Climatic Variation and Changes in the Wind and Ocean Circulation: The Little Ice Age in the Northeast Atlantic

Abstract

Variations must take place in the ocean circulation when the general wind circulation varies. There are hints even within recent years that the variations in the ocean between Iceland and Scotland and Norway can be big: The area has been regarded as the main path of the warm, saline North Atlantic Drift water heading towards the Arctic; but, when the polar water occasionally intrudes from the north, sea-surface temperature is liable to fall by 3 to 5°C and presumably by more than this when, as in 1888, the ice advanced to near the Faeroe Islands. The long series of sea-surface temperature observations at that point, starting in 1867, and earlier observations covering the area in 1789, are studied. Various kinds of proxy data—notably the CLIMAP Atlantic ocean-bed core analysis results for the last Ice Age climax and cod fishery and sea-ice reports from the Little Ice Age in the 17th century AD —are then used to indicate the variability in this part of the ocean on longer time scales. The reconstruction of the situation between ad 1675 and 1705 resulting from this study suggests a probable mean departure of the sea surface temperature from modern values between the Faeroes and southeast Iceland amounting to about −5°C; and at the climax in 1695 the polar water seems to have spread all around Iceland, across the entire surface of the Norwegian Sea to Norway, and south to near Shetland. Support for this diagnosis is found in a considerable variety of reports of environmental conditions existing at the time in Scotland, south Norway and elsewhere. The enhanced thermal gradient between approximately latitudes 55 and 65°N during the Little Ice Age, which this result indicates, offers an explanation for the occurrence in that period of a number of windstorms which changed the coasts in various places and seem to have surpassed in intensity the worst experienced in the region in more recent times.

Bjerknes’ hypothesis on the coldness during AD 1790–1820 revisited

“…The strength of the cyclones in mid-latitudes changed too; a higher occurrence probability of the strongest cyclones was observed under Dalton Minimum atmospheric circulation conditions. This is consistent with the notion that some storms in the colder periods of the Little Ice Age period exceeded twentieth century extremes in intensity (Lamb 1979;Glaser 2001), at least for the European mid-latitudes. To a large extend this increase in cyclone frequency can be related to a redistribution of cyclone activity rather than being attributed solely to increased baroclinicty.…”

“…The decrease in sea surface temperatures in the northeastern North Atlantic, including the North Sea and the Norwegian Sea associated with this compares well with a reconstruction of SSTs in the summer of 1789 on the basis of results of an expedition (Lamb 1979, Fig. 11), showing a decrease of 0.5-1.0°C in the waters invading the northern North Atlantic and the North Sea.…”

Sea Ice, Climate, and Icelandic Fisheries in the Eighteenth and Nineteenth Centuries

“…It has been suggested, for example, that the failure of the Faeroese cod fishery during the 17th and 18th centuries was due to a reduction in sea-surface temperatures (Lamb, 1979). This issue has also been discussed by Jónsson (1994b), and Ogilvie (1982Ogilvie ( , 1997.…”

Sediment transport and deposition during extreme sea storm events at the Salerno Bay (Tyrrhenian Sea): comparison of field data with numerical model results

“…(Ingram et al, 1978;Bradley and Jones, 1993) occurred from the middle of the 15th century to the 19th century, with a likely higher intensity of exceptional winter storms (Lamb, 1979;Dawson et al, 2004). The oldest event bed (T3), might be coeval to the definitive desertion of the ancient town Paestum, close to the studied area, due to alluvial cover and drowning of the area (Violante et al, 2001).…”