What was done
The authors analyzed long-term sea level data from several coastal stations in northwest Europe for trends and variations related to storminess there over the past century.

What was learned
"Although the analysis results show considerable natural variability on relatively short (decadal) time scales," the authors could find "no sign of a significant increase in storminess ... over the complete time period of the data sets." In the southern portion of the North Sea, however, the natural variability was more moderate and they found "a tendency towards a weakening of the storm activity over the past 100 years," but it too was not significant.

What it means
Over the past hundred years, as the earth has warmed during its recovery from the Little Ice Age, there has been no significant increase in storminess over northwest Europe.  Hence, there is no good reason to believe that storminess there will increase if it were to warm a little more.  In addition, both the sea level observations of the last century, and their inference for the future, are in contradiction of what many parties in favor of immediate action to limit anthropogenic CO2 emissions are publicly using as leverage for their demands.