Dear Dr Boudinot,

Thank you for submitting your responses to the comments and suggestions of the referees. The reviewers are generally positive about the manuscript. Though it is not a traditional type of manuscript for Climate of the Past, I think it will be of interest to the journal’s readers after some revision. Your responses suggest a willingness to engage with the constructive suggestions of the referees, so I invite you to submit a revised manuscript to Climate of the Past for further consideration.

Several of the suggestions, in particular, strike me as important ways to broaden the potential interest in this manuscript: a glossary; fuller consideration of geological time as a source of uncertainty; and a deeper exploration of relevant literature along the lines of the suggestion from Reviewer 1. I also encourage you to give some additional thought to the term “indicator”, which is commonly used in more nuanced way than merely as a synonym for “qualitative” (e.g. indicator taxa such as palm mandate mean winter temperatures above freezing; or ice wedge casts are an indicator for past permafrost conditions).

Sincerely,
Alberto Reyes (handling editor)

Dear Dr Boudinot,

I have now reviewed your revised manuscript for Climate of the Past. I would like you to consider one last set of comments and suggestions before making a final decision on this manuscript. The attached PDF includes some minor editorial suggestions. More substantively, in your revised manuscript please consider the points that follow below. With your revised submission, please include a response letter that states how the manuscript was changed in response to these points or why you think the suggestions aren’t correct/relevant.

Sincerely,
Alberto Reyes (handling editor)

-The term “paleotemperature measurements” comes up frequently. In some contexts I think this is appropriate, for example where it’s clear that you’re referring to measurements undertaken to derive a paleotemperature estimate. In other cases, for example line 23 in the abstract, my sense is that “paleotemperature estimates” is a more appropriate because the datum of information (e.g. MAT at X location Y thousand years ago) was not measured but rather estimated from measurements.

-The point about uncertainty and geological time is an important one and it’s elegant to turn to Urey’s pioneering work to make the point. But phrasing of the point is a bit awkward and I recommend some wordsmithing.

-Line 186: You may not agree, but it seems optimistic to suggest that calibration can “effectively remove” the influence of CCFs in even the most well-characterized proxy system. Is it more realistic to instead say “account for” or “mitigate against”?

-The section from lines 305 to 320 is interesting, and I’m not sure if I agree with the assessment that sample processing, human error, etc give rise to “unquantifiable uncertainty”. Tools such as secondary reference standards (ie separate from instrument calibration standards), replicate analyses, and process blanks are all ways to account for and, in some cases, quantify the impacts of sample handling. I suggest a long chat with someone who runs a mass spectrometer for a living… they would likely have some good thoughts on this.

-Re: transfer functions, I was surprise to see the discussion come up relatively late. Since transfer functions are the sets of equations used in “correlation constrained proxies”, it would seem natural to bring up the term there. This would also provide an opportunity to give some more examples of correlation constrained proxies (e.g. chironomids, pollen, ice core/permafrost water isotopes, etc). This would contribute to addressing, in part, the next point…

-Reading the manuscript again, there’s a perception of beating up a bit on the TEX proxy. I’m not sure if this is intended or not (or maybe I’m reading more into it because I’m also handling a manuscript that is critical of current TEX calibration schemes). I can’t point to anything specific, but if that wasn’t your intention I’d urge you to take a close read of the sections relating to TEX and see if the tone can be subtly shifted to avoid that perception. You could also consider adding a few sentences of text to summarize some of the major contributions made by workers applying TEX to paleoclimate problems.

-Fig 1: the numbers on the X axis seems impossibly low to me. Surely there are (at least!) 90 papers a month published in various journals that discuss paleotemperature. You don’t need this figure to support the point that there has been an increasing scholarly interest in paleoclimate over the last several decades, so I suggest deleting it or re-doing the analysis with more inclusive search criteria.

Dear Dr Boudinot,
Thank you for considering my last set of comments on your manuscript. I think this is a really interesting perspective piece and am pleased to recommend publication in Climate of the Past.

Sincerely,
Alberto Reyes