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Understanding Pliocene Climate: The Pliocene Model Intercomparison Project
Alan Haywood, Aisling Dolan, Stephen Hunter, Daniel Hill, Ulrich Salzmann, Harry Dowsett, Bette Otto-Bliesner, Mark Chandler, Dan
Lunt, David Rowley and the PlioMIP Participants
A 400 ppm world
What has changed?
How much is yet to come?
Timescale matters
The Pliocene
CO2 Summary
• CO2 levels were also varying during the mid-Pliocene Warm Period
• Moreover, there is uncertainty in the proxy reconstructions of absolute high CO2 levels
• Thus it is necessary to consider a range of CO2 levels when modelling the ice sheets of the mid-Pliocene
• 280 to 450+ ppmv
Adapted fro m Bartoli et al. (2011)
A Geological Odyssey
VegetationBiomes
Land Ice
Sea Ice
Deep Ocean Temperature
Topography
Sea Level
Sea SurfaceTemperature
mid-Pliocene conditions
Reduced equator to pole surface temperature gradient
Enhanced poleward ocean heat transport/CO2 increase
Less land ice = higher sea level Less sea ice in the high latitudes
ENSO keeps on ticking
Warmer upwelling zones
View of mid-Pliocene environments
mid-Pliocene conditions
Reduced desertsTundra BIOME nearly absent
Poleward shift in most BIOMES
Changing view of mid-Pliocene environments
Pliocene temperature increases
PlioMIP Results
(Haywood et al., 2013 – Climate of the Past)
S ur fa c e A i r Te m pe rat ure s ( ° C ) – M ulti - M ode l M e a n
(Nature Climate Change– Salzmann et al. 2013)
To ta l P rec i p i tati o n R ate (mm/ d ay ) – Mu l ti -M o d el M ean
(Haywood et al., 2013 – Climate of the Past)
Energy balance slide
Changes in the AMOC (Zhang et al., 2013)
PlioMIP Results
Monsoons
Mean precipitation (mm/day) differences over East Asia highlighting modelled changes in the Monsoon intensity (Zhang et al., 2013 CP)
Can use PlioMIP results to tell us something about ESS
PlioMIP Results
Model Pliocene warming (K)
Climate Sensitivity
Earth System Sensitivity
ESS / CS
CCSM4 1.86 3.2 3.51 1.1COSMOS 3.60 4.1 6.77 1.7GISS-E2-R 2.12 2.7 3.98 1.5HadCM3 3.27 3.1 6.16 2.0IPSLCM5A 2.18 3.4 4.10 1.2MIROC4m 3.46 4.1 6.51 1.6MRI-CGCM 2.3 1.84 3.2 3.45 1.1NorESM-L 3.27 3.1 6.14 2.0Ensemble mean 2.66 3.36 5.01 1.5
SST Data/Model Comparison
Point-based Mean Annual SST comparison
(Dowsett et al., 2013 – Scientific Reports)
Te r re st r ia l DM C (proxy s igna l ve rsus mode l s igna l
Proxy-based temperature anomaly
Degree of data-model discordance
(anomaly versus anomaly)
(Nature Climate Change– Salzmann et al. 2013)
Pliocene Uncertainty…
Modelling Uncertainty
Structural, Parameter
Data UncertaintyAnalytical, Spatial, Temporal
Boundary Condition U
ncerta
inty
Orbita
l forci
ng, Greenhouse
gase
s,
Topogra
phy
PlioMIP Phase 2
Pliocene ti me slices
First Pliocene Time Slice (3.205 Ma) is the centre piece of PlioMIP Phase 2 which is currently under construction.
(Haywood et al., 2013 – Philosophical Transactions of the Royal Society A)
PlioMIP Phase 2
Conclusions 1. We said too much on the basis of too few models – now fixed
2. Global annual mean temperature increase of *********
3. Enhanced hydrological cycle with changes in monsoons
4. Little consistency in predictions for changes in AMOC
5. CO2 drives changes in the tropics, clear sky albedo dominates at the poles
6. Models struggle to warm high latitudes enough but…
7. ….the concept of the ‘stable Pliocene’ is obsolete
8. We need better time constraints on our syntheses of proxy data
Lectureship Available – Permanent(Marine Micropaleontology)
• Permanent position (Associate Professor)• Low teaching/admin• Within a big and growing palaeo group• Healthy start up funds• Ideal for an Early Career ScientistContact: Alan Haywood ([email protected])