I have now received reports from three referees and thank the authors for their detailed responses to the referees’ comments. Based on these three reviews and my own reading of the manuscript, I find that the paper may be of scientific interest to HESS readers, but that the manuscript requires notable improvements.
I agree with the referees that the choice of terms ‘flood’ and ‘drought’ is inappropriate, because the 5th/95th percentiles of the flow distribution reflect neither (irrespective of whether these simplifications have been made in the published literature); the changes need to be made throughout the manuscript and title. The authors suggest using the term ‘risk’ instead of ‘intensity’, but this is also inappropriate (risk does not mean ‘likelihood of occurrence’, but reflects the interaction of hazard and vulnerability). There was also some confusion regarding the data used in the manuscript (routed runoff); these details should be provided to avoid any further confusion.
Additionally, the referees make some very valid suggestions for improving the manuscript: clarifying the knowledge gap that the paper addresses, justifying methodological choices more fully (e.g. GHMs), and providing a better discussion of the findings and their implications.
All three referees have requested to review the paper again after corrections have been made, and I consider that to be a fair request. I would therefore like to invite the authors to upload a revised manuscript for further review by the referees, incorporating the proposed changes and additions, and making any other modifications where they see fit.
I look forward to receiving the revised manuscript.
With best regards,
Louise Slater

Dear Authors,

The revised manuscript 'Global change in streamflow extremes under climate change over the 21st century' has now been reviewed by two referees. Both reviewers are supportive of the paper and consider that the revision has addressed their concerns. I am also happy with the revised version of the manuscript and am glad to recommend publication.

Sincerely,
Louise Slater