A number of studies have reported increases in North Atlantic storminess over the last two decades of the 20th century (Jones et al., 1997; Gunther et al., 1998; Dickson et al., 2000). Since climate alarmists claim this period was one of the warmest - if not the warmest - of the past couple of millennia, this observation might appear to vindicate their view of the subject. When much longer time periods are considered, however, just the opposite is typically found to be the case.

In reviewing some of these more comprehensive analyses, we begin with the study of Dawson et al. (2002), who searched daily meteorological records from Stornoway (Outer Hebrides), Lerwick (Shetland Islands), Wick (Caithness) and Fair Isle (west of the Shetland Islands) for all data pertaining to gale-force winds over the period 1876-1996, which they used to construct a history of storminess for that period for northern and northwestern Scotland. This history indicated that although North Atlantic storminess and associated wave heights had indeed increased over the prior two decades, storminess in the North Atlantic region "was considerably more severe during parts of the nineteenth century than in recent decades." In addition, whereas the modern increase in storminess appeared to be associated with a spate of substantial positive values of the North Atlantic Oscillation (NAO) index, they say that "this was not the case during the period of exceptional storminess at the close of the nineteenth century." During that earlier period, the conditions that fostered modern storminess were apparently overpowered by something even more potent, i.e., cold temperatures, which in the view of Dawson et al. led to an expansion of sea ice in the Greenland Sea that expanded and intensified the Greenland anticyclone, which in turn led to the North Atlantic cyclone track being displaced farther south. Additional support for this view is provided by the hypothesis propounded by Clarke et al. (2002), who postulated that a southward spread of sea ice and polar water results in an increased thermal gradient between 50°N and 65°N that intensifies storm activity in the North Atlantic and supports dune formation in the Aquitaine region of southwest France.

The results of these two studies suggest that the increased storminess and wave heights observed in the European sector of the North Atlantic Ocean over the past two decades are not the result of global warming. Rather, they are associated with the most recent periodic increase in the NAO index. Furthermore, a longer historical perspective reveals that North Atlantic storminess was even more severe than it is now during the latter part of the nineteenth century, when it was significantly colder than it is now. In fact, the storminess of that much colder period was so great that it was actually decoupled from the NAO index. Hence, the long view of history suggests that the global warming of the past century or so has actually led to an overall decrease in North Atlantic storminess.

Additional evidence for the recent century-long decrease in storminess in and around Europe comes from the study of Bijl et al. (1999), who analyzed long-term sea level records from several coastal stations in northwest Europe. According to these researchers, "although results show considerable natural variability on relatively short (decadal) time scales," there is "no sign of a significant increase in storminess ... over the complete time period of the data sets." In the southern portion of the North Sea, however, where natural variability was more moderate, they did find a trend, but it was "a tendency towards a weakening [our italics] of the storm activity over the past 100 years."

Much the same results were obtained by Pirazzoli (2000), who analyzed tide-gauge, wind and atmospheric pressure data over the period 1951-1997 for the northern portion of the Atlantic coast of France. In that study, the number of atmospheric depressions (storms) and strong surge winds were found to be decreasing in frequency. In addition, it was reported that "ongoing trends of climate variability show a decrease in the frequency and hence the gravity of coastal flooding."

Tide-gauge data have also been utilized as proxies for storm activity in England. Based on high-water measurements made at the Liverpool waterfront over the period 1768-1999, Woodworth and Blackman (2002) found that the annual maximum surge-at-high-water declined at a rate of 0.11 ± 0.04 meters per century, suggesting that the winds responsible for producing high storm surges were much stronger and/or more common during the early part of the record (colder Little Ice Age) than the latter part (Modern Warm Period).

On a somewhat different front, and quite a ways inland, Bielec (2001) analyzed thunderstorm data from Cracow, Poland for the period 1896-1995, finding an average of 25 days of such activity per year, with a non-significant linear-regression-derived increase of 1.6 storm days from the beginning to the end of the record. From 1930 onward, however, the trend was negative, revealing a similarly-derived decrease of 1.1 storm days. In addition, there was a decrease in the annual number of thunderstorms with hail over the entire period and a decrease in the frequency of storms producing precipitation in excess of 20 mm.

