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Increasing Greenhouse Gas Concentrations and Climatic Extremes
Bohm, R. 2012. Changes of regional climate variability in central Europe during the past 250 years. The European Physical Journal Plus 127: 10.1140/epjp/i2012-12054-6.

Climate alarmists vociferously contend that greenhouse-gas-induced global warming is responsible for creating more frequent and greater extremes of weather of all types, such as extremely hot summers and excessively dry or wet seasons. But are they correct in this contention?

What was done
In an effort designed to broach this question, the author first states that "South Central Europe is among the spatially densest regions in terms of early instrumental climate data," citing Auer et al. (2007); and he goes on to state that this fact allows for successfully testing for homogeneity and developing "a larger number of very long instrumental climate time series at monthly resolution than elsewhere," - which he thus proceeds to do - noting that the resulting long time series subset of the greater alpine region provides a great potential for analyzing high frequency variability from the preindustrial (and mostly-naturally-forced) period to the "anthropogenic climate" of the past three decades. More specifically, he reports that "the unique length of the series in the region allowed for analyzing not less than 8 (for precipitations 7) discrete 30-year 'normal periods' from 1771-1800 to 1981-2010."

What was learned
As articulated by Bohm, "the overwhelming majority of seasonal and annual sub-regional variability trends is not significant." In the case of precipitation, for example, he writes that "there is a balance between small but insignificant decreases and increases of climate variability during the more than 200 years of the instrumental period," while in the case of temperature he reports that "most of the variability trends are insignificantly decreasing." And in a "special analysis" of the recent 1981-2010 period that may be considered the first "normal period" under dominant greenhouse-gas-forcing, he finds all extremes "remaining well within the range of the preceding ones under mainly natural forcing." And he notes that "in terms of insignificant deviations from the long-term mean, the recent three decades tend to be less rather than more variable [italics added]."

What it means
The study's main result - in the concluding words of the Austrian researcher at the Central Institute for Meteorology and Geodynamics in Vienna - is "the clear evidence that climate variability did rather decrease than increase over the more than two centuries of the instrumental period in the Greater Alpine Region [GAR], and that the recent 30 years of more or less pure greenhouse-gas-forced anthropogenic climate were rather less than more variable than the series of the preceding 30-year normal period." Put another way, greenhouse-gas-induced warming has not led to more frequent and/or greater extremes of either precipitation or temperature in the GAR, in clear refutation of the climate-alarmist claim as to what, in their view of the subject, should have been occurring.

Auer, I., Boehm, R., Jurkovic, A., Lipa, W., Orlik, A., Potzmann, R., Schoener, W., Ungersboeck, M., Matulla, C., Briffa, K., Jones, P., Efthymiadis, D., Brunetti, M., Nanni, T., Maugeri, M., Mercalli, L., Mestre, O., Moisselin, J.-M., Begert, M., Mueller-Westermeier, G., Kveton, V., Bochnicek, O., Stastny, P., Lapin, M., Szalai, S., Szentimrey, T., Cegnar, T., Dolinar, M., Gajic-Capka, M., Zaninovic, K. and Majstorovic, Z. 2007. HISTALP - Historical Instrumental climatological Surface Time series of the greater ALPine Region. International Journal of Climatology 27: 17-46.

Reviewed 7 November 2012