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Climate Change in the Geological Past

Climate Change in the Geological Past. Keio University. August 2 nd , 2007. Nicholas Herold. The University of Sydney. Supervisors Dietmar M ü ller, John You. Discussion Outline. What, when and why: the Miocene Climatic Optimum (MCO) ‏ . The climate model.

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Climate Change in the Geological Past

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  1. Climate Change in the Geological Past Keio University. August 2nd, 2007 Nicholas Herold The University of Sydney Supervisors Dietmar Müller, John You

  2. Discussion Outline • What, when and why: the Miocene Climatic Optimum (MCO)‏. • The climate model. • Results: sensitivity to model boundary conditions • Vegetation • CO2 • Topography • Conclusions

  3. Centennial scale changes in temperature: the Hockey Stick Mann et al. (1998)‏

  4. The Ice Core Record: Vostok Wuebbles and Hayhoe (2002)‏

  5. The Geologic Record Zachos et al. (2001)‏

  6. The NCAR Climate Models • The Community Atmosphere Model (CAM3) and Community Land Model (CLM3). • Coupled to a slab ocean model. • ~3.75° x 3.75° (~416 x 416 km) resolution with 26 atmospheric layers.

  7. Model Resolution George C. Marshall Institute

  8. Model Boundary Conditions • Vegetation: from Wolfe (1985) with amendments to Australia. • Topography: adjustments to the Tibetan Plateau, Andes, Greenland and Antarctica. • 50m sea-level rise. • CO2: low (180 ppmv), medium (355 ppmv) and high (700 ppmv).

  9. Mean annual surface temperature

  10. June-July-August December-January-February

  11. June-July-August PRECIPITATION SURFACE WINDS CO2_700 – CO2_180 CO2_700 – CO2_180 mm m/s

  12. Topographic Sensitivity

  13. JJA Wind Vector Anomalies

  14. Conclusions • Realistic vegetation, topography and increased CO2 leads to a 2.7°C warming. • Vegetation and elevation did not affect global temperature significantly. • Leads us to conclude that in addition to CO2 warming was caused by deep ocean circulation, orbital parameters and/or other greenhouse gases (e.g. CH4).

  15. Future Work • Currently attempting to couple a full ocean model to the land and atmosphere models. • Implement orbital values and increased methane concentrations.

  16. Thanks to… • Dietmar Müller and John You • the Australian Research Council (ARC)‏ • the Australian Partnership for Advanced Computing (APAC) National Facility for computer time allocation.

  17. References • Mann, M.E., Bradley, R.S., Hughes, M.K., 1998. Global-scale temperature patterns and climate forcing over the past six centuries. • Wuebbles and Hayhoe, 2002. Atmospheric methane and global change. • Zachos, J., Pagani, M., Sloan, L., Thomas, E., Billups, K., 2001. Trends, Rhythms and Aberrations in Global Climate 65 Ma to Present. • National Center for Atmospheric Research (NCAR). Community Climate System Model - http://www.ccsm.ucar.edu/ • Australian Partnership for Advanced Computing (APAC). http://www.apac.edu.au/ • Wolfe J. A., 1985. Distribution of Major Vegetation Types During the Tertiary.

  18. Miocene Vegetation Distributions

  19. Modern Vegetation

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