PALEOGENE GLOBAL KÖPPEN-GEIGER CLIMATE MAPS: STAGE-LEVEL RECONSTRUCTIONS OF THE CENOZOIC GREENHOUSE

The Paleogene Period (66 to 23 Ma) was the warmest phase of the Cenozoic, characterized by high atmospheric CO₂ conditions, elevated surface temperatures, an enhanced global hydrologic cycle, and multiple, rapid hyperthermal events. It provides a unique opportunity to understand greenhouse climate systems, and an ideal natural laboratory for refining our predictions of future anthropogenic climate change. This study presents high spatial resolution, quantitative global paleoclimate interpolations of mean annual temperature, warmest month mean temperature, coldest month mean temperature, and mean annual precipitation using newly compiled temperature and precipitation proxy datasets (n > 20,000) for nine key Paleogene time slices (Danian, Selandian, Thanetian, Ypresian, Lutetian, Bartonian, Priabonian, Rupelian, Chattian). These global paleoclimate maps are generated using a geostatistical analysis employing a Markov Chain Monte Carlo algorithm, Bayesian hierarchical models, and improved paleoclimate proxy constraints, as well as a unique integration framework to produce Köppen-style paleo-maps. These proxy-based maps suggest radically different climate conditions than model-based simulations of Paleogene climate, highlighting the need for continued efforts to resolve proxy/model discrepancies. Additionally, they provide new insights into the changing spatial and temporal climate patterns during the Paleogene, especially during the transition from hothouse early Eocene conditions to cooler conditions at the end of the Oligocene.