An ensemble of 20th century climate simulations with various combinations of solar, greenhouse gas (GHG), sulfate and ozone forcings are analyzed in the Parallel Climate Model (PCM), a global coupled climate model, to address the question of are there different climate system responses to solar versus GHG (infrared) forcing? Confirming previous results, much of early century warming in the PCM is related to solar forcing, and late century warming to anthropogenic GHGs. Response of climate system to early century (solar) and late century (GHG+sulfates) is different in terms of relatively stronger tropical convection and intensified Hadley Circulation in early century. Stronger early century South Asian and West African monsoons in JJA from solar forcing are associated with greater relative land-sea temperature contrast. Intensified tropical convergence zones over ocean in DJF from solar forcing are associated with coupled ocean-atmosphere feedbacks involving surface energy budget and clouds. These results suggest that relatively small variations of solar forcing can be magnified by coupled processes in the tropics related to tropical convection.