The relative roles of CO₂ and palaeogeography in determining late Miocene climate: results from a terrestrial model–data comparison

• Main Authors: A. M. Haywood, J. T. Eronen, M. J. Pound, U. Salzmann, R. Flecker, D. J. Lunt, C. D. Bradshaw
• Format: Article
• Language: English
• Published: Copernicus Publications 2012-08-01
• Series: Climate of the Past
• Online Access: http://www.clim-past.net/8/1257/2012/cp-8-1257-2012.pdf

The late Miocene palaeorecord provides evidence for a warmer and wetter climate than that of today, and there is uncertainty in the palaeo-CO₂ record of at least 200 ppm. We present results from fully coupled atmosphere-ocean-vegetation simulations for the late Miocene that examine the relative roles of palaeogeography (topography and ice sheet geometry) and CO₂ concentration in the determination of late Miocene climate through comprehensive terrestrial model-data comparisons. Assuming that these data accurately reflect the late Miocene climate, and that the late Miocene palaeogeographic reconstruction used in the model is robust, then results indicate that: <br><br> 1. Both palaeogeography and atmospheric CO₂ contribute to the proxy-derived precipitation differences between the late Miocene and modern reference climates. However these contributions exibit synergy and so do not add linearly. <br><br> 2. The vast majority of the proxy-derived temperature differences between the late Miocene and modern reference climates can only be accounted for if we assume a palaeo-CO₂ concentration towards the higher end of the range of estimates.