What was done
The authors analyzed empirical data related to historical trends of several different types of extreme weather events and their societal impacts.

What was learned
In the words of the authors, "most measures of the economic impacts of weather and climate extremes over the past several decades reveal increasing losses."  However, they found that "trends in most related weather and climate extremes do not show comparable increases with time," thus suggesting, again in their own words, that "increasing losses are primarily due to increasing vulnerability arising from a variety of societal changes, including a growing population in higher risk coastal areas and large cities, more property subject to damage, and lifestyle and demographic changes subjecting lives and property to greater exposure."  With respect to hurricane losses that have shown a steady increase with time, for example, the authors note that "when changes in population, inflation, and wealth are considered, there is instead a downward trend."  They also note that "increasing property losses due to thunderstorm-related phenomena (winds, hail, tornadoes) are explained entirely by changes in societal factors."  In addition, they report that there is "no apparent trend in climatic drought frequency" and "no evidence of changes in the frequency of intense heat or cold waves."

What it means
In spite of all the media hype about the rising economic impact of each new year's normal share of weather and climate extremes (which many insurance companies love to hype as well), there is really nothing unusual about the weather and climate extremes themselves.  Consequently, if the globe truly is warming (for whatever reason), it must therefore be concluded, on the basis of this empirical evidence, that warming does not bring an increase in extreme weather or climate events.  And if this be true, which it is, where are all the catastrophic consequences we are regularly told must assuredly follow increasing global temperatures?  Like the emperor's new clothes, they're just not there.