Reply to Comment on "Radiative Transfer in CO2-Rich Atmospheres: 1. Collisional Line Mixing Implies a Colder Early Mars"

Turbet and Tran (2017) have identified that we mistakenly used air-broadened CO2 absorption spectra to generate coefficients for a rapid radiative transfer code, instead of self-broadened spectra. The resulting underestimation of absorption by CO2 led us to suggest that when the effects of CO2 line mixing are taken into account, surface temperatures on early Mars are up to 15K colder than those calculated in previous studies, in which empirical corrections of the CO2 spectrum were used ( factors). Using the correct CO2 absorption spectra, including the effects of line mixing, Turbet and Tran (2017) found that the surface temperature is colder by only 2K than temperatures calculated with the factor approach. While we acknowledge the mistake, and thank Turbet and Tran (2017) for finding and correcting it, we note that our main conclusions hold that surface temperatures are overestimated when empirical factors are used instead of a full account of CO2 line mixing in radiative transfer calculations in CO2-rich planetary atmospheres. Additionally, we emphasize that the rapid radiative transfer model we developed and tested is useful for studies of planetary climate, provided the correct absorption spectra are used to generate new k coefficients.