Czymzik, M., Dulski, P., Plessen, B., von Grafenstein, U., Naumann, R. and Brauer, A. 2010. A 450 year record of spring-summer flood layers in annually laminated sediments from Lake Ammersee (southern Germany). Water Resources Research 46: 10.1029/2009WR008360.
In the opening paragraph of their paper, the authors write that "assumptions about an increase in extreme flood events due to an intensified hydrological cycle caused by global warming are still under discussion and must be better verified," while noting that some historical flood records indicate that "flood frequencies were higher during colder periods (Knox, 1993; Glaser and Stangl, 2004), challenging the hypothesis of a correlation between the frequency of extreme floods and a warmer climate." Thus, they decided to further explore the relationship between level of warmth and degree of flooding as it may have manifested itself in southern Germany over the past 450 years.
What was done
Working in Lake Ammersee in southern Germany (48°00'N, 11°07'E), which is fed primarily by the River Ammer, Czymzik et al. retrieved two sediment cores from the deepest part of the lake in June of 2007 that they analyzed via what they describe as "a novel methodological approach that combines microfacies analyses, high-resolution element scanning (µ-XRF), stable isotope data from bulk carbonate samples (δ13Ccarb, δ18Ocarb), and X-ray diffraction (XRD) analyses (Brauer et al., 2009)."
What was learned
The six scientists determined that the flood frequency distribution over the entire 450-year time series "is not stationary but reveals maxima for colder periods of the Little Ice Age when solar activity was reduced," while reporting that "similar observations have been made in historical flood time series of the River Main, located approximately 200 km north of Ammersee (Glaser and Stangl, 2004), pointing to a wider regional significance of this finding."
What it means
As time marches on and as ever more studies of this nature are conducted in Europe and elsewhere, it is becoming ever more clear that the climate-alarmist assumption -- as Czymzik et al. describe it -- of "an increase in extreme flood events due to an intensified hydrological cycle caused by global warming" is simply not correct. In fact, it appears to be 180 degrees out of phase with reality in a substantial majority of the studies that have been conducted to date.
Brauer, A., Dulski, P., Mangili, C., Mingram, J. and Liu, J. 2009. The potential of varves in high-resolution paleolimnological studies. PAGESnews 17: 96-98.
Glaser, R. and Stangl, H. 2004. Climate and floods in Central Europe since AD 1000: Data, methods, results and consequences. Surveys in Geophysics 25: 485-510.
Knox, J.C. 1993. Large increases in flood magnitude in response to modest changes in climate. Nature 361: 430-432.Reviewed 9 February 2011