29.07.2019

# New Publications

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Gruber, S.; et al. (2019): A Process Study on Thinning of Arctic Winter Cirrus Clouds With High‐Resolution ICON‐ART Simulations

Gruber, S.; Blahak, U.; Haenel, F.; Kottmeier, C.; Leisner, T.; Muskatel, H. et al. (2019): A Process Study on Thinning of Arctic Winter Cirrus Clouds With High‐Resolution ICON‐ART Simulations. In: J. Geophys. Res. Atmos. 498 (21), S. 339. DOI: 10.1029/2018JD029815.

"In this study, cloud‐resolving simulations of a case study for a limited area of the hibernal Arctic were performed with the atmospheric modeling system ICON‐ART (ICOsahedral Nonhydrostatic‐Aerosol and Reactive Trace gases). A thorough comparison with data both from satellite as well as aircraft measurement is presented to validate the simulations. In addition, the model is applied to clarify the microphysical processes occurring when introducing artificial aerosol particles into the upper troposphere with the aim of modifying cirrus clouds in the framework of climate engineering."

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30.06.2019

# New Publications

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Bock, L.; et al. (2019): Contrail cirrus radiative forcing for future air traffic

Bock, L.; Burkhardt, U. (2019): Contrail cirrus radiative forcing for future air traffic. In: Atmos. Chem. Phys 19 (12), S. 8163–8174. DOI: 10.5194/acp-19-8163-2019.

"The climate impact of air traffic is to a large degree caused by changes in cirrus cloudiness resulting from the formation of contrails. Contrail cirrus radiative forcing is expected to increase significantly over time due to the large projected increases in air traffic. We use ECHAM5-CCMod, an atmospheric climate model with an online contrail cirrus parameterization including a microphysical two-moment scheme, to investigate the climate impact of contrail cirrus for the year 2050."

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30.09.2018

# Media

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livemint: Opinion | The risk of planetary geoengineering

"In 1991, when Mount Pinatubo in the Philippines erupted, it spewed over 20 million tonnes of sulphur into the upper atmosphere. Shortly thereafter we began to witness a strange phenomenon. The sulphates in the stratosphere were acting as a sort of a sun visor, shielding the earth from the sun’s rays and reducing global temperatures by nearly half a degree Celsius by the end of the year."

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25.07.2017

# New Publications

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Cao, Long; et al. (2017): Simultaneous stabilization of global temperature and precipitation through cocktail geoengineering

Cao, Long; Duan, Lei; Bala, Govindasamy; Caldeira, Ken (2017): Simultaneous stabilization of global temperature and precipitation through cocktail geoengineering. In Geophys. Res. Lett. 37 (D6), p. 117. DOI: 10.1002/2017GL074281.

"Here we investigate the possibility of stabilizing both global mean temperature and precipitation simultaneously by combining two geoengineering approaches: stratospheric sulfate aerosol increase (SAI) that deflects sunlight to space and cirrus cloud thinning (CCT) that enables more longwave radiation to escape to space."

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24.07.2017

# Media

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Newsweek: Climate Change and Geoengineering: Artificially Cooling Planet Earth by Thinning Cirrus Clouds

"Over recent decades, scientists from across the globe have been discussing the potential of geoengineering—the deliberate manipulation of the environment that could, in theory, cool the planet and help stabilize the climate."

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24.07.2017

# Media

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Live Science: Cool the Planet? Geoengineering Is Easier Said Than Done

""If cirrus clouds behave like a blanket around the Earth, you're trying to get rid of that blanket," Lohmann, a professor of experimental atmospheric physics at ETH Zurich, told Live Science."

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22.07.2017

# New Publications

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Lohmann, Ulrike; Gasparini, Blaž (2017): A cirrus cloud climate dial?

Lohmann, Ulrike; Gasparini, Blaž (2017): A cirrus cloud climate dial? In: Science (New York, N.Y.) 357 (6348), S. 248–249. DOI: 10.1126/science.aan3325.

"Climate engineering through cirrus cloud thinning, in contrast, mainly targets the long-wave radiation that is emitted from Earth."

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14.06.2017

# New Publications

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Lauvset, Siv K.; et al. (2017): Climate engineering and the ocean. Effects on biogeochemistry and primary production

Lauvset, Siv K.; Tjiputra, Jerry; Muri, Helene (2017): Climate engineering and the ocean. Effects on biogeochemistry and primary production. In: Biogeosciences Discuss., S. 1–36. DOI: 10.5194/bg-2017-235

"Here we use an Earth System Model with interactive biogeochemistry to project future ocean biogeochemistry impacts from large-scale deployment of three different radiation management (RM) climate engineering (also known as geoengineering) methods: stratospheric aerosol injection (SAI), marine sky brightening (MSB), and cirrus cloud thinning (CCT). We apply RM such that the change in radiative forcing in the RCP8.5 emission scenario is reduced to the change in radiative forcing in the RCP4.5 scenario. The resulting global mean sea surface temperatures in the RM experiments are comparable to those in RCP4.5, but there are regional differences."

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02.02.2017

# New Publications

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Kärcher, Bernd (2017): Cirrus Clouds and Their Response to Anthropogenic Activities

Kärcher, Bernd (2017): Cirrus Clouds and Their Response to Anthropogenic Activities. In: Curr Clim Change Rep. DOI: 10.1007/s40641-017-0060-3.

"This review assesses recent observational and modeling evidence of how anthropogenic activities might affect cirrus. Changes in physical properties and chemical composition of liquid aerosol particles will unlikely affect cirrus significantly, but anthropogenic influences may occur through changes in heterogeneous ice nuclei."

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19.11.2016

# New Publications

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Quaas, Johannes; et al. (2016): Regional climate engineering by radiation management: Prerequisites and prospects

Quaas, Johannes; Quaas, Martin F.; Boucher, Olivier; Rickels, Wilfried (2016): Regional climate engineering by radiation management: Prerequisites and prospects. In Earth’s Future. DOI 10.1002/2016EF000440.

"In this paper, we discuss the idea that RM can be differentiated and scaled in several dimensions with potential objectives being to influence a certain climate parameter in a specific region. Some short-lived climate forcers (e.g., tropospheric aerosols) exhibit strong geographical and temporal variability, potentially leading to limited- area climate responses. Marine cloud brightening and thinning or dissolution of cirrus clouds could be operated at a rather local scale."

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