A GCM comparison of Pleistocene super-interglacial periods in relation to Lake El'gygytgyn, NE Arctic Russia

Coletti, A. J.; DeConto, R. M.; Brigham-Grette, J.; Melles, M.

doi:https://doi.org/10.5194/cp-11-979-2015

Articles | Volume 11, issue 7

https://doi.org/10.5194/cp-11-979-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/cp-11-979-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 11, issue 7

Research article

|

10 Jul 2015

Research article |

| 10 Jul 2015

A GCM comparison of Pleistocene super-interglacial periods in relation to Lake El'gygytgyn, NE Arctic Russia

A. J. Coletti, R. M. DeConto, J. Brigham-Grette, and M. Melles

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Final revised paper (published on 10 Jul 2015)
Preprint (discussion started on 07 Aug 2014)

Interactive discussion

Status: closed

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

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- Supplement

RC C1389: 'referee's comment', Anonymous Referee #1, 28 Aug 2014
- AC C2013: 'Responses to Reviewer #1', Anthony J. Coletti, 01 Dec 2014
RC C1824: 'Referee Comment', Anonymous Referee #2, 03 Nov 2014
- AC C2015: 'Responses to Reviewer #2', Anthony J. Coletti, 02 Dec 2014

Peer-review completion

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

AR by Anthony J. Coletti on behalf of the Authors (25 Feb 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (27 Feb 2015) by Volker Rath

RR by Anonymous Referee #1 (23 Mar 2015)

Suggestions for revision or reasons for rejection

Comments on :

A GCM comparison of Plio–Pleistocene interglacial–glacial periods in relation to Lake El’gygytgyn, NE Arctic Russia.
By A. J. Coletti, R. M. DeConto, J. Brigham-Grette, and M. Melles

This revised manuscript greatly improved compared to its initial submission. A table supports the discussion of temperature and precipitation changes and helps the reader. Several references to previous work were added that bring more context to the study. The authors took care of being more precise in their wording.

However, many weaknesses already present in the initial submission are still present in the revised version. It is still not clear what is the key contribution of the paper. Part of the results presented here was already published in Melles et al (2012). What is exactly new contribution?

The issue of the reference simulation is still not clear. This unclear status becomes evident from the title of section 3.1, which is ‘control simulations’ (plural) but it is also present in the description and discussion where the ‘modern climate’ still sometimes appears as a reference. The authors tried to indicate their reference for each comparison but they failed to do so all through the text. We still can read ‘ …. temperatures are 1.6°C warmer’, without any indication of the reference (warmer than). I already indicated that the expression ‘temperature warmer than …’ should be avoided.

Now that it becomes easier to concentrate on science, I am wondering what is the major message of the authors. Indeed they are presenting many results but I am not sure what is the major point of the story. They are mostly discussing three variables (temperature, precipitation and vegetation) with additional ones for explanation of processes. They have model results and proxy reconstruction. They have different interglacials. My understanding is that they are more concentrating on the model-data comparison than on the comparison of the different interglacials.

Detailed comments

L 86-91: Do the authors use astronomical solution from Berger (see their line 86), from Laskar (their line 91) or their own astronomical solution (their answer to referee #1).
L 87: I thought that the authors choose 9ka for MIS1.
L91: “assuming the real climate system equilibrated within a half-precession cycle”. I do not understand what this means. Indeed the climate system is probably never at equilibrium.
L115: LIG is usually defined as last interglacial.
L159: the units are probably not correct here.
L199: “wetter than observations”. Is it really meteorological observation? From which station is it and where is it located and over which time interval? In that case it is present/modern information, not pre-industrial. Is the value (122) an absolute value or a deviation from some reference?
L202: the first figure to be called is figure 3A. The figures should be re-ordered so that the first one to be called is figure 1.
L217: “possibly as a result attributed increased proximity away from a moisture source”. I do not understand what this means.
L229-231: How do the authors explain the difference between 0.0132Wm-2 and
-0.0035Wm-2
L267: The warmer (than ….) MIS-11c climate
L290-305: The obliquity during MIS-31 is indeed large but it is smaller than during MIS-1 and MIS-5e. The authors indicated large anomalies of insolation but forgot to mention when they occur. They should double check the values provided for temperature anomalies.
L372-374: Is this a result from the models or from the proxy data?
L383: I copied here my earlier comment : “What does ‘annual summer temperature’ refer to?”
L405-406 : According to me it is either one maximum or several maxima. Is there a reference for this statement?
L451: ‘summer temperatures to increase to almost 16°C warmer …’ Is there a reference for this statement?
L459: ‘ the model is missing some important regional processes’. Do the authors have any clue for such missing processes?
Figure 1 : In the caption the reference is the modern orbit while it is the Pre Ind in the figure. They are most probably the same. However, it would be better to be coherent.
Figure 2 : Except for the colour code figure 2 is exactly the same as in Melles et al (2012), although this paper is not acknowledged in the caption. I have a question to the editor and the production. What about the copyright in such a case? My question to the authors is the following. Do they really need this figure in their paper?
Figure 3 : I do not understand the meaning of ‘Pre-Industrial vegetation corresponding to modern summer anomalies’.
Figure 5 : this figure is not cited in the text and should therefore disappear.
Table 2 : the caption should be expanded. The accronyms should be explained.

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RR by Anonymous Referee #2 (27 Mar 2015)

Suggestions for revision or reasons for rejection

The revised manuscript is much improved with the majority of comments/changes suggested in the previous review taken into account. Simulations have been run for longer in order to make sure equilibrium of the surface variables has been reached. The study is now focussed on the comparison of interglacial climates for a specific terrestrial archive during interglacials (with the removal of results relating to glaciation at 2.7Ma) and provides a decent documentation of the results.

Below are suggestions for relatively minor revisions:

The figures need to be re-ordered. For example the first reference to a figure is Figure 5, then Figure 3, then Figure 2 then Figure 1.
Line 83: replace gasses with gases
Line 100: what surface type do you replace the ice sheet with e.g. bare soil, shrub?
Line 115: InterGlaciation change to interglaciation
Line 116: 12-10kyr, do you mean around 14 kyr?
Line 159: Check your units Wm^2 should be Wm^-2
Line 229: Include a reference for carbon dioxide concentration
Line 322: Insert MIS before 31 for clarity
Line 330: Provide a reference for the simulations without vegetation feedbacks
Line 450: The reference provided here only concerns the MIS5e and not interglacials. Furthermore, the simulations with Greenland temperatures greater than 16 Degrees Celsius are those without a Greenland ice sheet used in the coupling methodology and do not actually represent what the Greenland ice sheet was thought to be like at this time.

Figure 5: It is difficult to see the transparent lines (especially when printed). I suggest making this more visible.

It would be worth mentioning in your discussion the issues that arise from comparing data from a core record with output from a climate model in terms of temporal and spatial resolution differences.

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ED: Publish subject to minor revisions (review by Editor) (24 May 2015) by Volker Rath

AR by Anthony J. Coletti on behalf of the Authors (03 Jun 2015) Author's response Manuscript

ED: Publish as is (14 Jun 2015) by Volker Rath

Short summary

Evidence from Pleistocene sediments suggest that the Arctic's climate went through multiple sudden transitions, warming by 2-4 °C (compared to preindustrial times), and stayed warm for hundreds to thousands of years. A climate modelling study of these events suggests that the Arctic's climate and landscape drastically changed, transforming a cold and barren landscape as we know today to a warm, lush, evergreen and boreal forest landscape only seen in the modern midlatitudes.