CLIMATE CHANGE IN BELARUS DERIVED FROM THERMOGRAMS. V.I.Zui, Institute of Geological Sciences. National Academy of Sciences of Belarus, Minsk

Terrestrial temperatures were measured during several years both in shallow and deep boreholes in Belarus mainly for heat flow studies. The thermograms, registered under steady-state conditions in holes within all main tectonic units of the country, have sometimes both concaved and convexed shapes. They have an imprint of the ground surface paleotemperature change. Temperature fluctuations at the ground surface propagate into the ground with attenuated amplitudes and the phase shift, dependent on the depth. A few temperature versus depth diagrams without noticeable influence of ground water circulation were selected for paleoclimatic reconstructions. First estimates show that the ground surface warming 0.5–1 °C took place during the last 200-300 years. The reliability of the climatic signal, derived from thermograms, is dependent on local conditions. For instance, the groundwater circulation, the agricultural effect, resulted from the cultivation of the land, but no detailed information is available both on the history of the agricultural use of the land around studied boreholes and the velocity of water filtration in the vicinity of selected sites.