03.04.2018

# New Publications

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Carlin, Norman; James, Robert A. (2018): Geoengineering Research Under U.S. Law

Carlin, Norman; James, Robert A. (2018): Geoengineering Research Under U.S. Law. In Pratt's Energy Law Report 18 (3), pp. 67–75.

"The authors first divide the techniques under consideration between solar radiation management (aerosols in the stratosphere, or greater white surfaces below) and carbon dioxide removal (ocean iron fertilization (OIF) and other forms of carbon capture and sequestration). They detail the analysis required for an environmental impact statement (EIS) under the National Environmental Policy Act (NEPA), the California Environmental Quality Act (CEQA), and a variety of other U.S. statutes and common-law doctrines. "

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03.04.2018

# New Publications

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MacMartin, Douglas G.; et al. (2018): Solar geoengineering as part of an overall strategy for meeting the 1.5°C Paris target

MacMartin, Douglas G.; Ricke, Katharine L.; Keith, David W. (2018): Solar geoengineering as part of an overall strategy for meeting the 1.5°C Paris target. In Phil. Trans. R. Soc. A 376 (2119), p. 20160454. DOI: 10.1098/rsta.2016.0454.

"We first provide a physical science review of current research, research trends and some of the key gaps in knowledge that would need to be addressed to support informed decisions. Next, since few climate model simulations have considered these limited-deployment scenarios, we synthesize prior results to assess the projected response if solar geoengineering were used to limit global mean temperature to 1.5°C above preindustrial in an overshoot scenario that would otherwise peak near 3°C. While there are some important differences, the resulting climate is closer in many respects to a climate where the 1.5°C target is achieved through mitigation alone than either is to the 3◦C climate with no geoengineering. This holds for both regional temperature and precipitation changes; indeed, there are no regions where a majority of models project that this moderate level of geoengineering would produce a statistically significant shift in precipitation further away from preindustrial levels."

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28.02.2018

# New Publications

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Kleinschmitt, Christoph; et al. (2018): Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO2injection studied with the LMDZ-S3A model

Kleinschmitt, Christoph; Boucher, Olivier; Platt, Ulrich (2018): Sensitivity of the radiative forcing by stratospheric sulfur geoengineering to the amount and strategy of the SO2injection studied with the LMDZ-S3A model. In Atmos. Chem. Phys 18 (4), pp. 2769–2786. DOI: 10.5194/acp-18-2769-2018.

"In this study we use the atmospheric general circulation model LMDZ with the sectional aerosol module S3A to determine how the forcing efficiency depends on the injected amount of SO2, the injection height, and the spatio-temporal pattern of injection. We find that the forcing efficiency may decrease more drastically for larger SO2 injections than previously estimated. As a result, the net instantaneous radiative forcing does not exceed the limit of –2 W m−2 for continuous equatorial SO2 injections and it decreases (in absolute value) for injection rates larger than 20 Tg S yr−1. In contrast to other studies, the net radiative forcing in our experiments is fairly constant with injection height (in a range 17 to 23 km) for a given amount of SO2 injected."

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28.02.2018

# New Publications

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Visioni, Daniele; et al. (2018): Sulfur deposition changes under sulfate geoengineering conditions. Quasi-biennial oscillation effects on the transport and lifetime of stratospheric aerosols

Visioni, Daniele; Pitari, Giovanni; Tuccella, Paolo; Curci, Gabriele (2018): Sulfur deposition changes under sulfate geoengineering conditions. Quasi-biennial oscillation effects on the transport and lifetime of stratospheric aerosols. In Atmos. Chem. Phys 18 (4), pp. 2787–2808. DOI: 10.5194/acp-18-2787-2018.

"Among several possible environmental side effects, the increase in sulfur deposition deserves additional investigation. In this study we present results from a composition–climate coupled model (University of L'Aquila Composition-Chemistry Model, ULAQ-CCM) and a chemistry-transport model (Goddard Earth Observing System Chemistry-Transport Model, GEOS-Chem), assuming a sustained lower-stratospheric equatorial injection of 8 Tg SO2 yr−1. Total S deposition is found to globally increase by 5.2 % when sulfate geoengineering is deployed, with a clear interhemispheric asymmetry (+3.8 and +10.3 % in the Northern Hemisphere (NH) and the Southern Hemisphere (SH), due to +2.2 and +1.8 Tg S yr−1, respectively)."

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18.02.2018

# Media

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Wallstreet Journal: A Big-Sky Plan to Cool the Planet

"Pumping aerosols into the stratosphere may buy us more time, but it’s no substitute for cutting carbon emissions—and we still don’t know enough to do it responsibly."

