Dear authors,

Please go ahead and submit a revised version of your manuscript taking into consideration all of the reviewers' comments and my earlier comment about the difficult to follow text around your though experiment. I will be away Apr 3 to 13 so will only be able to review your revised manuscript after I am back. Reviewer #1 expressed concerns about the difficult to follow text as well so please try to make your text simple to follow. I look forward to your revised manuscript.

Best regards,
Vivek.

Dear Authors,

Thank you for making changes to your manuscript following reviewers' comment. The manuscript reads much better now and it is a much more easy read now. I only have few minor editorial corrections that I would request you to take into account. I have attached an annotated scanned PDF version of your manuscript with my hand written corrections which should be easily readable.

Please take these into account and submit the final version.

Thanks,
Vivek.

Dear authors,

Thank you taking into account the minor corrections I suggested. I am accepting your manuscript but please make the following small corrections when uploading your files for publication.

In the final manuscript the sentences from Page 13, line 34 to Page 14, line 2 still need some rewording. Currently it reads as follows ...

For instance, the low-CO2-rate scenario RCP4.5 shows the largest GPP enhancement (∆GPP ∼2.84 Pg C yr−1 , Tab. 3) for an increase of 155 ppm CO2. This estimates is ∼39% and ∼20% larger than in the scenarios with higher CO2 rates for the same total increment in CO2 concentration, namely 1pctCO2 (∆GPP ∼2.05 Pg C yr−1 , Tab. 3) and RCP8.5 (∆GPP ∼2.38 Pg C yr−1, Tab. 3), respectively.

May I suggest something along the following lines ...

For instance, in the RCP4.5 scenario (which is characterized by a lower rate of increase of CO2 than in the 1pctCO2 and RCP8.5 scenarios) an increase of 155 ppm CO2 yields a GPP enhancement (∆GPP) of ∼2.84 Pg C yr−1 (see Tab. 3). This GPP enhancement is ∼39% and ∼20% larger, than in the 1pctCO2 (∆GPP ∼2.05 Pg C yr−1 , Tab. 3) and RCP8.5 (∆GPP ∼2.38 Pg C yr−1, Tab. 3) scenarios, respectively, for the same total increase in CO2 concentration. Both these scenarios are characterized by a faster rate of CO2 increase than RCP4.5.

Thanks,
Vivek.