Dear Roger Francey

Thank you very much for addressing the comments made by the two referees. As the referees pointed out, the major concerns have all been clarified. The addition of the TRENDY models also strengthens your case for a dominant influence of interhemispheric (IH) exchange processes on IHCO2 gradients. Now, uncertainties are also included where appropriate. Minor issues have been clarified and the overall presentation is significantly improved/streamlined. The revised manuscript can be almost accepted as is after considering the suggestions below.

Best regards,

Christoph Zellweger

Line 254: maybe remove the question mark at the end of the sentence?

Figure 9 - since the authors completed the comparison, could the results with Nino3 and Nino3.4 also be included somewhere (e.g. in the supplement)? Just stating “(conclusions are similar using Nino3 or Nino3.4)” on line 329 is a little bit vague.

In Figure 9 state in figure caption what is the blue dashed line.

Consistency when writing interhemispheric and inter-hemispheric. There are also other inconsistencies in the writing (e.g., fossil fuel vs Fossil Fuel), hence a detailed re-reading/checking would be great.