Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO<sub>2</sub>injection studied with the LMDZ-S3A model

Kleinschmitt, Christoph; Boucher, Olivier; Platt, Ulrich

doi:https://doi.org/10.5194/acp-18-2769-2018

Articles | Volume 18, issue 4

https://doi.org/10.5194/acp-18-2769-2018

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

Special issue:

The Geoengineering Model Intercomparison Project (GeoMIP):...

https://doi.org/10.5194/acp-18-2769-2018

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

Articles | Volume 18, issue 4

Research article

|

27 Feb 2018

Research article |

| 27 Feb 2018

Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO₂injection studied with the LMDZ-S3A model

Christoph Kleinschmitt, Olivier Boucher, and Ulrich Platt

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Final revised paper (published on 27 Feb 2018)
Preprint (discussion started on 04 Aug 2017)

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Status: closed

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

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SC1: 'Model treatment of atmospheric chemistry', Peer Johannes Nowack, 04 Sep 2017
RC1: 'Review of Kleinschmitt et al.: Important work with limitations', Anonymous Referee #1, 05 Sep 2017
RC2: 'Well-written paper that improves understanding of stratospheric sulfur geoengineering', Anonymous Referee #2, 06 Sep 2017
RC3: 'Review', Anonymous Referee #3, 06 Sep 2017
RC4: 'Review', Anonymous Referee #4, 12 Sep 2017
AC1: 'New PDF file with corrected figure labels available', Christoph Kleinschmitt, 13 Sep 2017

Peer-review completion

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

AR by Christoph Kleinschmitt on behalf of the Authors (28 Nov 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 Dec 2017) by Ulrike Lohmann

RR by Anonymous Referee #3 (14 Dec 2017)

RR by Anonymous Referee #4 (17 Dec 2017)

Suggestions for revision or reasons for rejection

The new version of the paper has improved compared to the previous one. However, a couple of my earlier comments were not sufficiently addressed and are listed again below. Also, a number of new papers have been published that are relevant to this study (see below). The paper would benefit from referring to those as listed below.

Introduction line 24: The authors agree that SAI is not a good abbreviation, but they don’t change it because it is wildly used. I do not agree that this is a good reason for using a misleading abbreviation. Again, the abbreviation should be changed to something like stratospheric aerosol geoengineering.

Page 2, Line 4: “stratospheric aerosol injection” is not correct if the authors are referring to Heckendorn, Niemeier, and English papers.

Page 3,
Line 13: A reference to Richter et al. (2017) would be relevant.
Line 21: Please add a reference to MacMartin et al. (2017), who show that is is more efficient to inject at multiple injection locations outside the equator that at the equator.

Page 7, Line 30: “so the exact ozone feedback is unclear” please remove that sentence and refer for example to Tilmes et al. (2009), who discussed in detail the changes of stratospheric ozone as the result of stratospheric aerosol geoengineering.

Page 9, Line 10ff: Here, you can also refer to Kravitz et al. (2017), who also looked at the same quantities.

Page 10, Line 18: Please also refer to Tilmes et al. (2017), who found very similar results for high vs. low injection cases.

Page 13, line 19ff, and page 15, line 20: A reference to Richter et al. (2017) would be relevant, as well as mentioning difference to the results found in their study.

Line 25: Please note, interactive chemistry has been shown to influence the response of geoengineering to the QBO (Richter et al., 2017).

New publications:
Kravitz, B., MacMartin, D. G., Mills, M. J., Richter, J. H., Tilmes, S., Lamarque, J.-F.,…Vitt, F. (2017). First simulations of designing stratospheric sulfate aerosol geoengineering to meet multiple simultaneous climate objectives. Journal of Geophysical Research: Atmospheres, 122. https://doi.org/10.1002/2017JD026874

Tilmes S., Richter J. H., Mills M. J., Kravitz B., MacMartin D. G., Vitt F.,…Lamarque J.- F. (2017). Sensitivity of aerosol distribution and climate response to stratospheric SO2 injection locations. Journal of Geophysical Research: Atmospheres, 122. https://doi.org/10.1002/2017JD026888

MacMartin, D. G., Kravitz, B., Tilmes, S., Richter, J. H., Mills, M. J., Lamarque, J.-F., Tribbia, J. J., & Vitt, F. (2017). The climate response to stratospheric aerosol geoengineering can be tailored using multiple injection locations. Journal of Geophysical Research: Atmospheres, 122. https://doi.org/10.1002/2017JD026868

Richter, J. H., Tilmes, S., Mills, M. J., Tribbia, J., Kravitz, B., MacMartin, D. G.,…Jean-Francois, L. (2017). Stratospheric dynamical response and ozone feedbacks in the presence of SO2 injections. Journal of Geophysical Research: Atmospheres, 122. https://doi.org/10.1002/2017JD026912

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RR by Anonymous Referee #2 (18 Dec 2017)

ED: Publish subject to minor revisions (review by editor) (21 Dec 2017) by Ulrike Lohmann

AR by Christoph Kleinschmitt on behalf of the Authors (11 Jan 2018) Author's response Manuscript

ED: Publish as is (15 Jan 2018) by Ulrike Lohmann

AR by Christoph Kleinschmitt on behalf of the Authors (17 Jan 2018)

Short summary

We use a state-of-the-art stratospheric aerosol model to study geoengineering through stratospheric sulfur injections. We find that the efficiency may decrease more drastically for larger injections than previously estimated and that injections at higher altitude are not more effective. This study may provide additional evidence that this proposed geoengineering technique is still more complicated, probably less effective, and may implicate stronger side effects than initially thought.

Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO2injection studied with the LMDZ-S3A model

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Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO₂injection studied with the LMDZ-S3A model