lost with dead plankton and plankton fecal
pellets that sink to the deeper levels.
24
increased, and the 80/00 salinity isohaline has risen from 80 m water depth to 65 m. This means
that the volume of deep water below the halokline increased. The graph shows annual mean
salinity in 0/00. (According to data of Fonselius from Grasshoff 1974)
was the one with the least frequency of westwind weather conditions in 110 years.
From 1970-1975, such conditions were observed again more often.
ClimatolOgists are not in agreement on whether a reversal of this trend is starting to
take place, because a reversal of the trend has only been observed in the high northern
latitudes since 1970. In the central and equatorial part of the northern hemisphere,
the trend to lower ocean water temperatures has continued with teJ11perature declines
of 0.1 ° -O.2°C per decade (Kukla et al. 1977).
Changes of sea level may be responsible for the fact that seawater infusions into the
Baltic from the Skagerak are occurring less and less often and that the volume of
water of high salinity in the depths of the Baltic has increased (Fig. 17). In the Baltic
Sea region, post ice age changes in the coastal contour are still taking place. After all,
as a sea area the Baltic is only 7000 years old.
Naturally, the question of what influence the human population of neighboring
countries has on oxygen changes in the Baltic Sea is also being studied. In 1960, 1,5 g
of phosphorus per inhabitant were introduced into the Baltic via effluents. Through
phosphorus-containing detergents and increased agricultural and industrial production, the amount had risen to approximately 4 g of phosphorus per inhabitant by
1970. Like the tropical oceans, however, the surface water of the Baltic Sea is low in
nutrients because nutrients are constantly lost with dead plankton and plankton fecal
pellets that sink to the deeper levels.
24