The manuscript is a nice overview over northern hemisphere upper ocean deoxygenation as simulated by a few CMIP5 models. It concentrates on the different declines in the upper North Atlantic (small) and North Pacific (large). The slowdown of the North Atlantic nutrient stream is suggested to explain the different deoxygenation rates in the two basins. This provides an interesting story, which I find plausible and worthwhile of eventual publication. However, all arguments are based on relatively vague qualitative descriptions of basin scale patterns of simulated changes rather than being mechanistically 'confirmed' (line 199) or quantiatively estimated as providing 'most' of the simulated deoxygenation (line 222). There is no mentioning of the possible role of other processes (e.g. changes in up- or downwelling, subpolar gyre strength, fresh water supply and stratification, carbon export by vertical mixing (including deep convection in the N.Atlantic) of particulate or organic matter - are these included in the diagnosed export production of Fig. 9?).
Two expert reviewers have provided useful comments and thoughtful criticism, which I find valid. Unfortunately, the current responses of the authors fail short of satisfactorily addressing those points. Saying that the required model fields are unfortunately not available is not an appropriate scientific reasoning (it would only say that the study was ill-designed - which, I think, is not the case). One could, for example, use one model for which the required temporal resolution output is available and estimate the errors made when considering annual mean tracer fields only.
I therefore would like to ask the authors to carefully address all the points raised by the reviewers and also discuss possible other mechanisms as well. I expect that this will become a scientifically very useful contribution and look forward to seeing a revised version.
Many thanks and best regards,
-Andreas

Handling Associate Editor, Andreas Oschlies

The authors have substantially revised and improved the manuscript. However, both reviewers still have valid concerns and make constructive suggestions to resolve them in a -what I think- manageable way. I encourage the authors to carefully address the remaining concerns of the two reviewers and submit a suitably revised version.

The authors have now satisfactorily responded to all the remaining concerns raised by the reviewers, in particular a more quantitative estimate of the North Atlantic nutrient budget. This has improved content and clarity of the manuscript. I am happy to recommend publication as is.
Many thanks for the stimulating paper!
Best regards,
Andreas Oschlies