Probing a Paleoclimate Model-Data Misfit in Arctic Alaska from the Cretaceous Greenhouse World

here has been a recent emphasis in climate change research on developing computer models that can simulate past and future climatic settings. These models have never been able to accurately recreate many known details of the Earth System. In particular, the late 20th-century Arctic warming and the even more pronounced polar warming during past greenhouse periods in Earth History, such as the Cretaceous, are major climate model-data misfits. The difficulty in simulating the polar warmth phenomenon might be partly attributable to uncertainties concerning the role of the hydrologic cycle in the global climate system. This failing is also exacerbated by a dearth of empirical paleoclimatic data from the Polar Regions that would better constrain our understanding of the hydrologic cycle during these time periods.;To address this problem and to better constrain the boundary conditions for climate models, this study focused on broadening the distribution of empirical oxygen isotopic data from high latitude locations of the mid-Cretaceous (Albian-Cenomanian) greenhouse world by measuring the carbon-oxygen isotopic compositions of seven pedogenic siderite paleosol horizons from the Nanushuk Formation in North Slope Alaska. Pedogenic siderite is used because it is common in the geologic record, and is widely used as a proxy for paleoprecipitation.;Sedimentologic logging and petrographic analysis of samples from the Tunalik ;This proxy record of paleoprecipitation supports earlier published results that proposed an amplified hydrologic cycle that transported more latent heat from the equator to the poles than in the present climate system. In addition to expanding the distribution of zonal empirical data from the Cretaceous Arctic, this study shows that the range of delta 18O values for Cretaceous siderite-bearing soil horizons of the North Slope, Alaska, from the Tunalik...