Eckman (1999) utilized one of the world's longest observational sea-level records (from Stockholm, Sweden, on the Baltic Sea), which stretches back over two and a quarter centuries to 1774, to investigate long-term sea level changes and their relationship to various climatic factors, noting that "long-term changes recorded at Stockholm represent, to a very large extent, the long-term behavior of the entire Baltic Sea as well as the adjacent part of the North Sea."

Near the end of the Little Ice Age, the Stockholm record indicates sea level was in a state of equilibrium, with a mean rate of change of 0.0 mm/yr.  In fact, on the basis of other studies he reviews, Eckman concludes that "sea level changes due to northern hemisphere climate variations since 800 A.D. have probably always kept within -l.5 and +1.5 mm/yr, with an average fairly close to zero."

Interannual variability in sea-level was also investigated; and a number of interesting relationships were discovered between sea level and the persistent winter winds of the region, which have been shown to produce deviations in annual mean sea level of as much as ±100 mm from the smoothed trend of the long-term record.  Specifically, extreme low-water years were found to have persistent winter winds from the northeast, while extreme high water years were found to have persistent winter winds from the southwest.

In discussing these findings, Eckman notes "there is an understandable wish to identify a possible accelerated sea level rise due to the greenhouse effect."  However, as he points out, "this is very difficult," the main reason being, in his words, that "during a shorter time interval, say one or a few decades, an apparent acceleration (or retardation) might very well be caused by anomalous winter wind conditions."

In this regard, Eckman says that from the end of the 1700s to the beginning of the 1900s, there was a rapidly decreasing number of dominating winter winds from the northeast, which winds typically tend to reduce the sea level at Stockholm.  Consequently, the gradual disappearance of these winds should have led to a gradual increase in sea level there, which is precisely what occurred over this time period.  Then, the winter winds gradually shifted to where the dominant mode was from the southwest, which tends to promote high sea levels at Stockholm, with the net result that sea-level at Stockholm rose continuously over the entire two-century period, with a mean rate of rise of 1.0 mm/yr over the last hundred years.

In light of these observations, there would appear to be no need to invoke an inordinate amount of global warming to account for the historical increase in the rate of sea-level rise at Stockholm over the past two centuries, although some of the late 19th and early 20th century rise could well have come from the amelioration of cold Little Ice Age conditions.

In another long-term study, Woodworth and Blackman (2002) analyzed four sets of British high-water data from the Liverpool waterfront that spanned the period 1768-1999, looking for changes in annual maximum high water (tide plus surge), surge at annual maximum high water (surge component of annual maximum high water), and annual maximum surge-at-high-water.  They found there were no significant trends in the first two parameters over the period of study, but that the annual maximum surge-at-high-water had actually declined at a rate of 0.11 ± 0.04 meters per century.

The results of this study run counter to two highly-hyped climate-alarmist predictions, namely, that CO2-induced global warming should be causing an increase in sea level, and that CO2-induced global warming should be increasing the frequency and/or severity of extreme weather events.  Contrary to these predictions, the Liverpool data indicate a stable maximum sea level since 1768, while the observed decline in annual maximum surge-at-high-water over the past 232 years suggests that the winds that are responsible for producing high storm surges were stronger and/or more common during the early part of the record (the Little Ice Age) than the latter part (the Modern Warm Period).

In a somewhat similar study based on data obtained at the southern Baltic seaport of Kolobrzeg, Poland, Wroblewske (2001) determined there had been a linear increase in mean sea level of 12 ± 2 cm per century at that location over the period 1901-1990.  Over the same period, however, there was no trend in annual sea level maxima.  Two high values occurred in the 1980s, but two similar spikes occurred in the 1940s; and there were half a dozen comparable high values in the first two decades of the record.

These results are comparable to those of most other such studies that have been conducted.  Wroblewske notes, for example, that "neither in the world ocean nor in European seas (Woodworth, 1990; Gornitz and Solov, 1991; Douglas, 1992) has there been any acceleration in sea level rise in the 20th century," contrary to what climate alarmists would have one believe on the basis of what they claim to have been unprecedented warming over this period.  Their claim that global warming will intensify extreme weather is also refuted by the observation that annual maximum sea levels due to storm surges have not risen over the past century, even in the face of rising annual mean sea levels.

Bijl et al. (1999) also analyzed long-term sea level data from several coastal stations in northwest Europe for trends and variations related to storminess over the past century.  Although their analysis revealed considerable natural variability on relatively short (decadal) time scales, they could find "no sign of a significant increase in storminess ... over the complete time period of the data sets."  In the southern part of the North Sea, however, natural variability was more moderate, and they found "a tendency towards a weakening of the storm activity over the past 100 years."

Last of all, Raicich (2003) analyzed 62 years of sea-level data for the period 1 July 1939 to 30 June 2001 at Trieste on the Northern Adriatic coast.  Weak and moderate positive surges were found to not exhibit any definite trends, while strong positive surges clearly became less frequent over the period of study, even in the face of a gradually rising sea level, "presumably," as Raicich states, "as a consequence of a general weakening of the atmospheric activity," which has also been found to be the case for Brittany (Pirazzoli, 2000).  Negative anomalies, on the other hand, all became less frequent, particularly the weak and moderate ones.

In light of these several similar findings, it can safely be said that the story out of Europe is one of a modest, non-accelerating rate of rise in mean sea level over the period of time that has seen the earth emerge from the depths of the Little Ice Age.  In addition, it is clear that this period of warming has seen, if anything, a decrease in extreme storminess over the continent and the seas that surround it.

References
Bijl, W., Flather, R., de Ronde, J.G. and Schmith, T.  1999.  Changing storminess?  An analysis of long-term sea level data sets.  Climate Research 11: 161-172.

Douglas, B.C.  1992.  Global sea level acceleration.  Journal of Geophysical Research 97: 12,699-12,706.

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

Gornitz, V. and Solov, A.  1991.  Observations of long-term tide gauge records for indicators of accelerated sea level rise.  In: Schlesinger, M.E. (ed.). Greenhouse Gas-Induced Climatic Change: A Critical Appraisal of Simulations and Observations.  Elsevier, Amsterdam, pp. 347-367.

Pirazzoli, P.A.  2000.  Surges, atmospheric pressure and wind change and flooding probability on the Atlantic Coast of France.  Oceanologica Acta 23: 643-661.

Raicich, F.  2003.  Recent evolution of sea-level extremes at Trieste (Northern Adriatic).  Continental Shelf Research 23: 225-235.

Woodworth, P.L.  1990.  A search for acceleration in records of European mean sea level.  International Journal of Climatology 10: 129-143.

Woodworth, P.L. and Blackman, D.L.  2002.  Changes in extreme high waters at Liverpool since 1768.  International Journal of Climatology 22: 697-714.

Wroblewski, A.  2001.  A probabilistic approach to sea level rise up to the year 2100 at Kolobrzeg, Poland.  Climate Research 18: 25-30.