A methodology for targeting palaeo proxy data acquisition: A case study for the terrestrial late Miocene Daniel J. Lunt a,b, ⁎, Rachel Flecker a , Paul J. Valdes a , Ulrich Salzmann b , Rupert Gladstone a , Alan M. Haywood c a Bristol Research Initiative for the Dynamic Global Environment (BRIDGE), School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK b British Antarctic Survey Geological Sciences Division, High Cross, Madingley Road, Cambridge CB3 0ET, UK c School of Earth and Environment, Environment Building University of Leeds, Leeds LS2 9JT, UK ABSTRACT ARTICLE INFO Article history: Received 3 August 2007 Received in revised form 17 March 2008 Accepted 18 March 2008 Available online 7 April 2008 Editor: M.L. Delaney Keywords: late Miocene Messinian Tortonian GCM When planning the acquisition of new palaeo proxy data for reconstructing past climates, many factors influence the decision of where the proxies are to be collected. One such influence is the likelihood of recording a significant climate change relative to the modern. Another consideration, which is less often considered, is the desire to target regions in which there is significant uncertainty in numerical model predictions of past climate change. New proxy data in these regions enables a more rigorous test of model simulations, and results in better constraints on the various boundary conditions used to force the models. In this paper we present a methodology for targeting new palaeo proxy data, based on model simulations. We use the terrestrial late Miocene (11.6 to 5.3 Ma) as a case study. The late Miocene climate provides insights into future climate behavior, as it is believed to have been considerably warmer than the modern. We carry out a suite of late Miocene atmosphere-only General Circulation Model simulations, which we initially evaluate relative to an example dataset of terrestrial temperature and precipitation. In terms of targeting future data acquisition, we locate those regions in the model which exhibit the largest change in temperature and/or precipitation relative to the pre-industrial. We also locate those regions which display the largest variability between the model simulations, because new data in these regions are most likely to provide a strict test of the reliability of the model results. Among other regions, the Amazon basin, the Chad basin, central Canada, and northern India are identified as potentially useful areas to collect data. © 2008 Elsevier B.V. All rights reserved. 1. Introduction General Circulation Models (GCMs) are widely used for the prediction of future climate (e.g. IPCC, 2007). Appreciation and understanding of the uncertainties involved in such predictions requires rigorous testing of these models. This evaluation process is typically carried out in two ways: firstly, by running simulations for the present-day climate so that model output can be compared with instrumental records (e.g. Pope et al., 2000); and secondly, by simulating periods in the past where there is sufficient palaeo proxy information to permit meaningful model–data comparison (e.g. Jost et al., 2005). These processes do not validate the model in terms of proving it to be correct. Rather, they allow us to evaluate how consistent its output is when compared with observations (Wunsch, 1996). In this paper, we concentrate on the second of these methods. Historically, the methodology pursued to provide robust comparison of model results and palaeo proxy data records has been to collate large, global datasets. In addition to assessing the model simulation in geographically diverse regions, this approach also helps to alleviate the scale discrepancy between model gridboxes, typically several hundreds of kilometers across, and data derived from marine or terrestrial cores. This, combined with the need to derive directly comparable quantitative information from proxies and from climate models, means that proxy datasets that have been used to evaluate climate models robustly are largely restricted to the Quaternary (e.g. the mid-Holocene, BIOME6000, Prentice et al., 2000; the Last Glacial Maximum, MARGO, Kucera et al., 2005). However, because Quatern- ary climatic conditions were predominantly colder than modern, proxy datasets from this period provide a relatively poor test of the ability of climate models to simulate warmer periods such as those envisaged as a result of global warming (IPCC, 2007). Although there has been some recent focus on the Pliocene (e.g. PRISM2, Dowsett et al., 1999; Haywood et al., 2000a,b; Haywood et al., 2005), evaluation of model behavior under warmer conditions would additionally benefit from comparison with periods deeper in the past such as the Miocene, Eocene and Cretaceous. Model–data intercomparisons have Earth and Planetary Science Letters 271 (2008) 53–62 ⁎ Corresponding author. Bristol Research Initiative for the Dynamic Global Environ- ment (BRIDGE), School of Geographical Sciences, University of Bristol, University Road, Bristol BS8 1SS, UK. Tel.: +44117 928 8186; fax: +44117 928 7878. E-mail address: d.j.lunt@bristol.ac.uk (D.J. Lunt). 0012-821X/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.epsl.2008.03.035 Contents lists available at ScienceDirect Earth and Planetary Science Letters journal homepage: www.elsevier.com/locate/epsl