Nesje et al. (2001) analyzed a sediment core from a lake in southern Norway in an attempt to determine the frequency and magnitude of prior floods in that region.  The last thousand years of the record revealed "a period of little flood activity around the Medieval period (AD 1000-1400)," which was followed by a period of extensive flood activity that was associated with the "post-Medieval climate deterioration characterized by lower air temperature, thicker and more long-lasting snow cover, and more frequent storms associated with the 'Little Ice Age'."  Hence, this particular study suggests that the post-Little Ice Age warming the earth has experienced for the last century or two - and which could well continue for some time to come - should be leading this portion of the planet into a period of less extensive flooding as opposed to the more extensive flooding that is typically predicted by climate alarmists to occur most everywhere.

Pirazzoli (2000) analyzed tide-gauge and meteorological data over the period 1951-1997 for the northern portion of the Atlantic coast of France, discovering that the number of atmospheric depressions and strong surge winds in this region "are becoming less frequent."  The data also revealed that "ongoing trends of climate variability show a decrease in the frequency and hence the gravity of coastal flooding," which is exactly what would be expected in view of the findings of Nesje et al.

Reynard et al. (2001) used a continuous flow simulation model to assess the impacts of potential climate and land use changes on flood regimes of the UK's Thames and Severn Rivers; and, as might have been expected of a model study, it predicted modest increases in the magnitudes of 50-year floods on these rivers when the climate was forced to change as predicted for various global warming scenarios.  However, when the modelers allowed forest cover to rise concomitantly, they found that this land use change "acts in the opposite direction to the climate changes and under some scenarios is large enough to fully compensate for the shifts due to climate."

To better determine what might actually happen in the real world, therefore, it is important to consider how the forested areas of the rivers' catchments might change in the future.  Two things come into play here.  First, if forests are deemed to be important carbon sinks for which countries may get sequestration credits (as envisioned in the Kyoto Protocol), and if nations begin to employ them as such, the UK government may well promote the development of new forests on much of the land in question.  Second, as the air's CO2 content continues to rise, there will be a great natural impetus for forests to expand their ranges and grow in areas where grasses now dominate the landscape (see Trees (Range Expansions) in our Subject Index).  Consequently, with man and nature both singing the same tune, so to speak, it is only logical to presume that forests will indeed expand their presence on the river catchments in question and neutralize any predicted increases in flood activity in a future high-CO2 world.

Warming itself may also help in this regard, as per the findings of Starkel (2002), who reviewed what is known about the relationship between extreme weather events and the thermal climate of Europe during the Holocene.  This review clearly demonstrated that more extreme fluvial activity was typically associated with cooler time intervals.  In recovering from one such period (the Younger Dryas), for example, temperatures in Germany and Switzerland rose by 3-5°C over several decades; and "this fast shift," in Starkel's words, "caused a rapid expansion of forest communities, [a] rise in the upper treeline and higher density of vegetation cover," which led to a "drastic" reduction in sediment delivery from slopes to river channels.

As an example of just how far out of touch with reality the world's climate alarmists are on this topic, we refer to John Hooper's 14 August 2002 article in The Guardian, where he notes that in the midst of 2002's massive flooding in Europe, Gallus Cadonau (the managing director of the Swiss Greina Foundation) called for a punitive tariff on U.S. imports to force cooperation on greenhouse gas emissions, claiming that the flooding "definitely has to do with global warming" and stating that "we must change something now."

Cadonau was joined in this sentiment by Germany's environment minister, Jurgen Trittin, who implied much the same thing when he said "if we don't want this development to get worse, then we must continue with the consistent reduction of environmentally harmful greenhouse gasses."  A thorough analysis of historical flood accounts and more recent river-flow data, however, suggests something very different, as noted by Mudelsee et al. (2003), who analyzed historical documents from the 11th century to 1850, plus subsequent water stage and daily runoff records from then until 2002, for two of the largest rivers in central Europe: the Elbe and Oder Rivers.

The team of German scientists reported that "for the past 80 to 150 years" -- which climate alarmists typically describe as a period of unprecedented global warming -- "we find a decrease in winter flood occurrence in both rivers, while summer floods show no trend, consistent with trends in extreme precipitation occurrence."  These findings clearly indicate that the strident claims of the world's Cadonaus and Trittins don't stand up to scrutiny when compared with reality.  As the world has recovered from the global chill of the Little Ice Age, flooding of the Elbe and Oder rivers has not materially changed in summer and has actually decreased in winter.  Blaming anthropogenic CO2 emissions for the European flooding of 2002 must thus have been a political ploy, for it was surely not a reasoned deduction based on scientific evidence.

Another example of similar behavior from this time period occurred on 8 and 9 September 2002, when extreme flooding of the Gardon River in southern France -- which occurred as a result of half a year's rainfall being received in approximately twenty hours -- claimed the lives of a number of people and caused much damage to towns and villages situated adjacent to its channel.  The event elicited much coverage in the press; and, in the words of Sheffer et al. (2003), "this flood is now considered by the media and professionals to be 'the largest flood on record'," which record extends all the way back to 1890.

