1. Modelling Ancient Earth Climate Alan Haywood School of Earth & Environment, University of Leeds With thanks to Paul Valdes, Jane Francis, Dan Lunt, Vicky Peck, Mark Williams and Harry Dowsett

2. CONTENT:  Rationale  Models and Modelling  Eocene/Oligocene - Bipolar Glaciation?  Estimates of Earth System Sensitivity - Climate Vs Earth System Sensitivity - The Pliocene - Palaeo estimates of Earth System Sensitivity

3. Motto and Philosophy Everything comes to those who wait Occam's razor: if all things are equal then the simplest solution is probably correct

4. Why? Understand climate dynamicsUnderstand climate dynamics Test Earth System ModelsTest Earth System Models

5. Where are we now?

6. Simulation of the historical or near-historical record Simulation of the historical or near-historical record Analysis of the observed record of variability Analysis of the observed record of variability Projection for the next 100 years Projection for the next 100 years Primary Research Focus in Climate Change Science Greatest Strengths Spatial and temporal character of the observations. Measurement of physical quantities that define the state of the atmosphere and ocean. Greatest Weaknesses Sense of change. Sense of the integration of the Earth System.

7. Greatest Strengths Spectacular sense of change (Furry Alligator Syndrome) True integrated system response Greatest Weaknesses Proxies rather than state variables Limited spatial and temporal resolution In contrast: A Research Focus in Earth History “The greatest weaknesses in a research focus on the modern record are the greatest strengths of Earth System History”

8. ClimateHistory

10. The Climate System

11. General Circulation Models Model needs to simulate albedo, emissivity and general circulation. Use “first principles” Newton's Laws of Motion 1 st Law of Thermodynamics Conservation of Mass and Moisture Hydrostatic Balance Ideal Gas Law

12. Components of an Earth System Model Aerosols: Dust and Sulphates Aerosols: Regional Model: High Resolution Regional Model: High Resolution Cryosphere- Lithosphere Model Model AtmosphericChemistryAtmosphericChemistry Atmospheric General Circulation Model Land Surface Hydrology Hydrology Ocean General Circulation Model Ocean Carbon Cycle Ocean Carbon Cycle Terrestrial Carbon Cycle Cycle

13. Brief history of numerical modelling

14. ATMOSPHERE LAND OCEANICESULPHUR CARBONCHEMISTRY ATMOSPHERE LAND OCEANICESULPHUR CARBON ATMOSPHERE LAND OCEANICESULPHUR ATMOSPHERE LAND OCEANICE ATMOSPHERE LAND OCEAN ATMOSPHERE LAND ATMOSPHERE 1999 1997 1992 1985 Development of Met. Office Climate Models Component models are constructed off-line and coupled in to the climate model when sufficiently developed 1960s Present 1990

15. HadCM3 GCM 20 Ocean Levels 19 Atmospheric Levels Atmospheric resolution: 3.75 by 2.5 degrees Ocean resolution :1.25 by 1.25

16. 19 levels in atmosphere 20 levels in ocean 2.5 lat 3.75 long 1.25 THE HADLEY CENTRE THIRD COUPLED MODEL - HadCM3 no flux adjustments 30km -5km

17. Bipolar Glaciation at the E/O Boundary?

18. Greenhouse to Icehouse transition Zachos et al., 2001 First permanent ice sheet on Antarctica pCO 2 decrease Sea level fall of 55-80 m CCD deepened by ~1 km/carbon cycle reorganisation Initiation of NADW Opening of tectonic gateways Biotic overturn in plants and animals >8 °C cooling in North America/ aridification of the Himalayas How much ice?

19. Fossil Cladophlebis Ferns Dickinsonia antarctica

20. 3D preserved conifer branches in concretions Araucaria araucana

21. Nothofagaceae Fossil Nothofagaceae Nothofagus cunninghamii How much ice?

22. Site 1263 ~1.2 ‰ 1 0.5 ‰ 100 kyr 2 0.7 ‰ 30 kyr ODP Site 1263 Riesselman et al. 2007 O. umbonatus image from Douglas, 1973

23. But what does it represent? How much  ice volume? How much  temperature? Observed sea level fall* Model simulation *10 m sea level fall = 0.1 ‰ 1 °C = 0.22 ‰ Modern Antarctic ice vol.* At least 3 °C? More ice? Or both?

