Correction for differential extinction by CO₂ ice of the CO₂ gas emission features. The blue line shows the continuum subtracted data with the CO₂ ice feature removed. The best-fit LTE model of CO₂ with extinction correction, but without any correction for ice absorption (orange) overproduces the Q and P-branch emission. The estimated optical depth of the CO₂ ice feature (dashed grey line) is applied as a scaling factor to the same best-fit model (green curve), which significantly improves the fit to the Q-branch, though the P-branch features are now somewhat under-produced.