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Temperature (Trends -- Regional: Europe, Central) -- Summary
Was the level of late-20th century warmth in Europe truly unprecedented over the past one to two millennia, as climate alarmists claim was the case, in the mean, for the whole of the Northern Hemisphere and possibly the world?  We here review the results of several studies that provide important information relative to this question.

Jones et al. (2002) examined several 200- to 250-year European daily and monthly climatic series; and in doing so they found that the recent "relative warmth in central Europe and to a lesser extent in Central England is also seen pre-1860, although a number of recent decades are as warm."  They also report that when annual average temperatures are considered, the two series "show slight long-term warming."  However, they add that "all of the annual warming is being experienced in the cold season," and that there is a "lack of long-term warming in the 'summer' series."

The story told by these data is certainly not one of a rapidly-developing global warming catastrophe, as so many climate-alarmist politicians (ironically located in Europe) would have one believe.  In fact, given the well-established fact that the cold of winter kills far more people in Europe than does the heat of summer (see, for example, Health Effects (Temperature) in our Subject Index), the slight warming of central European winters would appear to be something to be welcomed.

In a very different type of investigation, Kinzelbach (2004) studied the shifting range of the serin, a bird that he says "was a topic of particular interest to ornithologists of the 19th and 20th century," due to "the rapid expansion of its range in historical times."  This work confirmed the earlier finding of Mayr (1926), i.e., that "north of 48°N there were no free-living populations of Serinus serinus in the 16th century."  During that period, the serin may have attempted to expand its range, but Kinzelbach says it "was halted by colder periods of the Little Ice Age after 1585, only resuming a rapid expansion at the beginning of the 19th century," after which it was "able to expand its range from the Mediterranean region throughout large areas of Central Europe within a mere 200 years."

This observation is of great significance, for it provides an important reality check on the Mann et al. (1998, 1999) hockeystick temperature record of the past millennium, which does not depict any Northern Hemispheric warming until at least 1910, a full century after the serin began its dramatic northward expansion.  The temperature history of Esper et al. (2002), on the other hand, passes the reality check with flying colors, as it depicts post-Little Ice Age Northern Hemispheric warming beginning at about the same time the serin began its northward migration, as does the temperature history of Moberg (2005).

In another unique approach to the subject, Chuine et al. (2004) used recorded dates of grape harvests in Burgundy, France to reconstruct mean spring-summer (April-August) air temperatures for that location on a yearly basis from 1370 to 2003, using "a process-based phenology model developed for the Pinot Noir grape."  The result, which they describe as being "without chronological uncertainties," is also significantly correlated with (1) mean summer air temperatures deduced from tree rings in central France, (2) the Burgundy portion of a spatial multi-proxy temperature reconstruction, as well as observed summer air temperatures in (3) Paris, (4) central England and (5) the Alps, the thermal interconnectedness of which sites gives the new temperature history an important regional significance.  So what does it show?

The most important aspect of the 633-year temperature history is the fact that it looks nothing at all like the infamous "hockeystick" temperature history of Mann et al. (1998, 1999), which underpins the climate-alarmist claim that 20th century warming is without precedent over the past thousand years.  For starters, the temperature track left by the 30-year Gaussian filter that was employed by the six scientists to smooth the data depicts but a minor 20th-century recovery from the cold temperatures of the Little Ice Age.  It should perhaps be noted, however, that the final year of the record (2003) is wildly anomalous in terms of its great spring-summer warmth; and many people have made much of that fact.  Apparently, these folks are unaware of some other important facts, namely, that one year does not a climate make and that a temperature anomaly (comprised in this case of but a single very aberrant data point) is in no way indicative of the true thermal state of the regional climate, which is more properly defined by the many closely-clustered data points that precede the aberrant point.

Perhaps the most significant difference between the temperature histories of Chuine et al. and Mann et al. is the existence of much warmer-than-present air temperatures at various times in the past in the grape-graph record (most notably from the late 1300s through the early 1400s and over a large portion of the 1600s), where there are not even any hints of elevated warmth in the hockeystick record.  In this respect, the Chuine et al. temperature history forcefully rebuts the hockeystick-derived claim of the world's climate alarmists that air temperatures of the last two decades of the 20th century were unprecedented over the past millennium and possibly over the past two millennia (Mann and Jones, 2003).

