Bjorck, S. and Clemmensen, L.B. 2004. Aeolian sediment in raised bog deposits, Halland, SW Sweden: a new proxy record of Holocene winter storminess variation in southern Scandinavia? The Holocene 14: 677-688.
What was done
Cores of peat taken from two raised bogs in the near-coastal part of Halland, Southwest Sweden (Boarps Mosse and Hyltemossen), were examined for their content of wind-transported clastic material via a systematic count of quartz grains of diameter 0.2-0.35 mm and larger than 0.35 mm to determine temporal variations in Aeolian Sand Influx (ASI), which is correlated with winter wind climate in that part of the world.
What was learned
The authors report that "the ASI records of the last 2500 years (both sites) indicate two timescales of winter storminess variation in southern Scandinavia." Specifically, they note that "decadal-scale variation (individual peaks) seems to coincide with short-term variation in sea-ice cover in the North Atlantic and is thus related to variations in the position of the North Atlantic winter season storm tracks," while "centennial-scale changes - peak families, like high peaks 1, 2 and 3 during the Little Ice Age, and low peaks 4 and 5 during the Medieval Warm Period - seem to record longer-scale climatic variation in the frequency and severity of cold and stormy winters."
Bjorck and Clemmensen also found a striking association between the strongest of these winter storminess peaks and periods of reduced solar activity. They specifically note, for example, that the solar minimum between AD 1880 and 1900 "is almost exactly coeval with the period of increased storminess at the end of the nineteenth century, and the Dalton Minimum between AD 1800 and 1820 is almost coeval with the period of peak storminess reported here." In addition, they say that an event of increased storminess they dated to AD 1650 "falls at the beginning of the Maunder solar minimum (AD 1645-1715)," while further back in time they report high ASI values between AD 1450 and 1550 with "a very distinct peak at AD 1475," noting that this period coincides with the Sporer Minimum of AD 1420-1530. In addition, they call our attention to the fact that the latter three peaks in winter storminess all occurred during the Little Ice Age and "are among the most prominent in the complete record."
Last of all, Bjorck and Clemmensen report that degree of humification (DOH) intervals "correlate well with the classic late-Holocene climatic intervals," which they specifically state to include the Modern Climate Optimum (100-0 cal. yr BP), the Little Ice Age (600-100 cal. yr BP), the Medieval Warm Period (1250-600 cal. yr BP), the Dark Ages Cold Period (1550-1250 cal. yr BP) and the Roman Climate Optimum (2250-1550 cal. yr BP).
What it means
Winter storms throughout southern Scandinavia were more frequent and intense during the multi-century Dark Ages Cold Period and Little Ice Age than they were during the Roman Warm Period, Medieval Warm Period and Modern Warm Period, providing strong evidence to refute the climate-alarmist contention that storminess tends to increase during periods of greater warmth. Actually, just the opposite is generally found to be true, not only here but in most other parts of the world, as may be readily appreciated by reviewing the materials we have posted in our Subject Index under the general heading of Weather Extremes (Storms).
Reviewed 27 October 2004