THE CLIMATE RECORD INVERTED FROM BOREHOLE TEMPERATURES IN SLOVENIA

Temperature profiles from nine boreholes in Slovenia, located mostly i n the northeastern part of the country, have been studied for evidence of past climatic changes. The reconstruction of the ground surface te mperature (GST) history, based on 1-D theory of heat conduction, was a ccomplished using the functional space inversion (FSI) method. Because of the paucity of quality thermal conductivity data and because the n ature of heat conduction is such that information about GST changes de cay with the passage of time, the a-priori standard deviations of the thermal conductivity model (1 W m(-1) K-1) and measured temperature (0 .2 K) were chosen large enough, so that the GST histories older than 2 00 years are considerably smoothed and essentially merge with the long -term mean. The average GST history based on consistent results from s even boreholes starts to rise at the end of the last century. The ampl itude of the warming is about 0.6 to 0.7 K in the past 100 years. Two boreholes were rejected. The long-term mean GSTs lie between 9.4 and 1 1.1 degrees C. The mean annual air temperatures from the Ljubljana met eorological station are in good agreement with the average GST solutio n. The GST history of the past 20-30 thousand years (ka) was reconstru cted from the almost 2-km-deep Ljutomer temperature profile. The histo ry evidences climate variations during the Wurm (Weichselian) ice age: it places the glacial minimum of about 3 degrees C at 13-14 ka ago an d the postglacial maximum of 10.5 degrees C roughly at 2-3 ka ago. (C) 1998 Elsevier Science B.V. All rights reserved.