Over the industrial period, aerosols have increased due to human activities and their effects on climate are the largest source of uncertainty in the current IPCC estimates of global climate forcing. Inhomogeneous distribution of aerosols in space and time poses a challenge in characterizing their properties and requires global measurements to assess their effects and reduce the associated uncertainties. In this paper we use global measurements from satellite for seven year time period to estimate the shortwave aerosol radiative forcing (SWARF) at the top-of-atmosphere (TOA) and discuss the associated uncertainties. For this, measurements of the TOA shortwave flux from CERES instrument and aerosol optical thickness from MISR instrument (both onboard Terra satellite) are used in this paper. High spectral and spatial resolution observations from Imager (MODIS) are used to identify clear sky conditions within CERES footprint. Global aerosol forcing and corresponding radiative forcing efficiencies will be discussed as a function of major aerosol regimes and for different seasons. This study should serve as a useful constraint for both numerical modeling simulations and satellite based estimates of TOA climate forcing due to aerosols.