Assessing Climate Model Simulations of Last Glacial Maximum Ocean Circulation With Carbon Isotopes

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Description

Simulations of ocean circulation during the Last Glacial Maximum (LGM; 20,000 years ago) performed by various climate modeling groups around the world for the Paleoclimate Modeling Intercomparison Project (PMIP3) will be assessed using carbon isotope measurements from the deep sea (figure). Since the PMIP3 models don't include carbon isotopes we will use the Transport Matrix Method (TMM) developed by Khatiwala et al. (2005) and Khatiwala (2007) in conjunction with models of biogeochemical and isotope cycling (Schmittner et al. 2013).

Observed δ¹³C distribution in the water column (top; Schmittner et al., 2013) and in surface (Late Holocene) sediments (second from top), in LGM sediments (third from top), and the LGM-LH difference (bottom). From Schmittner (2012; PAGES News).

Participating Modeling Groups:

CSIRO, GFDL, GISS, KCM, MIROC, MPI, MRI, NorESM-L, NCAR, IPSL

Funded by

the National Science Foundation's Marine Geology and Geophysics Program

People

Andreas Schmittner, Principle Investigator
Samar Khatiwala, PI, Oxford University, UK
Robert F. Anderson, PI, Columbia University
Chandranath Basak, Postdoctoral Researcher, Columbia University

Collaborators

R. J. Stouffer (GFDL)
J. P. Dunne (GFDL)
K. Lindsay (NCAR)
U. Mikolajewicz (MPI)
S. Murikami (MRI)
P. Heimbach (MIT)
B. Schneider (U. Kiel)
A. Legrande (GISS)
M. Kageyama (IPSL)
A. Abe-Ouchi (MIROC)
S. J. Phipps (CSIRO)
G. Lohmann (AWI)
Z. Zhang (NorESM)

Results

Analysis of the Paleoclimate Model Intercomparson Project 3 data of deep ocean circulation shows that the models all consistently simulate a stronger Atlantic Meridional Overturning Circulation (AMOC) for the LGM compared with their pre-industrial control simulations (Breeden and Schmittner, 2012; Muglia and Schmittner, 2013a) in contrast to observational estimates (Muglia and Schmittner, 2013b).

Publications

Schmittner, A., Gruber, N., Mix, A. C., Key, R. M., Tagliabue, A., and Westberry, T. K. (2013)
Biology and air-sea gas exchange controls on the distribution of carbon isotope ratios (δ¹³C) in the ocean

Biogeosciences, 10, 5793-5816, doi:10.5194/bgd-10-5793-2013.

html global synthesis of (δ¹³C) observations model code & obs

Schmittner, A. (2012)
Marine nutrient cycling - How will the ocean's capacity of biological carbon pumping change?

in Paired Perspectives on Global Change PAGES News, vol. 20, nr. 1, edited by N. R. Bondre and T. Kiefer, Past Global Changes.

pdf html

Khatiwala, S. (2007)
A computational framework for simulation of biogeochemical tracers in the ocean

Glob. Biogeochem. Cy., 21, doi: 10.1029/2007GB002923.

Khatiwala, S., M. Visbeck, and M. Cane (2005)
Accelerated simulation of passive tracers in ocean circulation models

Ocean Modell., 9, 51-69.

Presentations

Schmittner, A., Egbert, G., and Green, M. (2014)
Modeling Tidal Mixing, Past, Present, and Future (Oral)

Ocean Sciences Meeting, Feb. 27, Honolulu pdf

Schmittner, A. and Khatiwala, S. (2013)
Offline Modeling of Biogeochemical Tracers and Isotopes (Oral)

PMIP Ocean Workshop 2013, Understanding Changes since the Last Glacial Maximum, Dec. 4-6, Corvallis, Oregon, USA. pdf

Muglia, J., and Schmittner, A. (2013)
Atlantic Circulation During the Last Glacial Maximum Simulated by PMIP3 Climate Models (Poster)

PMIP Ocean Workshop 2013, Understanding Changes since the Last Glacial Maximum, Dec. 4-6, Corvallis, Oregon, USA. pdf

Muglia, J., and Schmittner, A. (2013)
Ocean Circulation During the Last Glacial Maximum Simulated by PMIP3 Climate Models (Poster)

Key Uncertainties in the Global Carbon Cycle: Perspectives across terrestrial and ocean ecosystems, Aug. 6-10, 2013, NCAR, Boulder, Colorado, USA. pdf

Breeden, M., and Schmittner, A. (2012)
Last Glacial Maximum Ocean Circulation Simulated by PMIP3 Climate Models (Poster)

American Geophysical Union Fall Meeting, Dec. 3-7, San Francisco, California, USA. pdf