Greenhouse gas and sulfate aerosol experiments using a simple global-energy-balance model

A one-dimensional global-energy-balance model is used to simulate the climate response of increasing atmospheric greenhouse gas concentrations and sulfate aerosol loadings. Model output indicates that a change in equivalent carbon dioxide from 300 to 450 ppm produces a global warming of 0.69° C (1.24° F), and a doubling to 600 ppm generates a warming of 1.57° C (2.83° F). In both simulation experiments, the greatest warming appears in the high latitudes of the Northern Hemisphere. Model results show that increasing sulfate aerosol levels generates a global cooling of 0.32° C (0.58° F), with the largest cooling occurring in the industrialized mid-to-high latitudes of the Northern Hemisphere. When the effects of equivalent carbon dioxide and sulfates are simulated together to represent changes that have occurred in the past century, the model generates a global warming of 0.30° C (0.54° F), with the greatest warming continuing to occur in the mid-to-high latitudes of the Northern Hemisphere. The latent heat transfer values, which provide a rough indication of projected trends in precipitation levels, increase globally by 2.3% as the model's representation of atmospheric composition is perturbed by greenhouse gases and sulfate aerosols. These basic results from the simple one-dimensional energy balance model are broadly consistent with simulations using far more sophisticated three-dimensional general circulation models and with the trends in global temperature and precipitation observed over the past century.