Nature 360, 573 - 576 (10 December 1992); doi:10.1038/360573a0

Deriving global climate sensitivity from palaeoclimate reconstructions

Martin I. Hoffert^* & Curt Covey^†

^* Earth Systems Group, Department of Applied Science, New York University, New York 10003, USA
^† Lawrence Livermore National Laboratory, Livermore, California 94551, USA

To assess the future impact of anthropogenic greenhouse gases on global climate, we need a reliable estimate of the sensitivity of the Earth's climate to changes in radiative forcing. Climate sensitivity is conventionally defined as the equilibrium surface temperature increase for carbon dioxide doubling, T _2x. Uncertainties in cloud processes spread general circulation model (GCM) estimates of this parameter over the range 1.5< T _2x <4.5°C (refs 1, 2). An alternative to model-based estimates is in principle available from the reconstruction of past climates^3–6, which implicitly includes cloud feedback. Here we retrieve the sensitivity of two palaeoclimates, one colder and one warmer than present, by independently reconstructing both the equilibrium surface tem-perature change and the radiative forcing. Our results yield T _2x = 2.3 0.9 °C. This range is comparable with estimates from GCMs and inferences from recent temperature observations and ocean models^7,8. Future application of the method to additional climates in the geological record might constrain climate sensitivity enough to narrow the model uncertainties of global warming predictions.

References

1.	Cess, R. D. et al. Science 245, 513−516 (1989). | ISI |
2.	Houghton, J. T. et al. (eds) Climate Change: The IPCC Scientific Assessment (Cambridge Univ. Press, 1990).
3.	Lorius, C. et al. Nature 347, 139−145 (1990). | Article | ISI | ChemPort |
4.	Hansen, J. E. & Lacis, A. A. Nature 346, 713−719 (1990). | Article | ChemPort |
5.	MacCracken, M. C. et al. (eds) Prospects for Future Climate: A Special US/USSR Report on Climate and Climate Change (Lewis, Chelsea, Michigan, 1990).
6.	Budyko, M. I. & Izrael, Y. A. Anthropogenic Climate Change, 277−318 (Univ. of Arizona Press, Tucson, 1991).
7.	Wigley, T. M. L. & Raper, S. C. B. in Climate Change: Science, Impacts and Policy (eds Jäger. J. & Ferguson, H. L.) 231−242 (Cambridge Univ. Press, 1992).
8.	Schlesinger, M. E. & Jiang, X. Nature 350, 219−221 (1991). | Article |
9.	Shine, K. P. et al. in Climate Change: The IPCC Scientific Assessment (eds Houghton, J. T., Jenkins, G. & Ephraums, J. J.) 41−68 (Cambridge Univ. Press, 1990).
10.	Mitchell, J. F. B. Rev. Geophys. 27, 115−139 (1989).
11.	Manabe, S. & Weatherland, R. T. J. atmos. Sci., 24, 241−259 (1967). | Article | ISI | ChemPort |
12.	Raval, A. & Ramanathan, V. Nature 342, 758−761 (1989). | Article |
13.	Lindzen, R. S. Bull. Am. met. Soc. 71, 288−299 (1990).
14.	Hoffert, M. I. et al. J. geophys. Res. 85 (C11) 6667−6679 (1980). | ISI |
15.	Wigley, T. M. L. & Raper, S. C. B. in Climate and Sea Level Changes: Observations, Projections and Implications (eds Warrick, R. A., Barrow, E. M. & Wigley, T. M. L.) (Cambridge Univ. Press, in the press).
16.	Charlson, R. J. et al. Science 255, 423−430 (1992). | ISI | ChemPort |
17.	Wigley, T. M. L. & Raper, S. C. B. Nature 357, 293−300 (1992). | Article | ChemPort |
18.	Schlesinger, M. E., Jiang, X. & Charlson, R. J. in Climate Change and Energy Policy (eds Rosen, L. & Glasser, R.) 75−108 (American Institute of Physics, New York, 1992).
19.	Crowley, T. J. & North, G. Paleoclimatology (Oxford Univ. Press, 1991).
20.	Deblonde, G. & Peltier, W. R. Clim. Dynam. 5, 103−110 (1990).
21.	Manabe, S. & Broccoli, A. J. J. atmos. Sci., 42, 2643−2651 (1985). | Article | ISI |
22.	Harvey, L. D. D. J. geophys. Res. 94 (D10), 12873−12884 (1989).
23.	Baliunas, S. & Jastrow, R. Nature 348, 520−523 (1990). | Article |
24.	Chappellaz, J. et al. Nature 345, 127−131 (1990). | Article | ISI | ChemPort |
25.	Delmas, R. J. & Legrand, M. in The Environmental Record in Glaciers and Ice Sheets (eds Oeschger, H. & Langway, C. C.) 319−341 (Wiley, New York, 1989). | ChemPort |
26.	Harvey, L. D. D. Nature 334, 333−335 (1988). | Article |
27.	Anderson, T. L. & Charlson, R. J. Nature 345, 393 (1990). | Article |
28.	Newman, M. J. & Rood, R. T. Science 198, 1035−1037 (1977). | ISI | ChemPort |
29.	Thompson, S. L. & Barron, E. J. J. Geol. 89, 143−167 (1981). | ISI |
30.	Kiehl, J. T. & Dickinson, R. E. J. geophys. Res. 92(D3), 2991−2998 (1987). | ChemPort |
31.	Budyko, M. I., Ronov, A. B. & Yanshin, A. L. History of the Earth's Atmosphere (Springer. New York, 1987).
32.	Berger, W. H. & Spitzy, A. Paleoceanography 3, 401−411 (1988).
33.	Popp, B. N. et al. Am. J. Sci. 289, 436−454 (1989). | PubMed | ChemPort |
34.	Berner, R. A. Science 249, 1382−1386 (1990). | ISI | ChemPort |
35.	Berner, R. A. Nature 358, 114 (1992). | Article | ISI |
36.	Minkoff, J. Signals. Noise & Active Sensors (Wiley, New York. 1992).
37.	Crowley, T. J. J. Clim. 3, 1282−1292 (1990). | Article |
38.	Barron, E. J. Paleoceanography 2, 729−739 (1987).
39.	CLIMAP Project Members Science 191, 1131−1137 (1976). | ISI |
40.	Dansgaard, W. et al. in Climate Processes and Climate Sensitivity (eds Hansen, J. E. & Takahashi, T.) 288−298 (American Geophysical Union, Washington DC, 1984).
41.	Bradley, R. S. Quaternary Paleoclimatology, 132 (Unwin Hyman, Boston, 1985).
42.	Johnsen, S. J. et al. Nature 359, 311−313 (1992). | Article | ISI |
43.	Barron, E. J. & Washington, W. M. in The Carbon Cycle and Atmospheric CO2: Natural Variations Archean to Present (eds Sundquist, E. T. & Broecker, W. S.) 546−553 (American Geophysical Union, Washington DC, 1985).
44.	Stute, M. et al. Science 256, 1000−1003 (1992). | ChemPort |
45.	Emiliani, C. Science 257, 1462 (1992).