McPhaden and Zhang (2002) studied surface winds over the Pacific Ocean and the currents they produce in the water below that flow outward from the equator and eventually sink and flow back from both hemispheres to meet and rise near the equator.  Over the period 1950-1999, they discovered that this overturning circulation of the ocean "has been slowing down since the 1970s, causing a decrease in upwelling of about 25% in an equatorial strip between 9°N and 9°S."  As for the reason for the decrease in wind speeds, the scientists indicate the gradual decline may possibly have been caused by global warming - which is just the opposite of what climate alarmists say should happen - but they also note that natural variability may just as easily have been the cause of what they observed.

In a very different part of the world, Siegismund and Schrum (2001) investigated wind speed characteristics over the North Sea for the period 1958-1997, finding that "the annual mean wind speed for the North Sea shows a rising trend of ~10% during the last 40 years," in harmony with what climate alarmists typically predict.  In addition, they determined that "since the early 1970s 'strong wind' events are more frequent than in the 1960s," also in harmony with climate-alarmist predictions.  As for the cause of these phenomena, however, the researchers say their data "may suggest an anthropogenic origin, but this hypothesis can neither be supported nor disproved by analyzing such short time series."

In order to gain a better understanding of the relationship - if any - that may exist between global air temperature and wind speed, we clearly need to look at longer time scales.  Hence, we turn to the study of Slonosky et al. (2000), who analyzed atmospheric surface pressure data from 51 stations located throughout Europe and the eastern North Atlantic over the period 1774-1995; and we find, according to these investigators, that atmospheric circulation over Europe was "considerably more variable, with more extreme values in the late 18th and early 19th centuries than in the 20th century."  This longer view of history thus suggests that greater planetary warmth tends to produce less extreme weather and lower wind speeds.

Taking an even longer look at history, Clarke et al. (2002) used an infrared stimulated luminescence technique to date sands from dunes in the Aquitaine region of southwest France.  From their measurements they identified three main phases of wind-induced dune formation: 4000-3000 years ago during the long cold interval that preceded the Roman Warm Period, 1300-900 years ago during the early to middle Medieval Warm Period, but during what they describe as its cooler periods, and 550-250 years ago during the Little Ice Age, again during what they call its cooler periods.  In addition, a search of the literature allowed the scientists to identify similar massive wind-induced movements of sand in England, Scotland, Denmark, Portugal and the Netherlands during these same times of relative coolness.  For the most recent of these cool periods, they also note the existence of voluminous historical records that describe many severe North Atlantic wind storms.  Taken together, these observations suggest that the cool nodes of earth's millennial-scale climatic oscillation are much more prone to high wind conditions than are its warm nodes.

What are the implications of these observations?  Although there likely are several, we make special note of only two.

Wilkening et al. (2000) present a brief overview of what we know about the long-range aerial transport of biologically significant materials, focusing upon the transport of dust and various pollutants from Eurasia.  These substances can radically affect all sorts of life forms, and they are spread across the entire face of the planet by currents of air that encircle the globe.  With the increase in air temperature the earth has experienced during its recovery from the global chill of the Little Ice Age, therefore, we could well be experiencing less extensive transport of these materials than what was the case a couple of centuries ago, based on the observations of the prior two papers.  With the growth of both population and industrialization over the same time period, however, the negative consequences of this phenomenon are probably still on the rise.

On another front, Ekman (1999) utilized sea level data from Stockholm, Sweden, that stretched back in time over two and a quarter centuries to 1774, to investigate long-term trends in the levels of the Baltic and North Seas, as well as the relationships of these trends to various climatic factors.  Throughout the 1800s, they determined there had been a rapidly decreasing number of dominating winter winds from the northeast.  Since such winds typically tend to reduce sea levels at Stockholm, this regime shift led to a gradual increase in the rate of rise of sea level there.  Subsequently, the winter winds gradually shifted to where the dominant airflow was from the southwest.  Since winds from this direction tend to promote high sea levels at Stockholm, the rate of rise in sea level there continued to increase.  The net result of these wind regime changes was thus a continual increase in the rate of rise of sea level at Stockholm over the entire two-century period, resulting in a mean sea level rise of 1.0 mm/year over the 20th century.  Hence, as the world transitioned from the Little Ice Age to the Modern Warm Period, sea levels around Stockholm rose, not from the melting of polar ice, but from a systematic shifting of wind direction.

Finally, we report on the study of Cerveny and Balling (1998), who detected a weekly cycle in Atlantic tropical cyclone wind speed from data spanning the period 1946 to 1996.  Because no natural weather phenomena are known to have weekly cycles, what they observed must have been the result of anthropogenic activity; and the two scientists suggest that increased weekday particulate pollution from vehicular traffic and industrial activities (relative to weekend pollution) was responsible for the cycle they observed, wherein tropical cyclone wind speeds dropped by 3.6 to 5.0 meters per second between Friday and Saturday of each week.  In addition, working with Cerveny and Balling's data subsequent to the appearance of their publication, we demonstrated in our Journal Review of their paper that there was a 4.7 meters per second decline in tropical cyclone mean wind speed over the period 1958 to 1983, which was also likely the result of increasing "extensive regional pollution advection into the Atlantic," as they put it, but in this case over the course of several years.

To briefly summarize these several findings, the gradual warming of the globe over the past two centuries has probably reduced wind speeds over many portions of the planet, although there may well be regional exceptions to this general rule.  In addition, the increasing pollution of the global atmosphere over this period may also have reduced the wind speeds of certain tropical cyclones.  These changes in wind speed have implications for a host of other phenomena, ranging from reconstructions of true sea level histories to both positive and negative impacts on the health of terrestrial and aquatic ecosystems.

References
Cerveny, R.S. and Balling Jr., R.C.  1998.  Weekly cycles of air pollutants, precipitation and tropical cyclones in the coastal NW Atlantic region.  Nature 394: 561-563.

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.

Ekman, M.  1999.  Climate changes detected through the world's longest sea level series.  Global and Planetary Change 21: 215-224.

McPhaden, M.J. and Zhang, D.  2002.  Slowdown of the meridional overturning circulation in the upper Pacific Ocean.  Nature 415: 603-608.

Siegismund, F. and Schrum, C.  2001.  Decadal changes in the wind forcing over the North Sea.  Climate Research 18: 39-45.

Slonosky, V.C., Jones, P.D. and Davies, T.D.  2000.  Variability of the surface atmospheric circulation over Europe, 1774-1995.  International Journal of Climatology 20: 1875-1897.

Wilkening, K.E., Barrie, L.A. and Engle, M.  2000.  Trans-Pacific air pollution.  Science 290: 65-67.