Long-term changes of the diurnal temperature cycle: implications about mechanisms of global climate change

Abstract We use a global climate model to investigate the impact of a wide range of radiative forcing and feedback mechanisms on the diurnal cycle of surface air temperature. This allows us not only to rule out many potential explanations for observed diurnal changes, but to infer fundamental information concerning the nature and location of the principal global climate forcings of this century. We conclude that the observed changes of the diurnal cycle result neither from natural climate variability nor a globally-distributed forcing, but rather they require the combination of a (negative) radiative forcing located primarily over continental regions together with the known globally-distributed forcing due to anthropogenic greenhouse gases. Tropospheric aerosols can account for part of the continentally-located forcing, but alone they do not damp the diurnal cycle as observed. Only an increase of continental cloud cover, possibly a consequence of anthropogenic aerosols, can damp the diurnal cycle by an amount comparable to observations. A corollary of these results is quantitative confirmation of the widely held suspicion that anthropogenic greenhouse gas warming has been substantially counterbalanced by a forced cooling. Under the assumption that the cloud change is sulfate driven, a further implication is that the net rate of global warming is likely to increase substantially in coming years. We note that, on the long run, the daily maximum temperature will increase by an amount not much less than the increase of the mean temperature.

[1]  M. J. Salinger.  Southwest Pacific temperatures: trends in maximum and minimum temperatures , 1995 .

[2]  J. Angell.  Annual and Seasonal Global Temperature Changes in the Troposphere and Low Stratosphere, 1960–85 , 1986 .

[3]  Donald J. Wuebbles,et al.  Radiative Forcing of Climate Changes in the Vertical Distribution of Ozone , 1990 .

[4]  The annual variation of surface temperatures over the world , 1992 .

[5]  G. B. Pant,et al.  Diurnal asymmetry of surface temperature trends over India , 1994 .

[6]  J. Hansen,et al.  Greenhouse effect of chlorofluorocarbons and other trace gases , 1989 .

[7]  Robert J. Charlson,et al.  Perturbation of the northern hemisphere radiative balance by backscattering from anthropogenic sulfate aerosols , 1991 .

[8]  S. Manabe,et al.  The Effects of Doubling the CO2 Concentration on the climate of a General Circulation Model , 1975 .

[9]  S. Manabe.  CLIMATE AND THE OCEAN CIRCULATION1 , 1969 .

[10]  Peter H. Stone,et al.  Efficient Three-Dimensional Global Models for Climate Studies: Models I and II , 1983 .

[11]  William B. Rossow,et al.  Long-Term Monitoring of Global Climate Forcings and Feedbacks , 1993 .

[12]  A. Oort,et al.  Upper-Air Temperature Trends over the Globe, 1958–1989 , 1993 .

[13]  T. Wigley,et al.  Could reducing fossil-fuel emissions cause global warming? , 1991, Nature.

[14]  J. Hansen,et al.  Climate Response Times: Dependence on Climate Sensitivity and Ocean Mixing , 1985, Science.

[15]  J. Hansen,et al.  Global trends of measured surface air temperature , 1987 .

[16]  J. K. Angell,et al.  Changes in Tropospheric and Stratospheric Global Temperatures, 1958-1988 , 1991 .

[17]  J. Hansen,et al.  Radiative forcing and climate response , 1997 .

[18]  Syukuro Manabe,et al.  The Effects of Changing the Solar Constant on the Climate of a General Circulation Model , 1975 .

[19]  Syukuro Manabe,et al.  THE ATMOSPHERIC CIRCULATION AND THE HYDROLOGY OF THE EARTH ’ S SURFACE , 1969 .

[20]  H. Cao,et al.  Simulated Diurnal Range and Variability of Surface Temperature in a Global Climate Model for Present and Doubled C02 Climates , 1992 .

[21]  Larry D. Travis,et al.  Remote sensing of aerosols with the earth-observing scanning polarimeter , 1992, Optics & Photonics.

[22]  J. Coakley,et al.  Climate Forcing by Anthropogenic Aerosols , 1992, Science.

[23]  John Theodore Houghton,et al.  Climate Change 1992 , 1992 .

[24]  M. Schlesinger,et al.  Implication of Anthropogenic Atmospheric Sulphate for the Sensitivity of the Climate System , 1992 .

[25]  P. Talkner,et al.  Asymmetric diurnal temperature change in the Alpine Region , 1994 .

[26]  T. Karl,et al.  Nighttime warming and the greenhouse effect , 1993 .

[27]  A. Lacis,et al.  Tropospheric gas composition and cloud structure of the Jovian North Equatorial Belt , 1993 .

[28]  T. Wigley,et al.  Marine and Land Temperature Data Sets: A Comparison and a Look at Recent Trends , 1991 .

[29]  Kevin P. Gallo,et al.  A new perspective on recent global warming: asymmetric trends of daily maximum and minimum temperature , 1993 .

[30]  A. Henderson‐sellers.  North American total cloud amount variations this century , 1989 .

[31]  J. Hansen,et al.  Wonderland climate model , 1997 .

[32]  R. Hanel,et al.  Infrared spectrometer for Voyager. , 1980, Applied optics.