In introducing a study they conducted in Switzerland, Stoffel et al. (2005) noted that debris flows are a type of mass movement that frequently causes major destruction in alpine areas; and they reported that since 1987 there had been an apparent above-average occurrence of such events in the Valais region of the Swiss Alps, which had prompted some researchers to suggest that the increase was the result of global warming (Rebetez et al., 1997). Consequently, Stoffel et al. used dendrochronological methods to determine if the recent increase in debris-flow events was indeed unusual, and if it appeared that it was, to see if it made sense to attribute it to CO2-induced global warming.

In extending the history of debris-flow events (1922-2002) back to the year 1605, they found that "phases with accentuated activity and shorter recurrence intervals than today existed in the past, namely after 1827 and until the late nineteenth century." What is more, the nineteenth century period of high-frequency debris flow was shown to coincide with a period of higher flood activity in major Swiss rivers, while less frequent debris flow activity after 1922 corresponded with lower flooding frequencies. In addition, debris flows from extremely large mass movement events, similar to what occurred in 1993, were found to have "repeatedly occurred" in the historical past, and to have been of such substantial magnitude that, in the opinion of Stoffel et al., the "importance of the 1993 debris-flow surges has to be thoroughly revised."

The results of Stoffel et al.'s study demonstrate that the apparent above-average number of debris flow events since 1987 was just that - apparent. In fact, they report that debris flows occurred "ever more frequently in the nineteenth century than they do today." As a result, they concluded that "correlations between global warming and modifications in the number or the size of debris-flow events, as hypothesized by, e.g., Haeberli and Beniston (1998), cannot, so far, be confirmed in the study area."

These findings clearly demonstrate the importance of evaluating the uniqueness of earth's contemporary climatic state - or the uniqueness of recent trends in various climate-related phenomena - over a much longer time span than just the past century or, even worse, merely a portion of it; for only when a multi-centennial or millennial view of the subject is available can one adequately evaluate the uniqueness of a climate-related phenomenon's recent behavior, let alone link that behavior to late 20th-century or early 21st-century global warming.

Noting that "a great amount of evidence for changing storminess over northwestern Europe is based on indirect data and reanalysis data rather than on station wind data," Smits et al. (2005) investigated trends in storminess over the Netherlands based on hourly records of 10-m wind speed observations made at thirteen meteorological stations scattered across the country that have uninterrupted records for the time period 1962-2002. This effort led to their discovery that "results for moderate wind events (that occur on average 10 times per year) and strong wind events (that occur on average twice a year) indicate a decrease in storminess over the Netherlands [of] between 5 and 10% per decade."

Moving cross-continent to the south and west, Raicich (2003) analyzed 62 years of sea-level data for the period 1 July 1939 to 30 June 2001 at Trieste, in the Northern Adriatic, to determine historical trends of surges and anomalies. This work revealed that weak and moderate positive surges did not exhibit any definite trends, while strong positive surges clearly became less frequent, even in the face of a gradually rising sea level, "presumably," in the words of Raicich, "as a consequence of a general weakening of the atmospheric activity," which was also found to have been the case for Brittany by Pirazzoli (2000).

Further north, Bjorck and Clemmensen (2004) extracted cores of peat from two raised bogs in the near-coastal part of southwest Sweden, from which they derived histories of wind-transported clastic material via systematic counts of quartz grains of various size classes that enabled them to calculate temporal variations in Aeolian Sand Influx (ASI), which has been shown to be correlated with winter wind climate in that part of the world. In doing so, they found 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 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, the two researchers 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). There would thus appear to be little doubt that 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, the Medieval Warm Period and the Modern Warm Period, providing strong evidence to refute the climate-alarmist contention that storminess tends to increase during periods of greater warmth. In the real world, just the opposite would appear to be the case.

