Weakened tropical circulation and reduced precipitation in response to geoengineering

Ferraro, Angus J.; Highwood, Eleanor J.; Charlton‐Perez, Andrew

doi:10.1088/1748-9326/9/1/014001

Cited by 87 publications

(108 citation statements)

References 30 publications

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“…We note that Equatorial drying under a similar geoengineering scenario has also been reported in (Ferraro et al, 2014).…”

supporting

confidence: 76%

“…However, the body of the presently available scientific analysis, albeit increasing (Lenton and Vaughan, 2013;Ferraro et al, 2014), is yet lacking the consideration of many more crucial aspects of the problem. For example, ours is the first attempt to conceptually categorize and frame geoengineering in terms of response theory (Kubo, 1966;Ruelle, 2009) and the theory of nonautonomous dynamical systems (Sell, 1967a, b;Romeiras et al, 1990;Crauel and Flandoli, 1994;Crauel et al, 1997;Arnold, 1998;Kloeden and Rasmussen, 2011;Carvalho et al, 2013), and then in turn as an inverse problem.…”

Section: Introductionmentioning

confidence: 99%

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Critical Assessment of Geoengineering Strategies using Response Theory

Bódai

Lucarini

Lunkeit³

2018

Preprint

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Abstract. We investigate in an intermediate-complexity climate model (I) the applicability of linear response theory to assessing a geoengineering method, and (II) the success of the considered method. The geoengineering problem is framed here as a special optimal control problem, which leads mathematically to the following inverse problem. A given rise in carbon dioxide concentration [CO 2 ] would result in a global climate change with respect to an appropriate ensemble average of the surface air temperature [T s ] . We are looking for a suitable modulation of solar forcing which can cancel out the said global change, 5 or modulate it in some other desired fashion. It is rather straightforward to predict this solar forcing, considering an infinite time period, by linear response theory, and we will spell out an iterative procedure suitable for numerical implementation that applies to finite time periods too.Regarding (I), we find that under geoengineering, i.e. the combined greenhouse and solar forcing, the actual response ∆ [T s ] asymptotically is not zero, indicating that the linear susceptibility is not determined correctly. This is due to a significant 10 quadratic nonlinearity of the response under system identification achieved by a forced experiment. This nonlinear contribution can in fact be easily removed, which results in much better estimates of the linear susceptibility, and, in turn, in a five-fold reduction in ∆ [T s ] under geoengineering. Regarding (II), however, we diagnose this geoengineering method to result in a considerable spatial variation of the surface temperature anomaly, reaching more than 2 [K] at polar/high latitude regions upon doubling the [CO 2 ] concentration, even in the ideal case when the geoengineering method was successful in canceling out the 15 response in the global mean. In the same time, a new climate is realised also in terms of e.g. an up to 4 [K] cooler tropopause or drier/disrupted Tropics, relative to unforced conditions.

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“…We note that Equatorial drying under a similar geoengineering scenario has also been reported in (Ferraro et al, 2014).…”

supporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Critical Assessment of Geoengineering Strategies using Response Theory

Bódai

Lucarini

Lunkeit³

2018

Preprint

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“…However, some of these early studies also suggested quite negative regional implications of some scenarios of deployment and were interpreted as evidence for legitimate equity concerns. Findings included, for example, that solar geoengineering had ''the potential to drive regional climates outside the envelope of greenhouse gas-induced warming, creating ''novel'' conditions'' (Irvine et al 2010: L18702); that solar geoengineering might weaken the Indian monsoon (Robock 2012); involve a large reduction in precipitation (Ferraro et al 2014;Tilmes et al 2013); or involve tradeoffs in which there would inevitably be winners and losers (Ricke et al 2010).…”

Section: Equity As Distributional Outcomes: Winners and Losers In Solmentioning

confidence: 99%

Evoking equity as a rationale for solar geoengineering research? Scrutinizing emerging expert visions of equity

