Climatic Change

, Volume 43, Issue 3, pp 495–511

Detectability of Summer Dryness Caused by Greenhouse Warming

  • R. T. Wetherald
  • Syukuro Manabe
Article

Abstract

This study investigates the temporal and spatial variation of soil moisture associated with global warming as simulated by long-term integrations of a coupled ocean-atmosphere model conducted earlier. Starting from year 1765, integrations of the coupled model for 300 years were performed for three scenarios: increasing greenhouse gases only, increasing sulfate-aerosol loading only and the combination of both radiative forcings. The integration with the combined radiative forcings reproduces approximately the observed increases of global mean surface air temperature during the 20th century. Analysis of this integration indicates that both summer dryness and winter wetness occur in middle-to-high latitudes of North America and southern Europe. These features were identified in earlier studies. However, in the southern part of North America where the percentage reduction of soil moisture during summer is quite large, soil moisture is decreased for nearly the entire annual cycle in response to greenhouse warming. A similar observation applies to other semi-arid regions in subtropical to middle latitudes such as central Asia and the area surrounding the Mediterranean Sea. On the other hand, annual mean runoff is greatly increased in high latitudes because of increased poleward transport of moisture in the warmer model atmosphere. An analysis of the central North American and southern European regions indicates that the time when the change of soil moisture exceeds one standard deviation about the control integration occurs considerably later than that of surface air temperature for a given experiment because the ratio of forced change to natural variability is much smaller for soil moisture compared with temperature. The corresponding lag time for runoff change is even greater than that of either precipitation or soil moisture for the same reason. Also according to the above criterion, the inclusion of the effect of sulfate aerosols in the greenhouse warming experiment delays the noticeable change of soil moisture by several decades. It appears that observed surface air temperature is a better indicator of greenhouse warming than hydrologic quantities such as precipitation, runoff and soil moisture. Therefore, we are unlikely to notice definitive CO2-induced continental summer dryness until several decades into the 21st century.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Chen, T. H., Henderson-Sellers, A., Milly, P. C. D., Pitman, A. J., Beljaars, A. C. M., Polcher, J., Abramopoulos, F., Boone, A., Chang, S., Chen, F., Dai, Y., Desborough, C. E., Dickinson, R. E., Dumenil, L., Ek, M., Garratt, J. R., Gedney, N., Gusev, Y. M., Kim, J., Koster, R., Kowalczyk, E. A., Lavel, K., Lean, J., Lettenmaier, D., Liang, X., Mahfouf, J.-F., Mengelkamp, H.-T., Mitchell, K., Nasonova, O. N., Noilhan, J., Robock, A., Rosenzweig, C., Schaake, J., Schlosser, C. A., Schulz, J.-P., Shao, Y., Shmakin, A. B., Verseghy, D. L., Wetzel, P., Wood, E. F., Xue, Y., Yang, Z.-L., and Zeng, Q.: 1997, ‘Cabauw Experimental Results from the Project for Intercomparison of Land-Surface Parameterization Schemes’, J. Climate 10, 1194-1215.Google Scholar
  2. Gregory, J. M., Mitchell, J. F. B., and Brady, A. J.: 1997, ‘Summer Drought in Northern Mid-Latitudes in a Time-Dependent CO2 Climate Experiment’, J. Climate 10, 662-686.Google Scholar
  3. Haywood, J. M., Stouffer, R. J., Wetherald, R. T., Manabe, S., and Ramaswamy, V.: 1997, ‘Transient Response of a Coupled Model to Estimated Changes in Greenhouse Gas and Sulfate Concentrations’, Geophys. Rev. Lett. 24, 1335-1338.Google Scholar
  4. Houghton, J. T., Meira Filho, L. G., Callander, B. A., Harris, N., Kattenberg, A., and Maskell, K.: 1996, ‘Climate Change 1995: The IPCC Second Scientific Assessment’, Cambridge University Press, Cambridge, p. 572.Google Scholar
