One of the many aspects of climate catastrophism that are said by climate alarmists to be sure to occur in response to CO2-induced global warming is the heaving of the world's seas beyond their normal bounds in more frequent and increasingly violent storm surges. We here investigate this claim via a brief summarization of the findings of a number of pertinent papers we have reviewed on our website, looking for evidence of the predicted changes over the course of the supposedly unprecedented warming of the past century, and particularly the past quarter-century, relative to what occurred over prior periods stretching back in time from a few decades to a few millennia.
De Lange and Gibb (2000) analyzed trends in sea level data obtained from several tide gauges located within Tauranga Harbor, New Zealand, over the period 1960-1998. In studying seasonal, interannual and decadal distributions of storm surge data, they discovered a considerable decline in the annual number of storm surge events in the latter half of the nearly four-decade-long record. A similar trend was noted in the magnitude of storm surges. In addition, maximum water levels, including tides, also declined over the past two decades.
Decadal variations in the data were linked to both the Inter-decadal Pacific Oscillation (IPO) and the El Niño-Southern Oscillation (ENSO), with La Niña events producing more storm surge days than El Niño events. In addition, wavelet analyses of annual storm surge frequency data indicated that before 1978 the frequency "was enhanced by the IPO, and subsequently it has been attenuated." Clearly, these findings are just the opposite of what climate alarmists are continually trying to scare us into believing.
Pirazzoli (2000) analyzed tide-gauge and meteorological (wind and atmospheric pressure) data for the slightly longer period of 1951-1997 along the northern portion of the Atlantic coast of France. This effort revealed that the number of atmospheric depressions (storms) and strong surge winds in this region "are becoming less frequent" and that "ongoing trends of climate variability show a decrease in the frequency and hence the gravity of coastal flooding." Because these findings, too, are just the opposite of what is being preached by radical environmentalists, Pirazzoli suggests that they should be "reassuring," especially for those concerned about coastal flooding.
Stretching out the timeframe just a bit more, Raicich (2003) analyzed 62 years of sea-level data for the period 1 July 1939 to 30 June 2001 at Trieste, in the Northern Adriatic, in an attempt to determine historical trends of positive and negative surge anomalies. This work led to the discovery that weak and moderate positive surges did 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," in Raicich's words, "as a consequence of a general weakening of the atmospheric activity," which was likewise found by Pirazzoli to be the case for Brittany.
Based on data for the somewhat longer period of 1901-1990, Wroblewski (2001) determined there was a linear increase in mean annual sea level at the southern Baltic seaport of Kolobrzeg of 12 ± 2 cm per century. Over this same period, however, there was no trend in annual sea level maxima. Two high values stood out above the rest 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. In light of the slow upward trend in mean sea level, therefore, it is extremely surprising that annual maximum sea levels due to storm surges did not likewise rise over the past century. One can only conclude that these events must have become less intense over the same time interval.
Utilizing a full century of data, Zhang et al. (2000) analyzed ten very long records of storm surges derived from hourly tide gauge measurements made along the east coast of the United States, in order to calculate indexes of count, duration and integrated intensity of surge-producing storms that provide objective, quantitative and comprehensive measures of historical storm activities in this region. The end result of their comprehensive undertaking was a demonstrable lack of "any discernible long-term secular trend in storm activity during the twentieth century," which finding, in their words, "suggests a lack of response of storminess to minor global warming along the U.S. Atlantic coast during the last 100 years."
Looking considerably further back in time, Woodworth and Blackman (2002) analyzed four discontinuous sets of high-water data from the UK's Liverpool waterfront that span 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. In doing so, they could detect no significant trends in the first two parameters over the period of study; but they found that the annual maximum surge-at-high-water actually declined, and at a rate of 0.11 ± 0.04 meters per century, which finding suggests that the winds responsible for producing high storm surges were much stronger and/or more common during the early part of the record (Little Ice Age) than during the latter part (Modern Warm Period).
Last of all, in what is by far the longest look back in time of the papers treating this subject, Nott and Hayne (2001) produced a 5000-year record of tropical cyclone frequency and intensity along a 1500-km stretch of coastline in northeastern Australia located between latitudes 13 and 24°S by (1) geologically dating and topographically surveying landform features left by surges produced by historic hurricanes and (2) running numerical models to estimate storm surge and wave heights necessary to reach the landform locations. This work revealed that several "super-cyclones" with central pressures less than 920 hPa and wind speeds in excess of 182 kilometers per hour had occurred over the past 5000 years at intervals of roughly 200 to 300 years in all parts of the region of study. The two researchers also report that the Great Barrier Reef "experienced at least five such storms over the past 200 years, with the area now occupied by Cairns experiencing two super-cyclones between 1800 and 1870." The 20th century, however, was totally devoid of such storms, "with only one such event (1899) since European settlement in the mid-nineteenth century."
In light of the findings of these several studies, it seems safe to conclude that storm surges around the world have not responded to rising temperatures in the way climate alarmists continue to claim they should, even in the face of what they describe as the most dramatic global warming of the past two millennia. Storm surges have definitely not increased in either frequency or magnitude. In the majority of cases investigated, in fact, they have actually tended to decrease.
References
De Lange, W.P. and Gibb, J.G. 2000. Seasonal, interannual, and decadal variability of storm surges at Tauranga, New Zealand. New Zealand Journal of Marine and Freshwater Research 34: 419-434.
Nott, J. and Hayne, M. 2001. High frequency of 'super-cyclones' along the Great Barrier Reef over the past 5,000 years. Nature 413: 508-512.
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. 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.
Zhang, K., Douglas, B.C. and Leatherman, S.P. 2000. Twentieth-Century storm activity along the U.S. East Coast. Journal of Climate 13: 1748-1761.
Last updated 29 March 2006