Climate change of the last 2000 years inferred from borehole temperatures: data from Hungary

Ground surface temperature (GST) history, reflecting past climate conditions in Hungary, was evaluated by analysing the excursions left on the present-day temperature–depth distribution measured by precise temperature logging in 20 boreholes. These data were used to assess climatic changes over the last two millennia. We inverted the temperature–depth data using the algorithm by Bodri and Cermak [Global Planet. Change 11 (1995) 111]. Four main episodes can be distinguished: a warm period around 0 AD, extended cold conditions in the 6–16th centuries, a general warming culminated near 1850 and the cooling since then. The verification of the GST assessment was accomplished by independent data from historical sources and the GST reconstructions in surrounding Slovakia and Slovenia. The long cold conditions in the Middle Ages and the absence of the Little Climatic Optimum seem to be generic feature of the climate in Hungary. In their more recent parts, the obtained GST histories are consistent with the meteorological records in the area.