Reconstructing geographical boundary conditions for palaeoclimate modelling during the Cenozoic

Baatsen, Michiel; van Hinsbergen, Douwe J. J.; von der Heydt, Anna S.; Dijkstra, Henk A.; Sluijs, Appy; Abels, Hemmo A.; Bijl, Peter K.

doi:https://doi.org/10.5194/cp-12-1635-2016

Articles | Volume 12, issue 8

https://doi.org/10.5194/cp-12-1635-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/cp-12-1635-2016

© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 12, issue 8

Research article

|

11 Aug 2016

Research article |

| 11 Aug 2016

Reconstructing geographical boundary conditions for palaeoclimate modelling during the Cenozoic

Michiel Baatsen, Douwe J. J. van Hinsbergen, Anna S. von der Heydt, Henk A. Dijkstra, Appy Sluijs, Hemmo A. Abels, and Peter K. Bijl

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Final revised paper (published on 11 Aug 2016)
Supplement to the final revised paper
Preprint (discussion started on 21 Oct 2015)
Supplement to the preprint

Interactive discussion

Status: closed

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

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- Supplement

RC C2134: 'Review of Baatsen et al., A Generalised Approach to Reconstructing geographical Boundary Conditions for Palaeoclimate Modelling', R. Dietmar Müller, 27 Oct 2015
- AC C3104: 'Response to Referee: R.D. Mueller', Michiel Baatsen, 01 Feb 2016
RC C2774: 'review of "A Generalised Approach to Reconstructing geographical Boundary Conditions for Palaeoclimate Modelling"', Matthew Huber, 28 Dec 2015
- AC C3108: 'Response to Referee: M. Huber', Michiel Baatsen, 01 Feb 2016

Peer-review completion

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

ED: Reconsider after major revisions (12 Feb 2016) by André Paul

AR by Michiel Baatsen on behalf of the Authors (24 Mar 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (31 Mar 2016) by André Paul

RR by Dietmar Müller (13 Apr 2016)

Suggestions for revision or reasons for rejection

The authors have improved this version of the paper somewhat, but there are still a number of problems to be addressed. The most severe problem is that the workflow presented in this paper in no way represents a generalised approach for producing paleobathymetry grids, as many ad hoc fixes used in the 38 Ma reconstructions are custom-designed just for reconstructing this time, especially when it comes to mixing different vintages of rotation models, paleo-age and paleo-depth grids. The current title “A Generalised Approach to Reconstructing geographical Boundary Conditions for Palaeoclimate Modelling” is misleading. The paper would be acceptable if solely focussed on the 38 Ma reconstruction. I therefore suggest a change of the title of the paper to:

Reconstructing Geographical Boundary Conditions for Palaeoclimate Modelling at 38 Ma

Some specific comments:

There is a mismatch between using the present-day age-grid from Seton et al. 2012, and the paleobathymetry from Muller et al. 2008, since the present-day age grid for 2012 is based on the reconstruction history/rotations of that model, which differs significantly, especially for the Pacific (Manihiki/Hikurangi breakup).

This new workflow uses the Crosby et al. (2006) age-depth relationship, to convert the reconstructed age grid into depth. But the Muller 2008 paleobathymetry grid, which they use for filling gaps in their initial paleobathymetry reconstruction based on the Seton et al. (2012) present-day agegrid, is based on Stein and Stein’s (1992) age-depth relationship, and also has sediments added. So mixing different age-depth relationships and sediment cover (vs. no sediment cover) in the Baatsen workflow certainly does not represent a sensible generic workflow for constructing paleobathymetry grids., even if this works reasonably well for 38 Ma.

Some comments by line:

Line 42: Not sure what "poorly constrained and/or in agreement" means.

Line 62: "transition" in Eocene-Oligocene Transition is capitalised (earlier, line 34, it isn't).

Line 69: "require" is misspelt

Line 87: Seton et al., 2012 isn't a Phanerozoic model.

Lines 90-91: It is insufficiently justified to what extent a paleomagnetic reference frame is better suited for paleoclimate reconsrtructions, even if this is obvious theoretically. How different it is from other reference frames for 38 Ma in terms of paleolatitude? Is there a reference for this?

Lines 114-136: This entire paragraph is hard to follow.

Line 133: Is there a reference for the robustness for continental shelf margins through time?

Workflow – I couldn’t get this to work very well – it crashed after producing Figure 5. Exporting the files exactly as needed for the matlab script is extremely tedious, and not suitable for any sort of generic workflow.

Exporting files as a png. (step 1 and 2): I can now see why the authors didn't export a netcdf file directly – they are reconstructing polygons (gpml), not a grid, and GPlates can't convert polygons to grids. Nevertheless, this step would be much better completed using GMT for this to become generic and easier to use (e.g. exporting reconstructed polygons, and using a combination of grdmask and grdmath steps).

For part 2., there are numerous files needed, with specific colours (from the Apple palette, which Windows users will not have!). These files seem to be specific for 38 Ma (their reconstruction time) – again this is no generic recipe.

Step 5: I don’t really follow what is happening with rotating the grids here, and I found it convoluted to get this step to work.

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ED: Publish subject to minor revisions (review by Editor) (13 May 2016) by André Paul

AR by Michiel Baatsen on behalf of the Authors (30 May 2016) Author's response Manuscript

ED: Publish subject to minor revisions (review by Editor) (15 Jun 2016) by André Paul

AR by Michiel Baatsen on behalf of the Authors (20 Jun 2016) Author's response Manuscript

ED: Publish as is (23 Jun 2016) by André Paul

AR by Michiel Baatsen on behalf of the Authors (30 Jun 2016)

Short summary

One of the major difficulties in modelling palaeoclimate is constricting the boundary conditions, causing significant discrepancies between different studies. Here, a new method is presented to automate much of the process of generating the necessary geographical reconstructions. The latter can be made using various rotational frameworks and topography/bathymetry input, allowing for easy inter-comparisons and the incorporation of the latest insights from geoscientific research.