EOCENE EQUATOR-TO-POLE SURFACE OCEAN TEMPERATURES: A SIGNIFICANT CLIMATE PROBLEM?

Eocene surface ocean paleotemperature data which illustrate a reduced equator-to-pole temperature gradient, cooler tropical sea surface temperatures, and a relatively small global temperature warming (similar to 2 degrees C) present a significant climatic enigma if the reconstructions are correct. Such a temperature distribution can be achieved through greater poleward heat transport by the ocean. However, the mechanism for a greater oceanic role is uncertain. In addition, the results from climate models for conditions of a substantially greater poleward heat transport by the oceans indicate a weak atmospheric circulation and highly seasonal continental interior climates. The weak atmospheric circulation is consistent with the record of continent-derived eolian sediment recovered in deep-sea cores. However, the Eocene paleobotanical evidence from continental interiors indicates a very mild seasonality. The lack of consistency between model results, oceanic data, and terrestrial data defines the nature of the problem of Eocene climates. The solution must involve reinterpretation of at least one major source of information.