Oliver Elison Timm1, Malte Heinemann1, Axel Timmermann1,4 Fuyuki Saito3, A. Abe-Ouchi2,3

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Oliver Elison Timm1, Malte Heinemann1, Axel
Timmermann1,4 Fuyuki Saito3, A. Abe-Ouchi2,3

• Simulating the Last Glacial Termination
• Using a 3-Dimensional Coupled Climate-Ice-Sheet
  Model.

• International Pacific Research Center, University
  of Hawaii at Manoa, Honolulu, HI, USA
• 2. Center for Climate System Research, University
  of Tokyo, Kashiwa, Japan.
• 3. Research Institute for Global Change, JAMSTEC,
  Yokohama, Japan.
• 4. Dept. of Oceanography, University of Hawaii at
  Manoa, Honolulu, HI, United States.

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Oliver Elison Timm1, Malte Heinemann1, Axel
Timmermann1,4 Fuyuki Saito3, A. Abe-Ouchi2,3

• Simulating the Last Glacial Cycle
• Using a 3-Dimensional Coupled Climate-Ice-Sheet
  Model.

• International Pacific Research Center, University
  of Hawaii at Manoa, Honolulu, HI, USA
• 2. Center for Climate System Research, University
  of Tokyo, Kashiwa, Japan.
• 3. Research Institute for Global Change, JAMSTEC,
  Yokohama, Japan.
• 4. Dept. of Oceanography, University of Hawaii at
  Manoa, Honolulu, HI, United States.

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• Motivation

• Ice-sheet simulations forced with atmospheric
  boundary conditions
• Ocean-Atmosphere model simulations with external
  forcing from greenhouse gases, orbital forcing,
  and ice-sheets

• Coupled Ocean-Atmosphere- Ice-sheet simulations
  with external forcing from greenhouse gases,
  orbital forcing

Exploring what external forcings and internal
feedbacks cause glacial inceptions and
terminations
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• Motivation

Exploring what external forcings and internal
feedbacks cause glacial inceptions and
terminations
Coupled Ocean-Atmosphere- Ice-sheet simulations
with external forcing from greenhouse gases,
orbital forcing
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LOVECLIM-GLIMMERLOVECLIM-IcIES
albedo orography
Ice-sheet model GLIMMER or IcIES
ECBilt atmosphere T21, L3
VECODE vegetation
t2m,precip albedo
t2m precip
aia
air-sea fluxes
CLIO ocean sea-ice 3x3, L20
Freshwater Forcing
Rutt et al., J. Geophys. Res., 114, F02004,
2009 Abe-Ouchi et al, Clim. Past., 2007
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Ice sheet models

• GLIMMER
• (Community model developed by Hagdorn, Rutt,
  Payne, Hebeler)
• Thermomechanical 3-d model for grounded ice
• Shallow Ice Approximation
• Northern Hemisphere in polar stereographic
  projection ( approx 30N-90N domain), 148x148 grid
  (100km resolution)
• 11 sigma levels
• Daily PDD scheme
• Isostatic bedrock adjustment (3000a )
• Ice calving parameterization

• IcIES
• (Ice Sheet for Integrated Earth system Studies,
  developed by Abe-Ouchi Saito)
• Thermomechanical 3-d model for grounded ice
• Shallow Ice Approximation
• Northern Hemisphere in 1x1deg lon-lat coordinates
  (30N-89N, 360x59 grid boxes)
• 26 sigma levels
• Monthly PDD scheme
• Isostatic bedrock adjustment (5000a )
• Ice calving parameterization

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• Modeling Approach

• Asynchronous coupling
• Ocean-Atmosphere-Vegetation adjusts faster to
• ice-sheet changes than land ice to climatic
  changes

Surface elevation, albedo, ice mask
Surface elevation, albedo, ice mask
Surface temperature, precipitation (annual cycle)
Surface temperature, precipitation (annual cycle)
Note, we currently apply accelerated orbital and
greenhouse gas forcing (factor 10/20)
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External forcing Orbital changes

• Orbital parameters
• after Berger (1978)

Two orbital forcing Experiments
time
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External forcing Atmospheric Greenhouse Gas
Concentrations

• CO2 , CH4, N2O derived from Antarctic ice-cores
  (EPICA EDC)
• CO2 Luethi et al, Nature, 453, 2008.
• CH4 Loulergue et al., Nature, 453, 2008
• N2O Schilt et al, QSR., 29, 2010
• Three experiments with different
• CO2 sensitivities in LOVECLIM

Longwave radiation a ln(CO2/CO2_ref) , with
CO2_ref 356 ppmv (present day)
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Initial State Problem
Ice-sheet model IcIES forcedwith preindustrial
climatology from LOVECLIM (full forcing, not
anomaly forcing)
initial LGM
initial no ice
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Initial State Problem
Ice-sheet model IcIES forcedwith preindustrial
climatology From LOVECLIM (full forcing, not
anomaly forcing)
initial LGM
initial no ice
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LOVECLIM-GLIMMER Simulation of the
lastGlacial-Interglacial Cycle
(LOVECLIM-GLIMMER)

• Inception phase around 116kaBP
• But to weak ice-buildup
• Last Glacial Maximum
• around 20kaBP followed by
• Termination
• Termination phase extends into
• Holocene.

Note Unofficial ICE5g data for period 122-22
kaBP from the Special Bureau for
Loading http//www.sbl.statkart.no/projects/pgs/
ice_models/Peltier_ICE-5G_v1.2/
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LOVECLIM-GLIMMER Simulation of the
lastGlacial-Interglacial Cycle
(LOVECLIM-GLIMMER)
65,000 BP
115,000 BP
20,000 BP
1000 BP
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LOVECLIM-GLIMMER/IcIES sensitivity experiments

• Strong sensitivity to CO2 forcing
• Obliquity experiment
• Constant obliquity with
• present-day obliquity (23.44 deg)
• gt suppressed ice buildup
• Reduced summer insolation
• (shortwave energy) during low
• Obliquity phases important!

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Summary
Coupled Ice-sheet-Atmosphere-Ocean-Vegetation
glacial cycle experiment First successful
glacial inception and last glacial maximum
representation in LOVECLIM-GLIMMER/IcIES This
was achieved without bias correction in
temperature or precipitation fields Sensitivity
experiments highlight the strong dependence of
ice-sheet buildup on CO2 forcing and obliquity
cycles. Future improvements Include thermal and
freshwater coupling ice lt-gt ocean Study the
feedback between ice-sheets atmosphere-ocean-veget
ation circulation
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LOVECLIM-GLIMMER Simulation of the
lastGlacial-Interglacial Cycle
(LOVECLIM-GLIMMER)
Atlantic Meridional Overturning Circulation

• The coupled system generates
• millennial-scale variability.

LOVECLIM-GLIMMER LOVECLIM-IcIES
NH ice volume