Among the highly publicized changes in weather phenomena that are predicted to attend the ongoing rise in the air's CO2 content are increases in the frequency and severity of all types of storms. As a result, and in an effort to determine if these predictions have any validity, many researchers have examined historical and proxy records in an attempt to determine the validity of this hypothesis. The present review examines what has been learned about storm trends in and around the United Kingdom.
In introducing their study of the subject, Allan et al. (2009) write that an analysis of a 47-year storm database by Alexander et al. (2005) "showed an increase in the number of severe storms in the 1990s in the United Kingdom," but that "it was not possible to say with any certainty that this was either indicative of climatic change or unusual unless it was seen in a longer-term context." Hence, in an effort to provide a longer-term context to that study, Allan et al. (2009) extended the database of Alexander et al. back to 1920, almost doubling the length of the record, after which they reanalyzed the expanded dataset for the periods of boreal autumn (October, November, December) and winter (January, February, March). And in doing so, they determined that both databases exhibited peaks in storminess in the 1920s and 1990s, with boreal autumn storms being more numerous in the 1920s and winter storms being more numerous in the 1990s. The total storm numbers for each decade are plotted in the figure below; and as can be seen there, both the beginning and end decades of the record experienced nearly identical numbers of storms, demonstrating that the increasingly greater number of extreme storms that impacted the British Isles from the 1960s through the 1990s likely was not related to the global warming of that period.
Number of extreme storms impacting the British Isles in each of eight decadal periods. Created from results reported by Allan et al. (2009).
Focusing on the region of northern and northwestern Scotland, Dawson et al. (2002) 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. And additional support for this view is provided by the hypothesis of 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.
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 (Current Warm Period).
Focusing on a well-studied and data-rich 16-km-long section of the Sefton coastline of northwest England, Esteves et al. (2011) used the longest available measured datasets from the eastern Irish Sea and beyond -- including tide levels, surge heights, wind speeds and wave heights -- in a search for evidence of long-term changes in the metocean climate, after which they analyzed data defining the rate of change in shoreline position at the study site derived from a range of historical maps and aerial photographs for the period 1894-2005, with the primary aim of assessing "whether temporal changes in the rates and magnitudes of coastal erosion can be attributed to the observed trends in metocean data, and if these trends can, in turn, be associated with climate change."
According to the three UK researchers, their results "show no evidence of enhanced storminess or increases in surge heights or extreme water levels," and that "the evolution of the coastline analyzed at various temporal scales shows no strong connection with metocean trends." In addition, they report that with the exception of mean monthly wind speed (which trended slightly upwards at one site and slightly downwards at another), the available metocean data "do not indicate any statistically significant changes outside seasonal and decadal cycles."
Taking a longer perspective of the issue was Dawson et al. (2004a), 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 that "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, Dawson et al. (2004b) 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, although some studies suggest there has been a recent increase in storminess, others have shown that as the Earth has recovered from the global chill of the Little Ice Age, there has been no significant increase in either the frequency or intensity of stormy weather in and around the United Kingdom. In fact, most studies suggest just the opposite. And 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 that 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.
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Allan, R., Tett, S. and Alexander, L. 2009. Fluctuations in autumn-winter severe storms over the British Isles: 1920 to present. International Journal of Climatology 29: 357-371.
Clarke, M., Rendell, H., Tastet, J-P., Clave, B. and Masse, L. 2002. Late-Holocene sand invasion and North Atlantic storminess along the Aquitaine Coast, southwest France. The Holocene 12: 231-238.
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Wintle, A.G., Clarke, M.L., Musson, F.M., Orford, J.D. and Devoy, R.J.N. 1998. Luminescence dating of recent dune formation on Inch Spit, Dingle Bay, southwest Ireland. The Holocene 8: 331-339.
Woodworth, P.L. and Blackman, D.L. 2002. Changes in extreme high waters at Liverpool since 1768. International Journal of Climatology 22: 697-714.Last updated 16 May 2012