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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08.11.2017

# New Publications

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Mills, Michael J.; et al. (2017): Radiative and chemical response to interactive stratospheric sulfate aerosols in fully coupled CESM1(WACCM)

Mills, Michael J.; Richter, Jadwiga H.; Tilmes, Simone; Kravitz, Ben; MacMartin, Douglas G.; Glanville, Anne A. et al. (2017): Radiative and chemical response to interactive stratospheric sulfate aerosols in fully coupled CESM1(WACCM). In J. Geophys. Res. Atmos. DOI: 10.1002/2017JD027006.

"We present new insights into the evolution and interactions of stratospheric aerosol using an updated version of the Whole Atmosphere Community Climate Model (WACCM). Improved horizontal resolution, dynamics, and chemistry now produce an internally generated quasi-biennial oscillation, and significant improvements to stratospheric temperatures and ozone compared to observations. We present a validation of WACCM column ozone and climate calculations against observations. "

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08.11.2017

# New Publications

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Tilmes, Simone; et al. (2017): Sensitivity of aerosol distribution and climate response to stratospheric SO2 injection locations

Tilmes, Simone; Richter, Jadwiga H.; Mills, Michael J.; Kravitz, Ben; MacMartin, Douglas G.; Vitt, Francis et al. (2017): Sensitivity of aerosol distribution and climate response to stratospheric SO2 injection locations. In J. Geophys. Res. Atmos. DOI: 10.1002/2017JD026888.

"Here, we use CESM1(WACCM) to explore the impact of continuous single grid point SO2 injections at 7 different latitudes and 2 altitudes in the stratosphere on aerosol distribution and climate. For each of the 14 locations, 3 different constant SO2 emission rates were tested to identify linearity in aerosol burden, aerosol optical depth, and climate effects. We found that injections at 15° N and 15° S and at 25 km altitude have equal or greater effect on radiation and surface temperature than injections at the equator."

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08.11.2017

# New Publications

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Richter, Jadwiga H.; et al. (2017): Stratospheric Dynamical Response and Ozone Feedbacks in the Presence of SO2 Injections

Richter, Jadwiga H.; Tilmes, Simone; Mills, Michael J.; Tribbia, Joseph J.; Kravitz, Ben; MacMartin, Douglas G. et al. (2017): Stratospheric Dynamical Response and Ozone Feedbacks in the Presence of SO2 Injections. In J. Geophys. Res. Atmos. DOI: 10.1002/2017JD026912.

"We explore here the stratospheric dynamical response to sulfur dioxide injections ∼ 5 km above the tropopause at multiple latitudes (equator, 15° S, 15° N, 30° S and 30° N) using a fully coupled Earth system model, Community Earth System Model, version 1, with the Whole Atmosphere Community Climate Model as its atmospheric component (CESM1(WACCM)). We find that in all simulations, the tropical lower stratosphere warms primarily between 30° S and 30° N, regardless of injection latitude."

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08.11.2017

# New Publications

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Kravitz, Ben; et al. (2017): First simulations of designing stratospheric sulfate aerosol geoengineering to meet multiple simultaneous climate objective

Kravitz, Ben; MacMartin, Douglas G.; Mills, Michael J.; Richter, Jadwiga H.; Tilmes, Simone; Lamarque, Jean-Francois et al. (2017): First simulations of designing stratospheric sulfate aerosol geoengineering to meet multiple simultaneous climate objectives. In J. Geophys. Res. Atmos. DOI: 10.1002/2017JD026874.

"We describe the first simulations of stratospheric sulfate aerosol geoengineering using multiple injection locations to meet multiple simultaneous surface temperature objectives. Simulations were performed using CESM1(WACCM), a coupled atmosphere-ocean general circulation model with fully interactive stratospheric chemistry, dynamics (including an internally generated quasi-biennial oscillation), and a sophisticated treatment of sulfate aerosol formation, microphysical growth, and deposition."

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