Flegal

Gupta

2017

Int Environ Agreements

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This paper examines how notions of equity are being evoked by expert advocates of more research into solar geoengineering. We trace how specific understandings of equity figure centrally-although not always explicitly-in these expert visions. We find that understandings of equity in such ''vanguard visions'' are narrowly conceived as epistemic challenges, answerable by (more) scientific analysis. Major concerns about equity are treated as empirical matters, requiring scientific assessment of feasibility, risks, or ''win-win'' distributive outcomes and optimizations, with concurrent calls to delimit risk or reduce scientific uncertainties. We argue that such epistemic framings sidestep, inter alia, the inequality in resources available to diverse non-experts-including the ''vulnerable'' evoked in expert visions-to project their own equity perspectives onto imagined technological pathways of the future. These may include concerns relating to moral or historical responsibility and/or lack of agency in shaping the directions of innovation. We conclude that the performative power and political implications of specific expert visions of equity, evoked as a rationale to undertake solar geoengineering research, require continued scrutiny.

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“…There are mainly two causes for the changes in the global mean precipitation. One cause is the temperature change (Bony et al, 2013;Ferraro et al, 2014;Kravitz et al, 2013b), which inflicts a feedback response due to the increased humidity in the atmosphere. The second mechanism is the temperature-independent atmospheric forcing (the change in the radiation between the surface and the top of the atmosphere) (Ferraro et al, 2014;Ferraro and Griffiths 2016).…”

Section: The Global Mean Temperature and Precipitation Responsementioning

confidence: 99%

“…One cause is the temperature change (Bony et al, 2013;Ferraro et al, 2014;Kravitz et al, 2013b), which inflicts a feedback response due to the increased humidity in the atmosphere. The second mechanism is the temperature-independent atmospheric forcing (the change in the radiation between the surface and the top of the atmosphere) (Ferraro et al, 2014;Ferraro and Griffiths 2016). This is the rapid adjustment that occurs in a short timescale, when the change in the radiative balance is compensated by the changes in the latent and sensible heat fluxes (Bala et al, 2008).…”

Section: The Global Mean Temperature and Precipitation Responsementioning

confidence: 99%

Radiative and climate effects of stratospheric sulfur geoengineering using seasonally varying injection areas

et al. 2017

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Abstract. Stratospheric sulfur injections have often been suggested as a cost-effective geoengineering method to prevent or slow down global warming. In geoengineering studies, these injections are commonly targeted to the Equator, where the yearly mean intensity of the solar radiation is the highest and from where the aerosols disperse globally due to the Brewer-Dobson Circulation. However, compensating for greenhouse gas-induced zonal warming by reducing solar radiation would require a relatively larger radiative forcing to the mid-and high latitudes and a lower forcing to the low latitudes than what is achieved by continuous equatorial injections. In this study we employ alternative aerosol injection scenarios to investigate if the resulting radiative forcing can be targeted to be zonally more uniform without decreasing the global the mean radiative forcing of stratospheric sulfur geoengineering. We used a global aerosol-climate model together with an Earth system model to study the radiative and climate effects of stratospheric sulfur injection scenarios with different injection areas. According to our simulations, varying the SO 2 injection area seasonally would result in a similar global mean cooling effect as injecting SO 2 to the Equator, but with a more uniform zonal distribution of shortwave radiative forcing. Compared to the case of equatorial injections, in the seasonally varying injection scenario where the maximum sulfur production from injected SO 2 followed the maximum of solar radiation, the shortwave radiative forcing decreased by 27 % over the Equator (the latitudes between 20 • N and 20 • S) and increased by 15 % over higher latitudes. Compared to the continuous injections to the Equator, in summer months the radiative forcing was increased by 17 and 14 % and in winter months decreased by 14 and 16 % in Northern and Southern hemispheres, respectively. However, these forcings do not translate into as large changes in temperatures. The changes in forcing would only lead to 0.05 K warmer winters and 0.05 K cooler summers in the Northern Hemisphere, which is roughly 3 % of the cooling resulting from solar radiation management scenarios studied here.

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Weakened tropical circulation and reduced precipitation in response to geoengineering

Cited by 87 publications

References 30 publications

Critical Assessment of Geoengineering Strategies using Response Theory

Critical Assessment of Geoengineering Strategies using Response Theory

Evoking equity as a rationale for solar geoengineering research? Scrutinizing emerging expert visions of equity

Radiative and climate effects of stratospheric sulfur geoengineering using seasonally varying injection areas

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