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Exploring the Impact of Palaeogeography on Pliocene Climate Variability

This study delves into the role of palaeogeography in the Pliocene climate and identifies factors contributing to the 'mid-Pliocene warmth', proposing methodologies for improvement and key areas for further research.

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Exploring the Impact of Palaeogeography on Pliocene Climate Variability

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

  2. What is the relative contribution to mid-Pliocene warmth from: • CO2 • Orography • Vegetation • Ice sheets

  3. “PreIndustrial World”: E CO2 = 280 ppmv “Mid-Pliocene World”: Eociv CO2 = 400 ppmv

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

  5. DT=3.3oC dTco2 = 1.6oC dTorog = 0.7oC dTveg = 0.3oC dTice = 0.7oC

  6. Palaeobotanical data CO2 highly uncertain…but likely below 400ppm BUT…. Better vegetation data… 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. More realistic paleogeography study… Orographic change: Response of the system: Temperature Precipitation Foster et al, 2010

  8. New paleogeography study… Paleogeographies removed

  9. New paleogeography study…

  10. Temperature: Late Pliocene minus Early Pliocene (paleogeography alone )

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

  12. 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

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