Rapid and reliable assessment of methane impacts on climate

Ocko, Ilissa B.; Naik, Vaishali; Paynter, David

doi:https://doi.org/10.5194/acp-18-15555-2018

Articles | Volume 18, issue 21

https://doi.org/10.5194/acp-18-15555-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/acp-18-15555-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 18, issue 21

Research article

|

30 Oct 2018

Research article |

| 30 Oct 2018

Rapid and reliable assessment of methane impacts on climate

Ilissa B. Ocko, Vaishali Naik, and David Paynter

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Final revised paper (published on 30 Oct 2018)
Preprint (discussion started on 24 Jan 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 Ocko et al. 10.5194/acp-2018-26', Anonymous Referee #1, 06 Feb 2018
SC1: 'Comment on a valuable comparison of simple & complex models', Marcus Sarofim, 24 Apr 2018
RC2: 'Review of Ocko et al', Anonymous Referee #2, 25 Apr 2018
AC1: 'Authors response to referee and short comments', Ilissa Ocko, 23 Jul 2018

Peer-review completion

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

AR by Ilissa Ocko on behalf of the Authors (23 Jul 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (25 Jul 2018) by Patrick Jöckel

RR by Anonymous Referee #1 (15 Aug 2018)

Suggestions for revision or reasons for rejection

I thank the authors for their effective response to the earlier review comments. I find the revised paper to be much better structured and much clearer, especially regarding the role of unforced variability. Subject to some minor technical corrections/suggestions, which will only take minutes to implement, I am happy to recommend it for publication.

1. I have been rather sensitised by a comment from another reviewer to the fact that this paper should not be seen to specifically endorse MAGICC (as it can be read to be doing so in several places) but more generally endorse the use of reduced complexity models, of which MAGICC is just one. So for example, at 1:21 it would be better written as "reduced complexity models such as MAGICC", and similarly at 4:8-9, 13:18-19 and 14:20.

2. In their response to my original comment 11:21, the authors said they would note that MAGICC is not open source. They say they have acted on this, but I couldnt find where they had done so (unless it is the cryptic (to some) statement that the executable is available (14:26)). For some people, this is a major limitation of using MAGICC because, frankly, one doesnt fully know what is really in it. I suggest that in the "limitations" around 5:27 and again at 14:25 this issue is explicitly noted. It may help to encourage the custodians of MAGICC to enter the 21st century!

3. At 6:10 the authors say that the ECS is higher than MAGICC, but as I understand, it is in the range of the calibration models - so strictly it is higher than the MAGICC median and mean? This could be usefully clarified.

4. Regarding my original 6-15 (I dont think this really needs acting on, as it is arguably "geeks corner") I still do not understand why MAGICC needs methane radiative efficiencies. It uses the methane radiative forcing expression, and these efficiencies are implicit in that expression. It could be that it only uses them to compute the impact of ozone change on methane.

5. My original comment 8-28 suggested removing "independent" as these temperature datasets are certainly not independent. The authors seemed to concur in their response, but "independent" is still there in the text.

Minor - can be picked up at proof stage

3:17 "Raper"
5:21 "homogenEous"
8:21 The equations are a bit jumbled (two on the same line) at least in my printed version.
7:17 missing closing parenthesis
8:25 and 29 Some subscripting and superscripting needed
A few of the references are concatenated with theprevious one (Collins et al. 2016, Delworth et al. 2016)

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RR by Anonymous Referee #3 (20 Aug 2018)

ED: Publish subject to minor revisions (review by editor) (03 Sep 2018) by Patrick Jöckel

AR by Ilissa Ocko on behalf of the Authors (13 Sep 2018) Author's response Manuscript

ED: Publish as is (17 Sep 2018) by Patrick Jöckel

AR by Ilissa Ocko on behalf of the Authors (18 Sep 2018)

Short summary

As communities worldwide analyse options to reduce methane emissions from energy use, agriculture, and waste management, there is an immediate need to build confidence in rapid assessment tools other than standard climate metrics – which misrepresent impacts over all timescales. In this paper, we show that a simplified climate model can easily and rapidly provide scientifically robust climate responses to changes in methane emissions, thereby improving mitigation analysis and decision-making.