Global rules for translating land-use change (LUH2) to land-cover change for CMIP6 using GLM2

Ma, Lei; Hurtt, George C.; Chini, Louise P.; Sahajpal, Ritvik; Pongratz, Julia; Frolking, Steve; Stehfest, Elke; Klein Goldewijk, Kees; O'Leary, Donal; Doelman, Jonathan C.

doi:https://doi.org/10.5194/gmd-13-3203-2020

Articles | Volume 13, issue 7

https://doi.org/10.5194/gmd-13-3203-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Coupled Model Intercomparison Project Phase 6 (CMIP6) Experimental...

https://doi.org/10.5194/gmd-13-3203-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 13, issue 7

Model description paper

|

14 Jul 2020

Model description paper |

| 14 Jul 2020

Global rules for translating land-use change (LUH2) to land-cover change for CMIP6 using GLM2

Lei Ma, George C. Hurtt, Louise P. Chini, Ritvik Sahajpal, Julia Pongratz, Steve Frolking, Elke Stehfest, Kees Klein Goldewijk, Donal O'Leary, and Jonathan C. Doelman

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Final revised paper (published on 14 Jul 2020)
Supplement to the final revised paper
Preprint (discussion started on 17 Jul 2019)
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

RC1: 'review of luh2 translation paper', Anonymous Referee #1, 21 Aug 2019
- AC1: 'Answer to Reviewer 1', lei ma, 05 Dec 2019
RC2: 'Review of Global Transition Rules for Translating Land-use Change (LUH2) To Land-cover Change for CMIP6 using GLM2', Eddy Robertson, 23 Aug 2019
- AC2: 'Answer to Reviewer 2', lei ma, 05 Dec 2019
RC3: 'Review mamuscript Global Transition Rules for Translating Land-use Change (LUH2) To Land-cover Change for CMIP6 using GLM2', Anonymous Referee #3, 16 Sep 2019
- AC3: 'Answer to Reviewer 3', lei ma, 05 Dec 2019

Peer-review completion

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

AR by Lei Ma on behalf of the Authors (05 Dec 2019) Author's response Manuscript

ED: Referee Nomination & Report Request started (18 Jan 2020) by Andrew Yool

RR by Anonymous Referee #3 (31 Jan 2020)

RR by Anonymous Referee #1 (07 Feb 2020)

Suggestions for revision or reasons for rejection

Review of gmd-2019-146 revision:
Global rules for translating land-use change (LUH2) to land-cover change for CMIP6 using GLM2

Summary
This is a revision of a previously reviewed manuscript. The authors have done a good job addressing the reviewer comments (which was not a trivial task), but there are still a few things that need clarification before publication. I don’t have any major concerns. Please see the comments below for details.

Specific comments/suggestions:

Introduction

page 3, lines 19-23:
It isn’t clear what “inconsistent land-cover translation” means here. Inconsistent with LUH? Inconsistent across ESMs/DGVMs?
It seems that the meaning here is leaning toward inconsistency across ESMs/DGVMs, but both inconsistencies are relevant. So I suggest clearly specifying both.
And “globally consistent” is also ambiguous. A rule that is global in spatial extent? Or a rule that is applied consistently by different folks around the globe? Again, it seems like the latter makes more sense here. That it is a global rule is different issue that also generates uncertainty.
Also, “eliminate added uncertainties” is an overly ambitious claim.
Maybe try “Consistent application of a specified rule for translating…could reduce uncertainties from translation inconsistencies in studying…”

Methodology

page 4, lines 14-16:
Please clarify the relationship to LUH2. These GLM2 runs generate and track the exact same LUH2 data as before, and the additional translational tracking does not affect the LUH2 land use transitions. The translation and tracking of vegetation carbon is an additional capacity.

page 5, lines 17-20
Does this mean that the constant spin-up climate is a 100-year average?
How were the stocks and fluxes calculated during the translation simulations?
Did the spin-up produce a spatial, but temporally static, look-up table for use by the simulations, or was it just for initial conditions?
Or are the simulations also driven by some form of static or time-varying climate that determines carbon fluxes and stocks?
It appears later on page 7 that the spinup contributes to parameters for eq. 7. This should be clarified here.

