Estimating the past aerosol radiative effects and their uncertainties is an important topic in climate science. Aerosol radiative effects propagate into large uncertainties in estimates of how present and future climate evolves with changing greenhouse gas emissions. A deeper understanding of how aerosols interacted with the atmospheric energy budget under past climates is hindered in part by a lack of relevant paleo observations and in part because less attention has been paid to the problem. Because of the lack of information we do not seek here to show the change in the radiative forcing due to aerosol changes, but rather just estimate the uncertainties in those changes. Here we argue that current uncertainties from emission uncertainties (90% confidence interval range spanning 2.8 W/m2) are just as large as model spread uncertainties (2.8 W/m2) in calculating preindustrial to current day aerosol radiative effects. There are no estimates for radiative forcing for important aerosols such as wildfire and dust aerosols in most paleoclimate time periods. However, qualitative analysis of paleoclimate proxies suggests that changes in aerosols in different past times are similar in magnitude to changes in aerosols between preindustrial and current day, plus there is the added uncertainty from the variability in aerosols and fires in the preindustrial. From the limited literature we estimate a paleoclimate aerosol uncertainty for the last glacial maximum relative to preindustrial of 4.8 W/m2. The uncertainty in the aerosol feedback in the natural Earth system over the paleoclimate (last glacial maximum to preindustrial) is estimated to be about 3.2 W/m2/°K as a first estimate of the 90% confidence interval range. In order to assess the uncertainty in historical aerosol radiative effects, we propose a new model intercomparison project, which would include multiple plausible emission scenarios tested across a range of state-of-the art climate models over the historical period. These emission scenarios would then be compared to the available aerosol observations to constrain which are most probable. In addition, future efforts should work to characterize and constrain paleoaerosol forcings and uncertainties. Careful propagation of aerosol uncertainties in the literature is required to ensure consideration of all the uncertainties.