The early to middle Miocene was significantly warmer than present, particularly at high latitudes. Relatively few climatic details are known about this time period compared with earlier (e.g., Cretaceous/Eocene) and later (e.g., Quaternary) intervals. In this study terrestrial proxy data are quantitatively compared with three simulations of early to middle Miocene climate (20–14 Ma) carried out using the National Center for Atmospheric Research (NCAR) Community Atmosphere Model 3.1 (CAM) and Community Land Model 3.0 (CLM). Three different meridional sea-surface temperature gradients are prescribed in order to test a range of plausible climates. Our simulations yield generally cooler and more arid conditions than indicated by the proxy record. Mean model-data discrepancies for precipitation and temperature decrease from −320 to −170 mm/yr and −0.5 to −0.4 °C, respectively, when tropical sea-surface temperatures are increased by ∼4 °C from inferred Miocene values to near modern values. The poor agreement with respect to mean annual precipitation may be attributed to the preclusion of an interactive ocean model and/or model bias.
- Received 10 September 2009.
- Revision received 1 February 2010.
- Accepted 13 February 2010.
- © Geological Society of America