A 200 year mid-European air temperature record preserved in lake sediments: An extension of the delta O-18(P)-air temperature relation into the past

A detailed history of the water oxygen isotope ratios of Lake Ammersee, southern Germany, was established for the last two centuries by analyzing oxygen isotope ratios of ostracod shells from a sediment core in a three- to five-year resolution. Empirical analysis and modelling of the isotope hydrology of the lake show that the oxygen isotopic composition of the lake water is mainly controlled by the isotopic composition of local precipitation. For the last 200 years, the lake isotope record is strongly correlated to the air temperature record from Hohenpeissenberg, situated within the lake's catchment area. Thus, the mid-European relation between O-18 in precipitation and air temperature, documented for the last 20 years, can be extended over a longer time and a larger temperature range. The results provide further support for the validity of ostracod delta(18)O from Ammersee sediments as a quantitative proxy for mean annual air temperature, probably extending back to the last glaciation.