This paper describes a key set of processes used by the Intergovernmental Panel on Climate Change to estimate climate outcomes from emissions scenarios. The text is well-written. As such it is worthy of publication. I do however have some comments and proofing points for the authors to consider, as follows:

• There is no discussion as far as I can tell of the impact of harmonisation and infilling at the regional scale. Basing these steps on global values (of CO2) implicitly assumes that the ratio of CO2 to other species is homogeneous across space, which is unlikely to be true. What are the implications of this workflow for use of the regional emissions data in the AR6 database?
• This is a question so naive that I am slightly embarrassed to ask... Are the emissions data in the AR6 database the unadjusted submitted data, or are they adjusted data (harmonised, infilled, or both)? If unadjusted, then users should exercise caution in estimating emissions-climate properties (such as TCRE) from the database. If adjusted, users should know they do not necessarily match the submitted data and may exhibit biases from processing. Either way, this should be clear in the database metadata (e.g. https://data.ece.iiasa.ac.at/ar6/#/about) and in the paper. Perhaps it is and I am unobservant, but I did spend a while looking!
• What is the justification for the scenario selection criteria? And what is the sensitivity of the number of included scenarios to variations in these criteria? The selection criteria are described briefly in lines 300-310 and listed in Supplementary Figure 1, but no reasoning for these criteria or the threshold values is given, either in this manuscript or in IPCC WG3 AR6 Annex 3.
• Table 1 appears to show harmonisation methods only, not infilling methods as suggested by the caption. It would be good to see the infilling procedures included in the table - perhaps as an extra column?
• Lines 561-564: while I think the authors are correct that sensitivity to absolute warming can act as a proxy for sensitivity to uncertainty in a bundle of other factors, the relationships are not intuitive. The reader would benefit from a brief explanation of how to infer from Supplementary Figure 1 the implications for uncertainty in forcing or of harmonisation & infilling emissions. 
• In Figure 7, can the authors provide an additional panel showing the impact of infilling and harmonisation on other forcings beyond Kyoto Gases? These are also important, and perhaps where some of the largest (proportional) changes arise from infilling and harmonisation.

And a few proofing suggestions:

• Line 75: italicise "climate"?
• Line 112: missing "the" between "of" and "limited".
• Lines 466-467: this sentence needs completing.
• Table 1 caption: A ** footnote is explained, but I don't see that symbol used in the table. 
• Figure 5, panels B-D: Could the authors explain in the caption how the scenarios have been ordered? Would it be informative to order them by magnitude of ODY_1.5, for instance?

This paper details the climate assessment processing steps developed between IPCC Working Groups I and III to assess temperature outcomes of emissions pathways and introduces an open source climate assessment Python package that can facilitate this processing. The processing steps include (1) vetting of emissions scenarios submitted to the AR6 Scenario Explorer, (2) harmonization of vetted emissions scenarios with historical emissions, (3) infilling of missing species in the emissions scenario, and (4) assessment of the emissions-climate response with three climate emulators. The paper then evaluates the impact of this processing on global-mean temperature projections and effective radiative forcing statistics before analyzing overshoot degree years and ‘Paris-compatible’ emissions scenarios.

The paper is well-written and provides a valuable reference for elucidating the IPCC scenario-emissions process. I would recommend publication with a few qualifications below to better emphasize the novelty of this contribution (for instance fore-fronting the statement in lines 245-248).

General

• This paper read to me as part review/part analysis/part overview of a new community tool, which is a lot to take on but is very useful to the climate community at large. My recommendation would be to highlight the community tool more clearly throughout the methods section to encourage its uptake. This could include providing a schematic of the workflow either in the main text or supplement or clarifying throughout the methods section how and where the climate assessment workflow package was used. I’ll note that while the workflow illustrated in Figure 1 is excellent, it is more supportive of the review portion of the text as opposed to elucidating the packages, emulators, and analysis included in the community tool.
• Why aren’t CICERO-SCM results reported in the abstract? Or make it clearer that it is used only for sensitivity analysis.
• Suggestion: In addition to Table 2 in the Supplementary file, a bar graph displaying the vetting ‘success’ of scenarios from each model would be useful. It would emphasize the number of scenarios that are included by a disproportionate number of IAMs (as discussed in section 5.1.1).
• It is exciting to consider the use of emulators for variables beyond global estimates of GSAT, but other variables have not yet been comprehensively evaluated, such as precipitation. Should there be some discussion of the uncertainty and potential of emulators to provide societally relevant metrics beyond GSAT? Similarly, more discussion of the regional emissions data vetting and application would be useful as a means of underpinning the recommendation in the concluding sentence.

Specific

• Line 300: delete in: ‘...climate mitigation options [in] were extensively...’
• Line 490: Chen et al. 2021 not included in the references
• Style: Remove the indent from lines 219, 223, 226, 228
• Line 252: “A growing body of research has been developed to describe[ing] analyses that compare…” (Or something along these lines)
• Line 296: italicize ‘climate assessment’ as is done on line 814
• Line 300: delete 'in': “Global scenarios used to assess climate mitigation options [in] were extensively…”
• Line 444: delete 'above': “Beyond these, AR6 WGIII includes categories [above] relevant for higher emissions scenarios that…”
• Line 765: delete 'a': “While overshoot indicators like ODY₅ may immediately be [a] useful as an…
• Supplement: Include the number of scenarios considered in Table 2.