Background
Antal Rethly (1879-1975) was a meteorologist, professor and director of the National Meteorological and Earth Magnetism Institute of Hungary, who spent the greater portion of his long professional life collecting over 14,000 historical records related to the climate of the Carpathian Basin and ultimately publishing a four-volume set of books about them in the Hungarian language that contain approximately 2500 pages (Rethly, 1962, 1970; Rethly and Simon, 1999).

What was done
Bartholy et al. meticulously codified and analyzed all of the historical records collected by Rethly, noting that "in order to provide regional climate scenarios for any particular area, past climate tendencies and climatological extremes must be analyzed."

What was learned
With respect to temperature, the three Hungarian scientists report 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."

What it means
Once again, 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 existence of both of these periods of likely greater warmth than what has yet been observed during the Modern Warm Period gives the lie to the claim that current warming must be due to elevated atmospheric CO2 concentrations, which were fully 100 ppm less than what they are today during both of those earlier warm periods.

References
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.