Glacial/Interglacial temperature signal in 2 km deep borehole Litoměřice, Czechia

Litoměřice borehole located in the Lowland of the Northern Czechia was drilled in 2007 to the depth of 2 km and repeatedly logged in the period 2007−2020. The analysis of the obtained data enabled us to reconstruct the temperature-depth record undisturbed by the drilling and to recognize a robust past climate signal. Whereas this signal is hidden by the temperature gradient variations caused by heterogeneous thermal properties of the sedimentary/volcanic rock strata in the uppermost 950 m, below this depth the temperature-depth profile clearly indicates a warming at the end of the last glacial. Numerical solution of the transient heat conduction equation shows that the temperature gradient increase by about 3 K/km observed in the homogenous mica schist section between 1000−1500 m depth is consistent with the ground surface temperature warming of about 10 K. The numerical simulations also suggest that the permafrost occurrence, at least in the coldest periods of the last glacial, was highly probable in the Central European lowlands.