Ist das Klima von Halle (Saale) noch „normal“? Betrachtungen anhand der Temperatur- und Niederschlagsreihe von 1851 bis heute

Abstract

Döring, J.; Borg, H.: Is the climate of Halle (Saale) still “normal”? A review based on the temperature and precipitation data from 1851 until today. – Hercynia N.F. 41 (2008): 3 –21.The world-wide discussion about climate change and man-made contributions to it, which is presently going on among scientists and in the general public, raises interest in climate information on a regional scale. This is addressed here for the Halle (Saale) region. Based on local temperature and precipitation data from 1851 until today, variations and trends in these climate factors are analysed to assess, if there are signs for a change in the regional climate. As in comparable records from other parts of central Europe, the Halle data from 1851 to 2000 show a slight tendency for an increase in the mean annual air temperature and a slight tendency for a decrease in the annual precipitation. However, the coefficient of determination for both tendencies is very small, which rules them out as an indicator of future developments. For individual months, even within the same season, there is no uniform trend in air temperature or precipitation: some show a slight increase, others a slight decrease, in some there is no tendency at all. In general, the temperature and precipitation data are characterised by cyclic variations around a mean, with the cycles typically lasting several decades. Until the last year of the data considered here (2006), temperature and precipitation remained within the bounds of variation observed since 1851. This indicates that the climate in Halle shows no sign of being anything but “normal”. The 30-year periods, which are generally used to compute long-term means to which data from individual years are then compared, are unsuitable to assess variations in climate. Due to the aforementioned cyclic temperature and precipitation variations, a given 30-year reference period may fall into a relatively cold or warm and/or into a relatively dry or moist period. This is the case for the presently used reference period (1961 - 1990), which represents a comparatively cool and dry period.