Ground temperature history in Romania inferred from borehole temperature data

Abstract

Geothermal observations (temperature-depth data and thermal property measurements) from a suite of boreholes in the Romanian Carpathians area are used to infer ground surface temperature (GST) history. Temperature observations in boreholes are combined with meteorological data at nearby weather stations to test that temperature in the earth's subsurface contains a record of recent climate change. The subsurface temperature profiles are consistent with the air temperature records. The GST histories that can be extracted by inversion of perturbed temperature data from boreholes ranging in depth between 190 and 520 m cover the past 200–400 years. Results of inversion indicate for the last 150 years a cooler episode for the inner region of the Carpathian Mts. and a warmer time in the Carpathian foreland. The GST histories for this southeastern part of Europe are slightly different from those obtained in western and central Europe. These differences are consistent with the spatial variability of climatic trends.