Including the efficacy of land ice changes in deriving climate sensitivity from paleodata

Stap, Lennert B.; Köhler, Peter; Lohmann, Gerrit

doi:https://doi.org/10.5194/esd-10-333-2019

Articles | Volume 10, issue 2

https://doi.org/10.5194/esd-10-333-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/esd-10-333-2019

© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 10, issue 2

Research article

| Highlight paper

|

14 Jun 2019

Research article | Highlight paper |

| 14 Jun 2019

Including the efficacy of land ice changes in deriving climate sensitivity from paleodata

Lennert B. Stap, Peter Köhler, and Gerrit Lohmann

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Final revised paper (published on 14 Jun 2019)
Preprint (discussion started on 17 Dec 2018)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Review of "Including the efficacy of land ice changes in deriving climate"', Anonymous Referee #1, 14 Jan 2019
- AC1: 'Reply to the comments of both reviewers', Lennert Stap, 25 Feb 2019
RC2: 'Review', Anonymous Referee #2, 15 Jan 2019
- AC1: 'Reply to the comments of both reviewers', Lennert Stap, 25 Feb 2019

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (10 Mar 2019) by Daniel Kirk-Davidoff

AR by Lennert Stap on behalf of the Authors (14 Mar 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (15 Mar 2019) by Daniel Kirk-Davidoff

RR by Anonymous Referee #1 (01 Apr 2019)

RR by Anonymous Referee #2 (10 Apr 2019)

Suggestions for revision or reasons for rejection

The manuscript is sufficiently improved that I can follow what the authors are trying to do, and attempt a review.

Overall, within the practical constraints of the state-of-the-art, I think the work is reasonable enough, although some of the sources of uncertainty need better highlighting. I have a few comments of varying degrees of potential importance.

p2.
"Ceteris paribus" - the language of the journal is English and superfluous Latin should, in my opinion, be avoided. Not all readers have a first language that has a Latin base. I Googled the meaning, and do not understand why you don't use English here.

p3.
"Repeat" not "recapitulate"

p4.
I suspect that the 0.64 is highly uncertain and state dependent. It would be good if you gave a rough estimate of your uncertainty for this value.

p5.
On p4, you state that, to convert from S_[LI,CO2] to S^a you should multiply by 0.64. Therefore DT_G on in eqn 10 should also be multiplied by 0.64. This may solve all your problems in terms of reconciling CLIMBER and the data as, if I understand correctly, you need to include this multiplicative factor for the data based analyses, but not for the CLIMBER analysis.

P5
"Any specific moment", "in time" ... I do not think this is what you mean. Equation 1 relates to the steady state! This also causes me to ask what time averaging is used for the CLIMBER analysis on p7-8...? (Maybe this is already stated somewhere but I do not recall seeing this mentioned in the manuscript...?)

p6.
I don't think this is really a "validation" as such - more an "illustration" perhaps? Clearly CLIMBER is very simplified and other models may have quite different result. A sentence explaining why this information is not forthcoming from GCMs would be appropriate (ie you are forced to use a simplified model because of the CPU overhead).

P7. "Note that, in the case S... is equal to... The fit further shows decreasing..." This seems silly, and confusing, especially since you then use it as a reason for referring in a confusing way to S_CO2,LI later on. Just call it S^E_[CO2]. It is surely clear to anyone who has managed to get this far through the paper what is meant.

P8
Fig 3b looks to be less linear not more linear than 3a

Again we have an "any moment in time". Rephrase please.

The section "In principal [which should be "principle", but these days we rely on copy-editing to pick up this kind of thing] ... (Fig3c)." Should be moved to p7 where the LGM is first mentioned in this context.

Please remove all the "old approach" / "new approach" labels. Give the approaches names, or reference the equations, or other papers. Otherwise people do not know what you are talking about, and they will be even more lost in the future when there is a new new approach and your approach becomes the old approach!

ANICE is used to convert from temperature to radiation. After seeing some of the ice model inter-comparison results I suspect this is a major source of uncertainty. If you agree, it would be good to see this at least mentioned.

p9
"Therefore, these results...similar to the of proxy data..."
I do not know what you mean. Why?

P10 and throughout. The uncertainty ranges are quite strange because they exclude an awful lot of known uncertainty. Maybe you could be more careful about stating in the Abstract and Conclusion what these ranges include and do not include in terms of known uncertainties. Also, what are the quoted ranges - 1 standard deviation? 2,3? 95%??

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ED: Publish subject to minor revisions (review by editor) (29 Apr 2019) by Daniel Kirk-Davidoff

AR by Lennert Stap on behalf of the Authors (09 May 2019) Author's response Manuscript

ED: Publish subject to technical corrections (27 May 2019) by Daniel Kirk-Davidoff

AR by Lennert Stap on behalf of the Authors (29 May 2019) Manuscript

Short summary

Processes causing the same global-average radiative forcing might lead to different global temperature changes. We expand the theoretical framework by which we calculate paleoclimate sensitivity with an efficacy factor. Applying the revised approach to radiative forcing caused by CO₂ and land ice albedo perturbations, inferred from data of the past 800 000 years, gives a new paleo-based estimate of climate sensitivity.