The influence of continental ice, atmospheric CO2, and land albedo on the climate of the last glacial maximum
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The contributions of expanded continental ice, reduced atmospheric CO2, and changes in land albedo to the maintenance of the climate of the last glacial maximum (LGM) are examined. A series of experiments is performed using an atmosphere-mixed layer ocean model in which these changes in boundary conditions are incorporated either singly or in combination. The model used has been shown to produce a reasonably realistic simulation of the reduced temperature of the LGM (Manabe and Broccoli 1985b). By comparing the results from pairs of experiments, the effects of each of these environmental changes can be determined.
Expanded continental ice and reduced atmospheric CO2 are found to have a substantial impact on global mean temperature. The ice sheet effect is confined almost exclusively to the Northern Hemisphere, while lowered CO2 cools both hemispheres. Changes in land albedo over ice-free areas have only a minor thermal effect on a global basis. The reduction of CO2 content in the atmosphere is the primary contributor to the cooling of the Southern Hemisphere. The model sensitivity to both the ice sheet and CO2 effects is characterized by a high latitude amplification and a late autumn and early winter maximum.
Substantial changes in Northern Hemisphere tropospheric circulation are found in response to LGM boundary conditions during winter. An amplified flow pattern and enhanced westerlies occur in the vicinity of the North American and Eurasian ice sheets. These alterations of the tropospheric circulation are primarily the result of the ice sheet effect, with reduced CO2 contributing only a slight amplification of the ice sheet-induced pattern.
KeywordsNorthern Hemisphere Last Glacial Maximum Glacial Maximum Late Autumn Primary Contributor
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- Berlyand TG, Strokina LA, Greshnikova LE (1980) Zonal cloud distribution on the earth. Meteorol Gidrol 3: 15–23Google Scholar
- Bourke W (1974) A multi-level spectral model I. Formulation and hemispheric integrations. Mon Weather Rev 102: 687–701Google Scholar
- Broecker WS (1984) Carbon dioxide circulation through ocean and atmosphere. Nature 308: 602Google Scholar
- Chervin RM, Schneider SH (1976) On determining the statistical significance of climate experiments with general circulation models. J Atmos Sci 33: 405–412Google Scholar
- CLIMAP Project Members (1976) The surface of the ice-age earth. Science 191: 1131–1137Google Scholar
- CLIMAP Project Members (1981) Seasonal reconstructions of the earth's surface at the last glacial maximum. Geol Soc Am Map Chart Ser, MC-36Google Scholar
- Gates WL (1976a) Modeling the ice-age climate. Science 191: 1138–1144Google Scholar
- Gates WL (1976b) The numerical simulation of ice-age climate with a global general circulation model. J Atmos Sci 33: 1844–1873Google Scholar
- Gordon CT, Stern WF (1982) A description of the GFDL global spectral model. Mon Weather Rev 110: 625–644Google Scholar
- Hansen J, Lacis A, Rind D, Russell G, Stone P, Fung I, Ruedy R, Lerner J (1984) Climate sensitivity: analysis of feedback mechanisms. In: Hansen J, Takahashi T, (eds) Climate processes and climate sensitivity. Maurice Ewing Series, 5, pp 130–163Google Scholar
- Hays JD, Imbrie J, Shackleton NJ (1976) Variations in the earth's orbit: pacemaker of the ice age. Science 194: 1121–1132Google Scholar
- Kutzbach JE, Guetter PJ (1986) The influence of changing orbital parameters and surface boundary conditions on climate simulations for the past 18 000 years. J Atmos Sci 43: 1726–1759Google Scholar
- Lamb HH, Woodroffe A (1970) Atmospheric circulation during the last ice age. Quat Res 1: 29–58Google Scholar
- London J (1957) A study of atmospheric heat balance, final report. Contract AF19(122)-165 DDC, Coll of Engl, New York University, (NTIS AD 117227)Google Scholar
- Manabe S, Broccoli AJ (1985a) The influence of continental ice sheets on the climate of an ice age. J Geophys Res 90: 2167–2190Google Scholar
- Manabe S, Broccoli AJ (1985b) A comparison of climate model sensitivitiy with data from the last glacial maximum. J Atmos Sci 42: 2643–2651Google Scholar
- Manabe S, Bryan K, Spelman MJ (1979) A global ocean-atmosphere climate model with seasonal variation for future studies of climate sensitivity. Dyn Atmos Ocean 3: 393–426Google Scholar
- Manabe S, Hahn DG (1977) Simulation of the tropical climate of an ice age. J Geophys Res 82: 3889–3911Google Scholar
- Manabe S, Stouffer RJ (1980) Sensitivity of a global climate model to an increase of CO2 concentration in the atmosphere. J Geophys Res 85: 5529–5554Google Scholar
- Milankovitch M (1941) K Serb Akad Beogr Spec Publ 132, translated from German by the Israel Program for Scientific Translations, JerusalemGoogle Scholar
- Neftel A, Oeschger H, Schwander J, Stauffer B, Zumbrunn R (1982) Ice core sample measurements give atmospheric CO2 content during the past 40 000 yr. Nature 295: 200–223Google Scholar
- Shackleton NJ, Hall MA, Line J, Shuxi C (1983) Carbon isotope data in core V19-30 confirm reduced carbon dioxide concentration in the ice age atmosphere. Nature 306: 319–322Google Scholar
- Williams J, Barry RG, Washington WM (1974) Simulation of the atmospheric circulation using the NCAR global circulation model with ice age boundary conditions. J Appl Meteorol 13: 305–317Google Scholar