A recent paper published in Quaternary Research examines floods in the Mediterranean French Alps over the past 1400 years and finds that extreme precipitation and flooding were less common and less extreme during warm periods compared to cold periods. The authors find "a low flood frequency during the Medieval Warm Period and more frequent and more intense events during the Little Ice Age." The paper provides yet another example of real-world data disproving climate alarmist (IPCC) contentions that warming results in more extreme weather, extreme precipitation, or floods. The paper also shows that summer temperatures in southwestern Europe were warmer during the Medieval Warming Period [MWP] in comparison to the year 2000, and adds to the work of over 1000 scientists demonstrating that the global MWP was as warm or warmer than the present.
In addition, the paper shows that Total Solar Irradiance sharply increased by about 1 Wm-2 throughout most of the 20th century, dwarfing the alleged effect of CO2 during the 20th century [allegedly about 0.35 Wm-2 per the IPCC formula].
From the latest NIPCC Report:
Paleofloods of the Mediterranean French Alps
|Graph from the poster presentation of the same paper shows flooding was more frequent and extreme during the Little Ice Age|
Introducing their work, Wilhelm et al. (2012) say that "mountain-river floods triggered by extreme precipitation events can cause substantial human and economic losses (Gaume et al., 2009)," adding that "global warming is expected to lead to an increase in the frequency and/or intensity of such events," citing the IPCC (2007), "especially in the Mediterranean region (Giorgi and Lionello, 2008)." They then proceed to conduct a historical examination of floods in the French Alps.
Working at Lake Allos (44°14'N, 6°42'35" E) - a 1-km-long by 700-m-wide high-altitude lake in the French Alps - Wilhelm et al. carried out a coupled bathymetric and seismic survey of the lake's sediment infill, analyzing three sediment cores for grain size, geochemical composition, total organic carbon content, and pollen content and identity; while small-size vegetal macro-remains (pine needles, buds, twigs and leaves) were sampled at the base of the flood deposits and used for AMS 14C analysis, which was conducted at France's LMC14 carbon-dating laboratory. And although acknowledging the complicating fact that "changes in vegetation and/or land-use can modify soil stability/erodibility," they report that "the size of the coarsest sediment fraction still reflects stream flow velocity," citing Beierle et al. (2002) and Francus et al. (2002).
In further discussing their methodology, the thirteen French scientists report that some 160 graded layers of sedimentary deposits over the last 1400 years were compared with records of historic floods; and they indicate that these comparisons "support the interpretation of flood deposits and suggest that most recorded flood events are the result of intense meso-scale precipitation events." And they make a point of noting that the temporal history of these deposits reveals "a low flood frequency during the Medieval Warm Period and more frequent and more intense events during the Little Ice Age."
Once again, we have another example of climate-alarmist (IPCC) contentions widely missing the mark when it comes to predicting which temperature extreme - hot or cold - produces both more frequent and more intense precipitation events, as well as the flooding that accompanies them.
Wilhelm, B., Arnaud, F., Sabatier, P., Crouzet, C., Brisset, E., Chaumillon, E., Disnar, J.-R., Guiter, F., Malet, E., Reyss, J.-L., Tachikawa, K., Bard, E. and Delannoy, J.-J. 2012. 1400 years of extreme precipitation patterns over the Mediterranean French Alps and possible forcing mechanisms. Quaternary Research 78: 1-12.
Beierle, B.D., Lamoureux, S.F., Cockburn, J.M.H. and Spooner, I. 2002. A new method for visualizing sediment particle size distributions. Journal of Paleolimnology 27: 279-283.
Francus, P., Bradley, R.S., Abbott, M.B., Patridge, W. and Keimig, F. 2002. Paleoclimate studies of minerogenic sediments using annually resolved textural parameters.Geophysical Research Letters 29: 10.1029/2002GL015082.
Gaume, E., Bain, V., Bernardara, P., Newinger, O., Barbuc, M., Bateman, A., Blaskovicova, L., Bloschl, G., Borga, M., Dumitrescu, A., Daliakopoulos, I., Garcia, J., Irimescu, A., Kohnova, S., Koutroulis, A., Marchi, L., Matreata, S., Medina, V., Preciso, E., Sempere-Torres, D., Stancalie, G., Szolgay, J., Tsanis, I., Velasco, D. and Viglione, A. 2009. A compilation of data on European flash floods. Journal of Hydrology 367: 70-78.
Giorgi, F. and Lionello, P. 2008. Climate change projections for the Mediterranean region. Global and Planetary Change 63: 90-104.
IPCC. 2007. Climate Change 2007: The Physical Science Basis. Solomon, S., Qin, D., Manniing, M., Chen, Z., Marquis, M., Averyt, K.B., Tignor, M. and Miller, H.L. (Eds.), Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom.