I apologize for the delay in responding to your proposed revisions to this paper. After reading the original manuscript, reviews, and proposed revisions I recommend that you submit the revised manuscript along the lines that you propose. I made some editorial comments in the attached file for you to consider. I do not think the revised paper needs to go back to the reviewers, based on their comments.

I do share reviewer 1's concern about possible confusion related to the "dual response." I understand why you take the approach you did. I just suggest that you be careful with the terminology (first response, unique response, etc.) to make the ideas clear to the reader.

Thank you for the revised manuscript addressing the reviewer and editor comments. I am happy to accept this paper for publication subject to just some small corrections based on a quick reading (see below).

Page 1. Line 24. Do you need “Without an a priori guess” here? Is the intent to say that the model does this without being forced to? With this sentence construction the reader may be looking for what happens when there is an a priori guess. I suggest some rewording.

Page 2, line 1. I suggest deleting “The”.

Page 2, line 25. Not just 12C is released. Use “13C depleted carbon”?

Page 4, line 6. Fix parentheses in Rempfer reference.

Page 5, line 16. I suggest “Consistent” rather than “Consistently”

Page 8, line 18. I am not sure what “resorbed” means here.