Coincidently -- and fortunately! -- Sheffer et al. were in the midst of a study of prior floods of the Gardon River when the recent "big one" hit.  Hence, they had data spanning a much longer time period against which to compare its magnitude.  Based on their findings, they report that "the extraordinary flood of September 2002 was not the largest by any means," noting that "similar, and even larger floods have occurred several times in the recent past," with three of the five greatest floods they had identified to that point in time occurring over the period AD 1400-1800 during the Little Ice Age.  Commenting on these facts, Sheffer et al. stated that "using a longer time scale than human collective memory, paleoflood studies can put in perspective the occurrences of the extreme floods that hit Europe and other parts of the world during the summer of 2002."  And that perspective clearly shows that even greater floods occurred repeatedly during the Little Ice Age, which was the coldest period of the current interglacial.

One final study to address this subject as it applies to Europe was that of Lindstrom and Bergstrom (2004), who analyzed runoff and flood data from more than 60 discharge stations scattered throughout Sweden, some of which provide information stretching as far back in time as the early to mid 1800s, when Sweden and the world were still experiencing the cold of the Little Ice Age.  This analysis led them to discover that the last 20 years of the past century were indeed unusually wet, with a runoff anomaly of +8% compared with the century average.  But they also found that "the runoff in the 1920s was comparable to that of the two latest decades," and that "the few observation series available from the 1800s show that the runoff was even higher than recently."  What is more, they note that "flood peaks in old data are probably underestimated," which "makes it difficult to conclude that there has really been a significant increase in average flood levels," as is often claimed by climate alarmists and reported in the media.  In addition, they say that "no increased frequency of floods with a return period of 10 years or more, could be determined."

With respect to the generality of their findings, Lindstrom and Bergstrom say that conditions in Sweden "are consistent with results reported from nearby countries: e.g. Forland et al. (2000), Bering Ovesen et al. (2000), Klavins et al. (2002) and Hyvarinen (2003)," and that, "in general, it has been difficult to show any convincing evidence of an increasing magnitude of floods (e.g. Roald, 1999) in the near region, as is the case in other parts of the world (e.g. Robson et al., 1998; Lins and Slack, 1999; Douglas et al., 2000; McCabe and Wolock, 2002; Zhang et al., 2001)."

In light of this body of evidence, it is clear that for most of Europe, as well as many other parts of the world, there are simply no compelling real-world data to support the climate-alarmist claim that global warming leads to more frequent and severe flooding.  In fact, the lack of such evidence over the past century -- which is typically described by climate alarmists as having experienced an increase in global temperature that is unprecedented over the past one to two millennia -- should surely qualify as proof of the falsity of their contentions.

References
Bering Ovesen, N., Legard Iversen, H., Larsen, S., Muller-Wohlfeil, D.I. and Svendsen, L.  2000.  Afstromningsforhold i danske vandlob.  Faglig rapport fra DMU, no. 340. Miljo- og Energiministeriet.  Danmarks Miljoundersogelser, Silkeborg, Denmark.

Douglas, E.M., Vogel, R.M. and Kroll, C.N.  2000.  Trends in floods and low flows in the United States: impact of spatial correlation.  Journal of Hydrology 240: 90-105.

Forland, E., Roald, L.A., Tveito, O.E. and Hanssen-Bauer, I.  2000.  Past and future variations in climate and runoff in Norway.  DNMI Report no. 1900/00 KLIMA, Oslo, Norway.

Hyvarinen, V.  2003.  Trends and characteristics of hydrological time series in Finland.  Nordic Hydrology 34: 71-90.

Klavins, M., Briede, A., Rodinov, V., Kokorite, I. and Frisk, T.  2002.  Long-term changes of the river runoff in Latvia.  Boreal Environmental Research 7: 447-456.

Lindstrom, G. and Bergstrom, S.  2004.  Runoff trends in Sweden 1807-2002.  Hydrological Sciences Journal 49: 69-83.

Lins, H.F. and Slack, J.R.  1999.  Streamflow trends in the United States.  Geophysical Research Letters 26: 227-230.

McCabe, G.J. and Wolock, D.M.  2002.  A step increase in streamflow in the conterminous United States.  Geophysical Research Letters 29: 2185-2188.

Mudelsee, M., Borngen, M., Tetzlaff, G. and Grunewald, U.  2003.  No upward trends in the occurrence of extreme floods in central Europe.  Nature 425: 166-169.

Nesje, A., Dahl, S.O., Matthews, J.A. and Berrisford, M.S.  2001.  A ~4500-yr record of river floods obtained from a sediment core in Lake Atnsjoen, eastern Norway. Journal of Paleolimnology 25: 329-342.

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

Reynard, N.S., Prudhomme, C. and Crooks, S.M.  2001.  The flood characteristics of large UK rivers: Potential effects of changing climate and land use.  Climatic Change 48: 343-359.

Roald, L.A.  1999.  Analyse av lange flomserier.  HYDRA-rapport no. F01, NVE, Oslo, Norway.

Robson, A.J., Jones, T.K., Reed, D.W. and Bayliss, A.C.  1998.  A study of national trends and variation in UK floods.  International Journal of Climatology 18: 165-182.

Sheffer, N.A., Enzel, Y., Waldmann, N., Grodek, T. and Benito, G.  2003.  Claim of largest flood on record proves false.  EOS: Transactions, American Geophysical Union 84: 109.

Starkel, L.  2002.  Change in the frequency of extreme events as the indicator of climatic change in the Holocene (in fluvial systems).  Quaternary International 91: 25-32.

Zhang, X., Harvey, K.D., Hogg, W.D. and Yuzyk, T.R.  2001.  Trends in Canadian streamflow.  Water Resources Research 37: 987-998.