page 5, line 30
Is the type of vegetation remaining in the land use categories (5-8) tracked? Or is it just the biomass value that characterizes the vegetation?
Is it assumed that land use categories have no biomass (and no change over time in biomass) if the vegetation has been cleared (this is answered on page 10)?

page 6, lines 11-14
Is this correct for gamma? It seems like it should be the opposite: a 1 value for “O” such that the land use type gains vegetation when no clearing occurs. Clearing means that no vegetation would be gained.

page 7, lines 3-4
This needs clarification, as gamma isn’t the same as for the reverse of transitions to land use categories. For example, any transition to land use from primary or secondary would generate a loss of vegetation in primary or secondary land, regardless of clearing, which would mean that gamma is always one for eq. 5; the lost vegetation fraction would either be in a land use category, or it has been cleared.

Results

page 11, line 12
reference table 4

page 11, line 13
I suggest being specific here, as table 4 shows the results. You don’t need the e.g. clause, and you should state that 5 of 8 countries have values within range for rules 1-3 and 4 out of 8 for rule 4 (if i counted correctly)

page 11, line 16
It isn’t clear what you mean here by larger difference and what these differences are. I assume you mean differences between rules 1-3 and rule 4.

page 12, line 22
I am not sure that this metric evaluates the heterogeneity. I suggest something like “…best capture carbon density globally…)

Discussions and Conclusions

page 13, lines 10-11
I suggest rephrasing rangeland part, as currently it isn’t clear what the rule does when establishing rangeland. Rather than switching to leaving vegetation, state that for rangeland the rule clears all vegetation only if source land is forest.

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ED: Publish subject to minor revisions (review by editor) (21 Feb 2020) by Andrew Yool

AR by Lei Ma on behalf of the Authors (07 Apr 2020) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (23 Apr 2020) by Andrew Yool

Dear Authors,

Thank you for your revised manuscript and responses to referees.

I have examined both now but am unable to make a complete assessment because some of your responses to Referee #3 are unclear. In particular, several do not clearly articulate the resulting changes to the manuscript (or even if any were made).

I have attached a version of your response with mark-up to indicate where I am unclear about your response. I do not think that any are substantive, but would appreciate some extra clarity so that I am certain that the referee’s comments have been satisfactorily addressed or dismissed.

If you have any questions, please feel free to get in contact with me. I apologise for this additional delay, but I wish to be certain that the points raised by the referees have been clearly resolved.

Separately, when reviewing your revised submission I did note a few minor issues, and have listed these below. Please amend these so that your manuscript can proceed to the production phase.

Thank you again for your patience with the review process. And I hope that this message finds you and your families safe and in good health.

With best regards,

Andrew Yool.

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Abstract: tweak sentence to: “Our analysis shows that this rule is one of three (out of nine) rules that produce comparable estimates of forest cover, vegetation carbon and emissions to independent estimates, and also mitigate the anomalously high carbon emissions from land-use change observed in previous studies in the 1950s.”

Abstract, pg. 2, ln. 1: formatting of units requires correction

Introduction, pg. 3, ln. 5: tweak to “double the conversion rate of the 40s or 60s”

Pg. 4, ln. 20: “850AD” is referred to, while other dates do note use this date label (in any case, “CE” might be preferred)

Comments to the Author: PDF

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AR by Lei Ma on behalf of the Authors (24 Apr 2020) Author's response Manuscript

ED: Publish subject to technical corrections (01 May 2020) by Andrew Yool

AR by Lei Ma on behalf of the Authors (19 May 2020) Author's response Manuscript

Short summary

Earth system models require information on historical land cover change. We present transition rules to generate land cover change from newly developed land use dataset (Land-use Harmonization, LUH2). The resulting forest cover, vegetation carbon, and emissions from land use and land cover change are simulated and evaluated against remote sensing data and other studies. The rules can guide the incorporation of land-cover information within earth system models for CMIP6.