High‐Resolution Lake Deposits Record Temperature Variability During the Middle Eocene Greenhouse in Central Europe

Abstract High‐resolution continental temperature records from geological archives are crucial in order to evaluate temperature dynamics under fundamentally different climate conditions than today. Particularly the warm early to middle Eocene (∼56–40 million years ago) has become the focus of paleoclimate studies with the intention of quantifying temperatures under high atmospheric carbon dioxide ( p CO 2 ) levels. However, detailed proxy reconstructions of land temperature variability during the Eocene “greenhouse” are currently lacking for large parts of the continents. Here we present a ∼430 thousand‐year high‐resolution continental temperature record, reconstructed from terrestrial biomarkers preserved in the maar sediments of the UNESCO World Heritage Site “Messel Fossil Pit,” Germany during the earliest middle Eocene of Central Europe (∼47.7–47.2 million years ago). We found that continental temperatures ranged between ∼21 and 28°C, but shifted from a highly variable (fluctuations up to ∼5°C) temperature pattern (∼155 thousand years) toward a more constant temperature state (∼145 thousand years) through the time period covered here. The shift in temperature history was possibly associated with varying orbital configurations or the concurrent initiation of North Atlantic seaway changes. Moreover, we identified a pronounced warming at ∼47.5 million years, that coincides with negative benthic oxygen and carbon isotopic excursions in the time‐equivalent marine stacks, indicating that the maar lake recorded a previously unknown “hyperthermal‐like” global warming event.