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10.02.2018

# New Publications

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Jones, Anthony C.; et al. (2018): Regional climate impacts of stabilizing global warming at 1.5 K using solar geoengineering

Jones, Anthony C.; Hawcroft, Matthew K.; Haywood, James M.; Jones, Andy; Guo, Xiaoran; Moore, John C. (2018): Regional climate impacts of stabilizing global warming at 1.5 K using solar geoengineering. In Earth's Future. DOI: 10.1002/2017EF000720.

"In this study, we use a global climate model to investigate the climatic impacts of using solar geoengineering by stratospheric aerosol injection to stabilize global-mean temperature at 1.5 K for the duration of the 21st century against 3 scenarios spanning the range of plausible greenhouse gas mitigation pathways (RCP2.6, RCP4.5, RCP8.5)."

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26.01.2018

# New Publications

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Irvine, Peter J.; et al. (2018): Brief communication. Understanding solar geoengineering's potential to limit sea level rise requires attention from cryosphere experts

Irvine, Peter J.; Keith, David W.; Moore, John (2018): Brief communication. Understanding solar geoengineering's potential to limit sea level rise requires attention from cryosphere experts. In The Cryosphere Discuss., pp. 1–15. DOI: 10.5194/tc-2017-279.

"Stratospheric aerosol geoengineering, a form of solar geoengineering, is a proposal to add a reflective layer of aerosol to the stratosphere to reduce net radiative forcing and so to reduce the risks of climate change. Solar geoengineering could reduce temperatures and so slow melt, but the efficacy of solar geoengineering at offsetting changes to the cryosphere is uncertain. For example, shortwave forcing acts more strongly on the surface than longwave forcing so solar geoengineering would reduce surface melt more effectively but would also suppress the global hydrological cycle potentially reducing accumulation on glaciers."

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20.01.2018

# New Publications

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Gunderson, Ryan; et al. (2018): A Critical Examination of Geoengineering. Economic and Technological Rationality in Social Context

Gunderson, Ryan; Petersen, Brian; Stuart, Diana (2018): A Critical Examination of Geoengineering. Economic and Technological Rationality in Social Context (Sustainability, 10).

"Substantial emissions reductions, unlike geoengineering, are costly, rely more on social-structural than technical changes, and are at odds with the current social order. Because of this, geoengineering will increasingly be considered a core response to climate change. In light of Herbert Marcuse’s critical theory, the promotion of geoengineering as a market-friendly and high-tech strategy is shown to reflect a society that cannot set substantive aims through reason and transforms what should be considered means (technology and economic production) into ends themselves. Such a condition echoes the first-generation Frankfurt School’s central thesis: instrumental rationality remains irrational."

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18.12.2017

# New Publications

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Niemeier, Ulrike; Schmidt, Hauke (2017): Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

Niemeier, Ulrike; Schmidt, Hauke (2017): Changing transport processes in the stratosphere by radiative heating of sulfate aerosols. In Atmos. Chem. Phys 17 (24), pp. 14871–14886. DOI: 10.5194/acp-17-14871-2017.

"The injection of sulfur dioxide (SO2) into the stratosphere to form an artificial stratospheric aerosol layer is discussed as an option for solar radiation management. Sulfate aerosol scatters solar radiation and absorbs infrared radiation, which warms the stratospheric sulfur layer. Simulations with the general circulation model ECHAM5-HAM, including aerosol microphysics, show consequences of this warming, including changes of the quasi-biennial oscillation (QBO) in the tropics. The QBO slows down after an injection of 4 Tg(S) yr−1 and completely shuts down after an injection of 8 Tg(S) yr−1."

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16.11.2017

# New Publications

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Jones, Anthony C.; et al. (2017): Impacts of hemispheric solar geoengineering on tropical cyclone frequency

Jones, Anthony C.; Haywood, James M.; Dunstone, Nick; Emanuel, Kerry; Hawcroft, Matthew K.; Hodges, Kevin I.; Jones, Andy (2017): Impacts of hemispheric solar geoengineering on tropical cyclone frequency. In Nat Comms 8 (1), p. 1382. DOI: 10.1038/s41467-017-01606-0.

"Observations following major volcanic eruptions indicate that aerosol enhancements confined to a single hemisphere effectively modulate North Atlantic tropical cyclone (TC) activity in the following years. Here we investigate the effects of both single-hemisphere and global SAI scenarios on North Atlantic TC activity using the HadGEM2-ES general circulation model and various TC identification methods."

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