1. AGU, San Francisco, 2013 The role of palaeogeography in controlling Pliocene climate and climate variability Dan Lunt, Paul Markwick Gavin Foster, Alan Haywood, Claire Loptson, Ulrich Salzmann, Gavin Schmidt, Paul Valdes (1)The role of palaeogeography in ‘mid-Pliocene warmth’ (Lunt et al, 2012, EPSL) (2)How the above “could be improved”. (3)New work

2. AGU, San Francisco, 2013 What is the relative contribution to mid-Pliocene warmth from: 1.CO 2 2.Orography 3.Vegetation 4.Ice sheets

3. AGU, San Francisco, 2013 CO2 = 280 ppmv CO2 = 400 ppmv “PreIndustrial World”: E “Mid-Pliocene World”: E ociv

4. AGU, San Francisco, 2013 “linear approach”“Stein and Alpert (1993) approach” our approach Set up a number of ‘hybrid’ simulations…. e.g. “Mid-Pliocene World but with pre-industrial ice”: E ocv Factorisation methodology….

5. AGU, San Francisco, 2013 DT=3.3 o C dT co2 = 1.6 o C dT veg = 0.3 o C dT orog = 0.7 o C dT ice = 0.7 o C

6. AGU, San Francisco, 2013 BUT…. Palaeobotanical data Better vegetation data… CO 2 highly uncertain…but likely below 400ppm Better palaeogeographic data IPCC (2013) statement on sea level: “Together, the evidence suggests that GMSL was above present levels at that time, but did not exceed 20 m above present (high confidence).”

7. AGU, San Francisco, 2013 More realistic paleogeography study… Orographic change: Response of the system: Temperature Precipitation Foster et al, 2010

8. AGU, San Francisco, 2013 New paleogeography study… Paleogeographies removed

9. AGU, San Francisco, 2013 New paleogeography study…

10. AGU, San Francisco, 2013 Temperature: Late Pliocene minus Early Pliocene (paleogeography alone )

11. AGU, San Francisco, 2013 BUT, are we even asking the right question? Foster et al, 2010

12. AGU, San Francisco, 2013 Conclusions  New factorisation metholodology can be used to determine relative importance of different boundary conditions  Work with old boundary conditions gives: CO2 = 50%, topo = 20%, ice = 20%, veg = 10%  Availability of new boundary conditions means this work should be revisited  Potential for paleogeography to play a role in long-term evolution of Miocene-Pliocene climate change, and timing of onset of Northern Hemisphere Glaciation  More focus on glacial Pliocene climates