129-66 Leveraging the Literature: A Paleocene-Eocene Climate Reconstruction of North America through CLAMP Analysis

Abstract:

The Paleocene and Eocene epochs are characterized by significant global warmth, with higher temperatures and more precipitation than observed today. A valuable climate proxy for estimating and reconstructing terrestrial climates is leaf physiognomy, the study of leaf characteristics and how these traits relate to environmental factors like climate. In this study, 15 dicot leaf fossil localities (including localities found in Mississippi, Louisiana, Texas, Tennessee, Washington, Oregon, California, Idaho, Nevada, Wyoming, North Dakota, and British Columbia) from published literature and one unpublished locality from the Gulf Coastal Plain of southwestern Alabama were analyzed using the Climate Leaf Analysis Multivariate Program (CLAMP). CLAMP compares fossil leaf morphology with modern vegetation samples from known climates based on a multivariable relationship between leaf physiognomy and local climate. In addition to this analysis, eight additional localities whose flora had been analyzed through CLAMP were included in the reconstruction. The resulting paleoclimate reconstructions had mean annual temperature (MAT) values ranging from 9°C to 25°C, and annual precipitation ranged from 770 mm to almost 3000 mm. The paleoclimatic conditions of the localities were spatially interpolated using GIS to create MAT and GSP surfaces. The warmest and wettest conditions were found in the Gulf Coast region of the United States, followed by the Pacific Coast. The driest, coldest conditions in the north-central United States. Both MAT and GSP differed significantly from modern values, supporting previous findings of substantially warmer and wetter conditions during the Eocene. There was an average difference of more than 5°C in MAT between the Eocene localities and their modern-day climates, and GSP was 1428 mm more on average. Future work will apply the same methods to Paleocene-aged localities to compare climate conditions and patterns between the Paleocene and Eocene.

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