Solar irradiance reduction to counteract radiative forcing from a quadrupling of CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;: climate responses simulated by four earth system models

Schmidt, Hauke; Alterskjær, Kari; Karam, Diana Bou; Boucher, Oliviér; Jones, Anthony C.; Kristjansson, J. E.; Niemeier, Ulrike; Schulz, Mıchael; Aaheim, Asbjørn; Benduhn, François; Lawrence, M. G.; Timmreck, Claudia

doi:10.5194/esd-3-63-2012

Cited by 155 publications

(236 citation statements)

References 41 publications

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“…Similar patterns occur in simulations of mean temperatures under both GHG warming scenarios 5 and under geoengineering scenarios (Schmidt et al, 2012;Curry et al, 2014;Kravitz et al, 2013b). Pithan and Mauritsen (2014) conclude that in climate models it is primarily the temperature feedback with surface albedo of secondary importance in producing Arctic amplification under GHG forcing.…”

Section: Spatial Response In Extremessupporting

confidence: 52%

“…This feature was noted for non-extreme indices in the G1 experiments analyzed by Schmidt et al (2012) and Kravitz et al (2013b). In contrast, the index for G4-rcp45 ( Fig.3f) is near-zero though slightly negative on the whole, with the multi-model mean value of -1.8±0.9 mm.…”

mentioning

confidence: 90%

“…In order to compare the impacts of the two SRM methods, we also made use of the corresponding outputs from piControl, abrupt4×CO2, and rcp45. We exclude the first decade following the large increase in forcing in common with other authors (Schmidt et al, 2012;Curry et al 2014), and base our analysis on 40 years of data. All G1 and abrupt4×CO2 simulations are analyzed over 15 a common period of simulation years 11 to 50, and the G4 and rcp45 simulations are analyzed from year 2030 to 2069.…”

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confidence: 99%

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Extreme temperature and precipitation response to solar dimming and stratospheric aerosol geoengineering

Ji¹,

Fang²,

Curry³

et al. 2018

Preprint

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Abstract. We examine extreme temperature and precipitation under two potential geoengineering methods forming part of the Geoengineering Model Intercomparison Project (GeoMIP). The solar 25 dimming experiment G1 is designed to completely offset the global mean radiative forcing due to a CO2-quadrupling experiment (abrupt4×CO2), while in GeoMIP experiment G4, the radiative forcing due to the representative concentration pathway 4.5 (RCP4.5) scenario is partly offset by a simulated layer of aerosols in the stratosphere. Both G1 and G4 geoengineering simulations lead to lower maximum temperatures at higher latitudes, and on land primarily through feedback effects involving high latitude 30 processes such as snow cover, sea ice and soil moisture. Maximum 5-day precipitation increases over subtropical oceans, whereas warm spells decrease markedly in the tropics, and the number of consecutive dry days decreases in most deserts. The precipitation during the tropical cyclone (hurricane) seasons becomes less intense, whilst the remainder of the year becomes wetter. Aerosol injection is more effective 2 than dimming in moderating extreme precipitation (and flooding), possibly due to stratospheric warming by aerosol injection working in tandem with sea surface temperature reductions to moderate extreme tropical storm cyclogenesis. The differences in the response of temperature extremes between the two types of geoengineering are relatively minor. Despite the magnitude of the radiative forcing applied in G1 being ~6.5 times larger than in G4, and differences in the aerosol chemistry and transport schemes 5 amongst the models, one can discern clear differences in the precipitation extremes between the types of geoengineering probably due to the aerosol direct effect and related energetic changes.

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Section: Spatial Response In Extremessupporting

confidence: 52%

mentioning

confidence: 90%

mentioning

confidence: 99%

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Extreme temperature and precipitation response to solar dimming and stratospheric aerosol geoengineering

Ji¹,

Fang²,

Curry³

et al. 2018

Preprint

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“…The global mean radiative forcing in the GLOBAL case is negative (~−0.67 Wm −2 ) as the efficacy of solar forcing is only about 80% (Modak et al 2016) and consequently more solar irradiance reduction is required to nearly compensate the warming in the 2XCO2 case ( Fig. 2d; Table 2; Schmidt et al 2012).…”

Section: Residual Global Climate Changementioning

confidence: 99%

Effects of Arctic geoengineering on precipitation in the tropical monsoon regions

2017

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due to Arctic geoengineering, but there is still a residual precipitation increase (up to 7%) in most monsoon regions associated with the residual CO 2 induced warming in the tropics. The ITCZ shift due to our Global geoengineering simulation, where aerosols (20 Mt) are prescribed uniformly around the globe, is much smaller and the precipitation changes in most monsoon regions are within ±2% as the residual CO 2 -induced warming in the tropics is also much less than in Arctic and Polar geoengineering. Further, global geoengineering nearly offsets the Arctic warming. Based on our results we infer that Arctic geoengineering leads to ITCZ shift and leaves residual CO 2 induced warming in the tropics resulting in substantial precipitation decreases (increases) in the Northern (Southern) hemisphere monsoon regions.

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“…Such surface cooling is intended but numerical CE studies show that the artificial climate under CE would not be the same as a natural one under the same radiative forcing conditions (Schmidt et al, 2012), because, e.g. CE changes the hydrological cycle Kravitz et al, 2013) due to different effects on top of the atmosphere (TOA) and surface radiation ).…”

Section: Introductionmentioning

confidence: 99%

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

2017

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Abstract. The injection of sulfur dioxide (SO 2 ) 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 . Transport of species in the tropics and subtropics depends on the phase of the QBO. Consequently, the heated aerosol layer not only impacts the oscillation of the QBO but also the meridional transport of the sulfate aerosols. The stronger the injection, the stronger the heating and the simulated impact on the QBO and equatorial wind systems. With increasing injection rate the velocity of the equatorial jet streams increases, and the less sulfate is transported out of the tropics. This reduces the global distribution of sulfate and decreases the radiative forcing efficiency of the aerosol layer by 10 to 14 % compared to simulations with low vertical resolution and without generated QBO. Increasing the height of the injection increases the radiative forcing only for injection rates below 10 Tg(S) yr −1 (8-18 %), a much smaller value than the 50 % calculated previously. Stronger injection rates at higher levels even result in smaller forcing than the injections at lower levels.

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Solar irradiance reduction to counteract radiative forcing from a quadrupling of CO<sub>2</sub>: climate responses simulated by four earth system models

Cited by 155 publications

References 41 publications

Extreme temperature and precipitation response to solar dimming and stratospheric aerosol geoengineering

Extreme temperature and precipitation response to solar dimming and stratospheric aerosol geoengineering

Effects of Arctic geoengineering on precipitation in the tropical monsoon regions

Changing transport processes in the stratosphere by radiative heating of sulfate aerosols

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