Background
Climate alarmists typically claim we will see more storms in a warmer world; and a number of studies have reported increases in North Atlantic storminess over the past two decades (Jones et al., 1997; Gunther et al., 1998; Dickson et al., 2000).  Since climate alarmists claim this same period to be one of the warmest - if not the warmest - of the entire past millennium, this observation might appear to vindicate one of their major fears about the future.  The current study presents new data that come to bear upon this issue.

What was done
The authors scoured daily meteorological records of the Royal Meteorological Society held in the archives of the Society's Scottish Office in Edinburgh for Stornoway (Outer Hebrides), Lerwick (Shetland Islands), Wick (Caithness) and Fair Isle (west of the Shetland Islands), recovering all data pertaining to gale-force winds over the period 1876-1996, which enabled them to reconstruct a history of storminess for that period for northern and northwestern Scotland.

What was learned
Although North Atlantic storminess and associated North Atlantic wave heights have indeed increased over the past two decades, the authors discovered that "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 appears to be associated with a recent spate of substantial positive values of the North Atlantic Oscillation (NAO) index, the authors say "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 determine modern storminess were apparently overpowered by something even more potent, i.e., cold temperatures.  The cold temperatures, in the view of the authors, led to an expansion of sea ice in the Greenland Sea, which expanded and intensified the Greenland anticyclone, which then led to the North Atlantic cyclone track being displaced farther south.

What it means
The increased storminess and wave heights observed in the North Atlantic Ocean over the past two decades do not appear to be 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 in 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.

References
Dickson, R.R., Osborn, T.J., Hurrell, J.W., Meincke, J., Blindheim, J., Adlandsvik, B., Vinje, T., Alekseev, G. and Maslowski, W.  2000.  The Arctic Ocean response to the North Atlantic Oscillation.  Journal of Climate 13: 2671-2696.

Gunther, H., Rosenthal, W., Stawarz, M., Carretero, J.C., Gomez, M., Lozano, I., Serrano, O. and Reistad, M.  1998.  The wave climate of the northeast Atlantic over the period 1955-1994: the WASA wave hindcast.  The Global Atmosphere and Ocean System 6: 121-163.

Jones, P.D., Jonsson, T. and Wheeler, D.  1997.  Extension to the North Atlantic Oscillation using early instrumental pressure observations from Gibraltar and South-West Iceland.  International Journal of Climatology 17: 1433-1450.