24. Benthic  18 O = Ice growth + cooling ? In the Earliest Oligocene…. NADW formation was just beginning Antarctica was the principal source of deep water formation Cooling expected to be transmitted to deep-waters ATLANTIC PACIFIC INDIAN Late Eocene ATLANTIC PACIFIC INDIAN Early Oligocene

25. Benthic Mg/Ca suggests no cooling? Lear et al., 2000 South Atlantic DSDP Site 522 @ ~3000 m paleodepth (1 km above CCD) no change in temperature DSDP Site 522 Pacific ODP Site 1218 @ ~3800 m paleodepth (similar to CCD) ~2 °C warming ODP Site 1218 Lear et al., 2004

26. So the inevitable happens…

27. Will we find cooling at shallower sites (?) South Atlantic ODP Site 1263 Paleodepth ~ 2.1 km Paleo-lysocline ~ 3.8 km Paleo-CCD ~ 4.2 km prior to CCD deepening at E-O O Modern Atlantic estimates after Anderson and Archer, 2002 Assumptions/hopes 1.Similar CO 3 2- gradient 2. Mg/Ca response less at high CO 3 2- concentrations

28. Modelling approach Aim Predict effect of an Antarctic ice sheet on global ocean in Early Oligocene Model parameters HadCM3L 2 x pre-industrual pCO 2 Solar constant –0.3 % Paleogeography of Rupelian (Markwick et al., 2001) Vegetation cover predicted by TRIFFID

29. Quick Practice…

30. Effect of growing an East Antarctic ice sheet… Model initially run for 800 years -3.0 -2.0 -1.0 -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 1.0 2.0 3.0 Ocean temperature at 3962 m (°C) E. Oli - E. Oli Ann xboya-xboyc Ocean temperature at 5 m (°C) E. Oli - E. Oli Ann xboya-xboyc -3.0 -2.0 -1.0 -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 1.0 2.0 3.0

31. But, model did not reach equilibrium… Upper ocean integral of temperature (<300 m) ~ 0.7 °C cooling Model with modern Antarctic ice volume

32. But, model did not reach equilibrium… Lower ocean integral of temperature (>300 m) ~ 0.75 °C cooling Model with modern Antarctic ice volume

33. Model run extended to 2200 years Ocean temperature at 3962 m (°C) E. Oli - E. Oli -3.0 -2.0 -1.0 -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 1.0 2.0 3.0 Ann xboya1-xboyc1 Ocean temperature at 5 m (°C) E. Oli - E. Oli -3.0 -2.0 -1.0 -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 1.0 2.0 3.0 Ann xboya1-xboyc1

34. 2200 yr -3.0 -2.0 -1.0 -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 1.0 2.0 3.0 Surface ocean response to ice sheet Ocean temperature at 5 m (°C) E. Oli - E. Oli -3.0 -2.0 -1.0 -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 1.0 2.0 3.0 Ann xboya1-xboyc1 After 800 years O ODP Site 1263 Ocean temperature at 5 m (°C) E. Oli - E. Oli Ann xboya-xboyc After 2200 years

35. Upper ocean approaching equilibrium ~ 1 °C cooling Upper ocean integral of temperature (<300 m) Model with modern Antarctic ice volume

36. Deep ocean response to ice sheet Ocean temperature at 3962 m (°C) E. Oli - E. Oli -3.0 -2.0 -1.0 -0.8 -0.6 -0.4 -0.2 0.2 0.4 0.6 0.8 1.0 2.0 3.0 O ODP Site 1263 Ann xboya1-xboyc1 Ocean temperature at 3962 m (°C) E. Oli - E. Oli Ann xboya-xboyc After 800 years After 2200 years

37. Lower ocean approaching equilibrium? >1.3 °C cooling Lower ocean integral of temperature (>300 m) Model with modern Antarctic ice volume

38. Benthic  18 O = Ice growth + cooling How much  ice volume? How much  temperature? Observed sea level fall* Model *10 m sea level fall = 0.1 ‰ 1 °C = 0.22 ‰ Modern Antarctic ice vol.* ?