Also working in Sweden were Barring and von Storch (2004), who - speaking of windstorms - say that with the perspective of anthropogenic climate change, the occurrence of such extreme events may "create the perception that ... the storms lately have become more violent, a trend that may continue into the future." Therefore, with the intent to test this inference, and relying on data, rather than perception to address the topic, these two researchers analyzed long time series of pressure readings for Lund (since 1780) and Stockholm (since 1823), analyzing (1) the annual number of pressure observations below 980 hPa, (2) the annual number of absolute pressure tendencies exceeding 16 hPa/12h, and (3) intra-annual 95th and 99th percentiles of the absolute pressure differences between two consecutive observations. Via these means they determined that the storminess time series they developed "are remarkably stationary in their mean, with little variations on time scales of more than one or two decades." In this regard, for example, they note that "the 1860s-70s was a period when the storminess indices showed general higher values," as was the 1980s-90s, but that, subsequently, "the indices have returned to close to their long-term mean."

Barring and von Storch thus concluded their paper by stating that their storminess proxies "show no indication of a long-term robust change towards a more vigorous storm climate." In fact, during "the entire historical period," in their words, storminess was "remarkably stable, with no systematic change and little transient variability." Hence, we can conclude that for much of Sweden, at least, there was no warming-induced increase in windstorms over the entire transitional period between the Little Ice Age and the Modern Warm Period, which suggests there is little reason to believe that this non-trend would change with any further warming of the globe, in stark contradiction of what most climate alarmists continually claim will occur.

Returning to where we began our review of European storminess, and to some of the same researchers, we encounter the study of Dawson et al. (2004b), who examined the sedimentary characteristics of a series of Late Holocene coastal windstorm deposits found on the Scottish Outer Hebrides, an island chain that extends across the latitudinal range 56-58°N. These deposits form part of the landward edges of coastal sand accumulations that are intercalated with peat, the radiocarbon dating of which was used to construct a local chronology of the windstorms. This work revealed that "the majority of the sand units were produced during episodes of climate deterioration both prior to and after the well-known period of Medieval warmth." The researchers also say "the episodes of sand blow indicated by the deposits may reflect periods of increased cyclogenesis in the Atlantic associated with increased sea ice cover and an increase in the thermal gradient across the North Atlantic region." In addition, they report that "dated inferred sand drift episodes across Europe show synchroneity with increased sand mobilization in SW France, NE England, SW Ireland and the Outer Hebrides, implying a regional response to storminess with increased sand invasion during the cool periods of the Little Ice Age," citing the corroborative studies of Lamb (1995), Wintle et al. (1998), Gilbertson et al. (1999) and Wilson et al. (2001). Throughout a vast portion of the North Atlantic Ocean and adjacent Europe, therefore, storminess and wind strength appear to actually have been inversely related to mean global air temperature over most of the past two millennia, with the most frequent and intense events occurring both prior to and following the Medieval Warm Period. Consequently, the climate-alarmist claim that Europe will experience more intense and frequent windstorms if air temperatures continue to rise fails to resonate with reality.

Last of all, we come to the study of Dawson et al. (2004a), who examined 120- to 225-year records of gale-days per year from five locations scattered across Scotland, northwest Ireland and Iceland, which they compared with a much longer 2000-year record for the same general region. In doing so, they found that four of the five century-scale records showed a greater frequency of storminess in the cooler 1800s and early 1900s than throughout the remainder of the warmer 20th century. In addition, they report that "considered over the last ca. 2000 years, it would appear that winter storminess and climate-driven coastal erosion was at a minimum during the Medieval Warm Period," which again is just the opposite of what climate alarmists typically predict, i.e., more storminess with warmer temperatures.

In conclusion, as the earth has recovered from the global chill of the Little Ice Age, there appears to have been no significant increase in either the frequency or intensity of stormy weather in Europe. In fact, most studies suggest just the opposite. These observations - coupled with the fact that storminess in most other parts of the planet also decreased over this period (see the other regions of the earth treated under Storms in our Subject Index) - suggest there is no real-world/data-driven reason to believe that storms would necessarily get any worse or become more frequent if the earth were to warm somewhat more in the future.

References
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