  5. Jones, P. D. and Briffa, K. B.: 1992, ‘Global Surface Air Temperature Variations during the Twentieth Century, Part I: Spatial, Temporal and Seasonal Details’, The Holocene 2, 165-179.Google Scholar
  6. Kellogg, W. W. and Zhao, Z.-C.: 1988, ‘Sensitivity of Soil Moisture to Doubling of Carbon Dioxide in Climate Model Experiments, Part I: North America’, J. Climate 1, 348-366.Google Scholar
  7. Leggett, J., Pepper, W. J., and Swart, R. J.: 1992, ‘Emission Scenarios for the IPCC: An Update’, in Houghton, J. T., Callendar, B. A., and Varney, S. K. (eds.), Climate Change: Supplementary Report to the IPCC Scientific Assessment, Cambridge University Press, Cambridge, pp. 74-95.Google Scholar
  8. Manabe, S.: 1969, ‘Climate and the Ocean Circulation: I. The Atmospheric Circulation and the Hydrology of the Earth's Surface’, Mon. Wea. Rev. 97, 739-774.Google Scholar
  9. Manabe, S.: 1998, ‘Study of Global Warming by GFDL Climate Models’, Ambio 27, 182-186.Google Scholar
  10. Manabe, S. and Wetherald, R. T.: 1975, ‘The Effects of Doubling the CO2 Concentration on the Climate of a General Circulation Model’, J. Atmos. Sci. 32, 3-15.Google Scholar
  11. Manabe, S. and Wetherald, R. T.: 1980, ‘On the Distribution of Climate Change Resulting from an Increase of CO2 Content of the Atmosphere’, J. Atmos. Sci. 37, 99-118.Google Scholar
  12. Manabe, S. and Wetherald, R. T.: 1987, ‘Large-Scale Changes of Soil Wetness Induced by an Increase in Atmospheric Carbon Dioxide’, J. Atmos. Sci. 44, 1211-1235.Google Scholar
  13. Manabe, S., Wetherald, R. T., and Stouffer, R. J.: 1981, ‘Summer Dryness Due To an Increase of Atmospheric CO2 Concentration’, Clim. Change 3, 347-386.Google Scholar
  14. Manabe, S., Stouffer, R. J., Spelman, M. J., and Bryan, K.: 1991, ‘Transient Responses of a Coupled Ocean-Atmosphere Model to Gradual Changes of Atmospheric CO2, Part I: Annual Mean Response’, J. Climate 4, 785-818.Google Scholar
  15. Manabe, S., Spelman, M. J., and Stouffer, R. J.: 1992, ‘Transient Responses of a Coupled Ocean-Atmosphere Model to Gradual Changes of Atmospheric CO2, Part II: Seasonal Response’, J. Climate 5, 105-126.Google Scholar
  16. Meehl, G. A. and Washington, W. M.: 1988, ‘A Comparison of Soil-Moisture Sensitivity in Two Global Climate Models’, J. Atmos. Sci. 45, 1476-1492.Google Scholar
  17. Mitchell, J. F. B. and Johns, T. C.: 1997, ‘On Modification of Global Warming by Sulfate Aerosols’, J. Climate 10, 245-267.Google Scholar
  18. Mitchell, J. F. B. and Warrilow, D. A.: 1987, ‘Summer Dryness in Northern Mid-latitudes Due To Increased CO2’, Nature 330, 238-240.Google Scholar
  19. Mitchell, J. F. B., Manabe, S., Meleshko, V., and Tokioka, T.: 1990, ‘Equilibrium Climate Change and its Implications for the Future’, in Houghton, J. T., Jenkins, G. T., and J. J. Ephraums (eds.), Climate Change: IPCC Scientific Assessment, Cambridge University Press, Cambridge, pp. 131-164.Google Scholar
  20. Mitchell, J. F. B., Johns, T. C., Gregory, J. M., and Tett, S. F. B.: 1995a, ‘Climate Responses to Increasing Level of Greenhouse Gases and Sulfate Aerosols’, Nature 376, 501-504.Google Scholar
  21. Mitchell, J. F. B., Davis, R. A., Ingram, W. J., and Senior, C. A.: 1995b, ‘On Surface Temperature, Greenhouse Gases and Aerosols: Models and Observations’, J. Climate 8, 2364-2386.Google Scholar
  22. Rind, D., Goldberg, R., Hansen, J., Rosenzweig, C., and Ruedy, R.: 1990, ‘Potential Evapotranspiration and the Likelihood of Future Drought’, J. Geophys. Res. 95D, 9983-10004.Google Scholar
  23. Schlesinger, M. E. and Mitchell, J. F. B.: 1987, ‘Climate Model Simulations of the Equilibrium Climate Response to Increased Carbon Dioxide’, Rev. Geophys. 25, 760-798.Google Scholar
  24. Wetherald, R. T. and Manabe, S.: 1995, ‘The Mechanisms of Summer Dryness Induced by Greenhouse Warming’, J. Climate 8, 3096-3108.Google Scholar

Copyright information

© Kluwer Academic Publishers 1999

Authors and Affiliations

  • R. T. Wetherald
    • 1
  • Syukuro Manabe
    • 2
  1. 1.Forrestal CampusGeophysical Fluid Dynamics Laboratory/NOAAPrincetonU.S.A.
  2. 2.Institute for Global Change Research/FRSGCTokyoJapan

Personalised recommendations