39. How much did deep waters cool? ? Upper ocean integral of temperature (<300 m)

40. Findings to date… Model predicts cooling of deep ocean in response to Antarctic glaciation in the Early Oligocene Response in surface ocean temperature is spatially heterogeneous, but at the site of 1263 the model is consistent with SST records from 1263 Deep ocean is predicted to have cooled by 0.8 °C within 2200 years of Antarctic glaciation Cooling may be significantly more by the time the model has reached equilibrium… extreme ice volumes were not a feature of the Eocene-Oligocene transition

41. The Pliocene and Earth System Sensitivity

42. Constraining Earth System sensitivity “Equilibrium climate sensitivity refers to the equilibrium change in global mean surface temperature following a doubling of the atmospheric (equivalent) CO 2 concentration (Charney sensitivity)”. Estimates based around components of the Earth system that respond quickly (atmosphere, surface ocean) and neglects feedbacks linked to changing deep ocean circulation, vegetation distribution and ice sheets, which can be referred to as Earth System Sensitivity. IPCC 2007: 2 to 4.5°C. Best estimate is 3°C. Is this supported by palaeoclimatology? How different is ESS? Climate Versus Earth System Sensitivity

43. Dowsett et al. (1999) Lisiecki & Raymo (2005) The mid-Pliocene and causes of mid- Pliocene warmth Published Mechanisms: Trace gases (Raymo et al., 1996) Ocean heat transport (Dowsett et al., 1992) Palaeogeography (Rind & Chandler, 1991) ENSO dynamics (Philander & Federov, 2003)

44. Palaeobotanical data Salzmann et al. (2008) Fission track, Parrish et al, 2007 Dowsett and Cronin (1990) Vegetation… Ice… Orography… The mid-Pliocene: a different world

45. Mid-Pliocene Control and Data/Model Comparisons Total = 3.3 o C Haywood and Valdes (2004) Salzmann et al. (2009) HadCM3

46. An Ensemble Modelling Approach (changes from the pre-industrial to mid-Pliocene) orogicevegCO 2 PlioPPPP Plio modorog MPPP Plio modorogice MMPP Mod plioco2 MMMP ModMMMM Causes of Pliocene warmth….

47. An Ensemble Modelling Approach (changes from the pre-industrial to mid-Pliocene) Be cautious of the order of change… orogicevegCO 2 PlioPPPP Plio modco2 PPPM Plio modvegco2 PPMM Mod plioorog PMMM ModMMMM

48. Relative Contribution to mid- Pliocene Warmth Total Warming = 3.3°C = 0.7˚C = 0.4˚C = 1.6˚C

49. Mid-Pliocene warmth (3.3 o C) was due to … (1)Higher CO 2 – 1.5 o C (47%) (2) Modified vegetation – 0.8 o C (26%) (3) Less ice – 0.1 o C (4%) (4) Lower orography – 0.8 o C (24%) Implications for the future… (ignoring the orographic variations) Just CO 2, temp change of 1.5 o C - Climate Sensitivity ~3 o C CO 2, veg and ice, temp change of 2.5 o C - Earth System Sensitivity ~5 o C Calculation of Earth System Sensitivity

50. Sensitivity to Boundary Condition Implementation within the GCM Total = 3.3 o C CO 2 = 1.5 o Cveg = 0.8 o Corog = 0.8 o C ice = 0.1 o C veg = 1.1 o Corog = 0.6 o CCO 2 = 1.4 o C

51. Conclusions CO 2 (~45%) Vegetation (~30%) Ice (~5%) Orography (~20%) “Earth System Sensitivity” larger than Climate Sensitivity These results need to be confirmed by other models Broader significance!? Summary