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Stormy Periods Over the Northwestern Mediterranean Sea
Reference
Sabatier, P., Dezileau, L., Colin, C., Briqueu, L., Bouchette, F., Martinez, P., Siani, G., Raynal, O. and Von Grafenstein, U. 2012. 7000 years of paleostorm activity in the NW Mediterranean Sea in response to Holocene climate events. Quaternary Research 77: 1-11.

Background
The authors write that "the Mediterranean region is one of the world's most vulnerable areas with respect to global warming," citing Giorgi (2006); and they thus consider it to be extremely important to determine what impact further temperature increases might have on the storminess of the region.

What was done
Based on sediment grain size, faunal analysis, clay mineralogy and geochemistry data, together with an associated radiocarbon chronology - all of which they obtained from a pair of piston cores extracted from the sediment bed of Pierre Blanche Lagoon in March 2006 - Sabatier et al. produced a high-resolution record of paleostorm events along the French Mediterranean coast over the past 7000 years.

What was learned
The nine French scientists, as they describe it, "recorded seven periods of increased storm activity at 6300-6100, 5650-5400, 4400-4050, 3650-3200, 2800-2600, 1950-1400, and 400-50 cal yr BP," the latter of which intervals they associate with the Little Ice Age. And they go on to state, "in contrast," that their results show that "the Medieval Climate Anomaly (1150-650 cal yr BP) was characterized by low storm activity." They further note that these changes in coastal hydrodynamics were in phase with those observed over the Eastern North Atlantic by Billeaud et al. (2009) and Sorrel et al. (2009), and that the periods of increased storminess they identified seem to correspond to periods of Holocene cooling detected in the North Atlantic by Bond et al. (1997, 2001), together with decreases in sea surface temperature reported by Berner et al. (2008), who they also say "associated this high frequency variation in sea surface temperature with 14C production rates, implying that solar-related changes are an important underlying mechanism for the observed ocean climate variability." Be that as it may (or may not), Sabatier et al. go on to state that "whatever the ultimate cause of these millennial-scale Holocene climate variations, the main decreases of sea surface temperature observed in the North Atlantic seem to be an important mechanism to explain high storm activity in the NW Mediterranean area."

What it means
Based on Sabatier et al.'s findings, together with those of the others they cite, it would appear that if earth's climate continues to warm, for whatever reason, storm activity in the Northwest Mediterranean area will likely significantly subside.

References
Berner, K.S., Koc, N., Divine, D., Godtliebsen, F. and Moros, M. 2008. A decadal-scale Holocene sea surface temperature record from the subpolar North Atlantic constructed using diatoms and statistics and its relation to other climate parameters. Paleoceanography 23: 10.1029/2006PA001339.

Billeaud, I., Tessier, B. and Lesueur, P. 2009. Impacts of the Holocene rapid climate change as recorded in a macrotidal coastal setting (Mont-Saint-Michel Bay, France). Geology 37: 1031-1034.

Bond, G., Kromer, B., Beer, J., Muscheler, R., Evans, M.N., Showers, W., Hoffmann, S., Lotti-Bond, R., Hajdas, I. and Bonani, G. 2001. Persistent solar influence on North Atlantic climate during the Holocene. Science 294: 2130-2136.

Bond, G., Showers, W., Chezebiet, M., Lotti, R., Almasi, P., deMenocal, P., Priore, P., Cullen, H., Hajdas, I. and Bonani, G. 1997. A pervasive millennial scale cycle in North-Atlantic Holocene and glacial climates. Science 278: 1257-1266.

Giorgi, F. 2006. Climate change hot-spots. Geophysical Research Letters 33: 10.1029/2006GL025734.

Sorrel, P., Tessier, B., Demory, F., Delsinne, N. and Mouaze, D. 2009. Evidence for millennial-scale climatic events in the sedimentary infilling of a macrotidal estuarine system, the Seine estuary (NW France). Quaternary Science Reviews 28: 499-516.

Reviewed 2 May 2012