Causes of climate change over the past 1000 years

Science

Volumn 289, Issue 5477, 2000, Pages 270-277

  Crowley, Thomas J ^a  

^a TEXAS A AND M UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

CLIMATE CHANGE; GLOBAL WARMING; GREENHOUSE GAS; PALEOCLIMATE; SOLAR RADIATION; TIME SERIES ANALYSIS; VOLCANISM;

ANTARCTICA; ARTICLE; CLIMATE; CORRELATION FUNCTION; GREENHOUSE EFFECT; MODEL; PRIORITY JOURNAL; STRATOSPHERE; TEMPERATURE;

EID: 0034647920     PISSN: 00368075     EISSN: None     Source Type: Journal    
DOI: 10.1126/science.289.5477.270     Document Type: Article

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89. 18O variations in the GISP2 and Dye3 Greenland ice cores and in a winter sea ice record from Iceland [P. Bergthorsson, Jokull 19, 94 (1969); W. Dansgaard et al., in Greenland Ice Core: Geophysics, Geochemistry, and the Environment, C. C. Langway et al., Eds. (American Geophysical Union, Washington, DC, 1985), pp. 71-76; M. Stuiver, P. Grootes, T. Braziunas, Quat. Res. 44, 341 (1995)].
90. 18O variations in the GISP2 and Dye3 Greenland ice cores and in a winter sea ice record from Iceland [P. Bergthorsson, Jokull 19, 94 (1969); W. Dansgaard et al., in Greenland Ice Core: Geophysics, Geochemistry, and the Environment, C. C. Langway et al., Eds. (American Geophysical Union, Washington, DC, 1985), pp. 71-76; M. Stuiver, P. Grootes, T. Braziunas, Quat. Res. 44, 341 (1995)].
91. A. L. Berger, Quat. Res. 9, 139 (1978).
92. A seasonal two-dimensional EBM [W. T. Hyde, T. J. Crowley, K.-Y. Kim, G. R. North, J. Clim. 2, 864 (1989)] actually yields a very slight warming (0.006°C) over the past 1000 years, because perihelion is now about 2 weeks closer to the Northern Hemisphere summer solstice (it coincided with the winter solstice about 900 years ago). The EBM has a sensitivity comparable to many GCMs [T. J. Crowley, S. K. Baum, W. T. Hyde, J. Geophys. Res. 96, 9217 (1991)]. A nonlinear version of this model [W. T. Hyde, K.-Y. Kim, T. J. Crowley, G. R. North, J. Geophys. Res. 95, 18653 (1990)] indicates that snow/ice feedback would increase the sensitivity of the calculated response by about 25%.
93. A seasonal two-dimensional EBM [W. T. Hyde, T. J. Crowley, K.-Y. Kim, G. R. North, J. Clim. 2, 864 (1989)] actually yields a very slight warming (0.006°C) over the past 1000 years, because perihelion is now about 2 weeks closer to the Northern Hemisphere summer solstice (it coincided with the winter solstice about 900 years ago). The EBM has a sensitivity comparable to many GCMs [T. J. Crowley, S. K. Baum, W. T. Hyde, J. Geophys. Res. 96, 9217 (1991)]. A nonlinear version of this model [W. T. Hyde, K.-Y. Kim, T. J. Crowley, G. R. North, J. Geophys. Res. 95, 18653 (1990)] indicates that snow/ice feedback would increase the sensitivity of the calculated response by about 25%.
94. A seasonal two-dimensional EBM [W. T. Hyde, T. J. Crowley, K.-Y. Kim, G. R. North, J. Clim. 2, 864 (1989)] actually yields a very slight warming (0.006°C) over the past 1000 years, because perihelion is now about 2 weeks closer to the Northern Hemisphere summer solstice (it coincided with the winter solstice about 900 years ago). The EBM has a sensitivity comparable to many GCMs [T. J. Crowley, S. K. Baum, W. T. Hyde, J. Geophys. Res. 96, 9217 (1991)]. A nonlinear version of this model [W. T. Hyde, K.-Y. Kim, T. J. Crowley, G. R. North, J. Geophys. Res. 95, 18653 (1990)] indicates that snow/ice feedback would increase the sensitivity of the calculated response by about 25%.
95. Climate Change 1992: The Supplementary Report to the IPCC Scientific Assessment, J. T. Houghton, B. A. Callendar, S. K. Varney, Eds. (Cambridge Univ. Press, Cambridge, 1992).
96. Supported by NOAA grant NA96GP0415 and by a separate NOAA/DOE grant through Battelle/Pacific Northwest Laboratories. I thank E. Bard, S. Baum, M. Collins, G. Hegerl, W. Hyde, P. Jones, K.-Y. Kim, J. Lean, T. Lowery, M. MacCracken, M. Mann, G. North, H. Oerlemans, W. F. Ruddiman, M. Stuiver, R. Voss, and the reviewers for comments and/or assistance.