In yet one more unique study, Bartholy et al. (2004) meticulously analyzed all of the historical records amassed by Antal Rethly, a Hungarian meteorologist who collected over 14,000 historical records related to the climate of the Carpathian Basin and published several books about them (Rethly, 1962, 1970; Rethly and Simon, 1999).  In doing so, the three Hungarian scientists found that "the warm peaks of the Medieval Warm Epoch and colder climate of the Little Ice Age followed by the recovery warming period can be detected in the reconstructed temperature index time series."  In addition, they say that "a warm episode in the 16th century [was] detected in both annual- and seasonal-scale analysis of the 50-year distribution of warm and cold conditions."  Once again, therefore, we find substantial evidence for the existence of the Medieval Warm Period, which the world's climate alarmists adamantly refuse to acknowledge as ever occurring.  In addition, we have yet another indication of the existence of what we have called the "Little" Medieval Warm Period, which is beginning to look very much like another period of significantly warmer-than-current global temperatures (see Little Medieval Warm Period in our Subject Index).

The great importance of these several findings lies in the fact that if it was warmer than, or merely as warm as, it is currently during periods of the Medieval Warm Period and the "Little" Medieval Warm Period, when there was far less CO2 in the air than there is at the present time (perhaps as much as 100 ppm less), it is reasonable to believe that whatever was responsible for the warmth of those earlier times may be responsible for much of the warmth of the present era (or perhaps even all of it), which leaves rising atmospheric CO2 concentrations pretty much "out in the cold" with respect to their being responsible for earth's recovery from the inclement weather of the Little Ice Age.

References
Bartholy, J., Pongracz, R. and Molnar, Z.  2004.  Classification and analysis of past climate information based on historical documentary sources for the Carpathian Basin.  International Journal of Climatology 24: 1759-1776.

Chuine, I., Yiou, P., Viovy, N., Seguin, B., Daux, V. and Le Roy Ladurie, E.  2004.  Grape ripening as a past climate indicator.  Nature 432: 289-290.

Esper, J., Cook, E.R. and Schweingruber, F.H.  2002.  Low-frequency signals in long tree-ring chronologies for reconstructing past temperature variability.  Science 295: 2250-2253.

Jones, P.D., Briffa, K.R., Osborn, T.J., Moberg, A. and Bergstrom, H.  2002.  Relationships between circulation strength and the variability of growing-season and cold-season climate in northern and central Europe.  The Holocene 12: 643-656.

Kinzelbach, R.K.  2004.  The distribution of the serin (Serinus serinus L., 1766) in the 16th century.  Journal of Ornithology 145: 177-187.

Mann, M.E., Bradley, R.S. and Hughes, M.K.  1998.  Global-scale temperature patterns and climate forcing over the past six centuries.  Nature 392: 779-787.

Mann, M.E., Bradley, R.S. and Hughes, M.K.  1999.  Northern Hemisphere temperatures during the past millennium: Inferences, uncertainties, and limitations.  Geophysical Research Letters 26: 759-762.

Mann, M.E. and Jones, P.D.  2003.  Global surface temperatures over the past two millennia.  Geophysical Research Letters 30: 10.1029/2003GL017814.

Mayr, E.  1926.  Die Ausbreitung des Girlitz (Serinus canaria serinus L.). Ein Beitrag Zur Tiergeographie.  Journal of Ornithology 74: 571-671.

Moberg, A., Sonechkin, D.M., Holmgren, K., Datsenko, N.M. and Karlen, W.  2005.  Highly variable Northern Hemisphere temperatures reconstructed from low- and high-resolution proxy data.  Nature 433: 613-617.

Rethly, A.  1962.  Meteorological Events and Natural Disasters in Hungary until 1700.  Academic Press, Budapest, Hungary.

Rethly, A.  1970.  Meteorological Events and Natural Disasters in Hungary between 1701-1800.  Academic Press, Budapest, Hungary.

Rethly, A. and Simon, A.  1999.  Meteorological Events and Natural disasters in Hungary between 1801-1900. Vol. I-II.  Hungarian Meteorological Service, Budapest, Hungary.

Last updated 23 March 2005