Background
The author, with the Illinois State Water Survey at the University of Illinois, notes that high winds - excluding those associated with hurricanes, tornadoes, snowstorms, blizzards and heavy rainstorms - are one of the United States' leading types of damage-producing storms. These straight-line windstorms, as they are called, produce annual U.S. property and crop losses totaling $380 million and rank as the nation's sixth most damaging type of severe weather.

What was done
Working with data obtained from daily records of the U.S. National Weather Service made over the period 1950-2005, as well as storm information found in recent issues of Storm Data (1997, 2009), along with loss records of the property insurance industry (Property Claims Service, 2007) and catastrophe data held by the National Research Council for the period 1952-2006, Changnon calculated trends in a number of straight-line wind-related parameters over the period for which these data were available.

What was learned
Of great interest to us, in terms of whether or not the global warming of the past half-century or so has had any significant impact on straight-line windstorm frequency or ferocity, was the fact that "the distribution of losses over time showed high values in recent years, 1997-2006, and the 55-year distribution had a statistically significant upward trend over time." However, Changnon describes how a number of adjustments to loss data of the past needed to be made "to calculate a revised monetary loss value for each catastrophe so as to make it comparable to current year values, 2006 in this study." And when these adjustments were made, he reports that the 55-year time trend "was not up or down."

What it means
In light of the study's finding that "the national temporal distribution of catastrophic windstorms during 1952-2006 has a flat trend," as Changnon describes it, it is safe to say that - in the United States, at least - the global warming of the past half-century or so has had no noticeable impact on the net frequency/ferocity of straight-line windstorms.

References
Property Claims Service. 2007. The Catastrophe Record for 2006. The Fact Book 2006: Property Casualty Insurance. Insurance Information Institute, New York, New York, USA.

Storm Data. 1997. National Climatic Data Center, NOAA (Volumes 1-39).

Storm Data. 2009. National Climatic Data Center, NOAA (Volumes 37-51).