Two complementary models invoking ion heating are presented which, together with pump depletion, quantitatively account for the principal observations (reflectivity, spectral shape, saturation) of stimulated Brillouin scattering (SBS) in a CO2 laser/plasma interaction experiment. A simple energy balance model, which incorporates ion heating and includes a consistent calculation of ion wave damping, is applicable for steady state convective growth of the ion waves (long interaction times). A more refined model, which includes a calculation of the trapped ion fraction (along with heating), is applicable for SBS in a transient regime. Strong ion wave damping has been consistently observed in both cases in our high intensity CO2 laser/plasma scattering experiments. A variety of measurements have been made to investigate the basic features of SBS and associated density fluctuations for both long pulse (40 ns) and short pulse (2 ns) CO2 laser irradiation. Measured parameters reported here include plasma density, temperature, density scalelength, SBS reflectivity, and spectral characteristics. Together with previous measurements of density fluctuations (amplitude, wavenumber spectra, spatial and temporal information), the observed behavior confirms that Brillouin scattering is dominated by strong ion trapping, heating and ion wave damping for the laser/plasma parameters prevailing in these experiments.