the role of palaeogeography in ‘mid-pliocene warmth’ (lunt et al, 2012, epsl)
DESCRIPTION
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. The role of palaeogeography in ‘mid-Pliocene warmth’ (Lunt et al, 2012, EPSL) - PowerPoint PPT PresentationTRANSCRIPT
AGU, San Francisco, 2013
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
(1) The role of palaeogeography in ‘mid-Pliocene warmth’ (Lunt et al, 2012, EPSL)
(2) How the above “could be improved”.
(3) New work
AGU, San Francisco, 2013
What is the relative contribution to mid-Pliocene warmth from:
1. CO2
2. Orography
3. Vegetation
4. Ice sheets
AGU, San Francisco, 2013
CO2 = 280 ppmv
CO2 = 400 ppmv
“PreIndustrial World”: E
“Mid-Pliocene World”: Eociv
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”: Eocv
Factorisation methodology….
AGU, San Francisco, 2013
DT=3.3oC
dTco2 = 1.6oC
dTveg = 0.3oC
dTorog = 0.7oC
dTice = 0.7oC
AGU, San Francisco, 2013
BUT….
Palaeobotanical data
Better vegetation data…
CO2 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).”
AGU, San Francisco, 2013
More realistic paleogeography study…
Orographic change: Response of the system:
Temperature
Precipitation
Foster et al, 2010
AGU, San Francisco, 2013
New paleogeography study…
Paleogeographies removed
AGU, San Francisco, 2013
New paleogeography study…
AGU, San Francisco, 2013
Temperature:
Late Pliocene minus Early Pliocene (paleogeography alone )
AGU, San Francisco, 2013
BUT, are we even asking the right question?
Foster et al, 2010
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