Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution to Resolve a Policy Dilemma?

By P. Crutzen. 2006

1,487 citations recorded by the source corpus.

Fossil fuel burning releases about 25 Pg of CO2 per year into the atmosphere, which leads to global warming (Prentice et al., 2001). However, it also emits 55 Tg S as SO2 per year (Stern, 2005), about half of which is converted to sub-micrometer size sulfate particles, the remainder being dry deposited. Recent research has shown that the warming of earth by the increasing concentrations of CO2 and other greenhouse gases is partially countered by some backscattering to space of solar radiation by the sulfate particles, which act as cloud condensation nuclei and thereby influence the micro-physical and optical properties of clouds, affecting regional precipitation patterns, and increasing cloud albedo (e.g., Rosenfeld, 2000; Ramanathan et al., 2001; Ramaswamy et al., 2001). Anthropogenically enhanced sulfate particle concentrations thus cool the planet, offsetting an uncertain fraction of the anthropogenic increase in greenhouse gas warming. However, this fortunate coincidence is “bought” at a substantial price. According to the World Health Organization, the pollution particles affect health and lead to more than 500,000 premature deaths per year worldwide (Nel, 2005). Through acid precipitation and deposition, SO2 and sulfates also cause various kinds of ecological damage. This creates a dilemma for environmental policy makers, because the required emission reductions of SO2, and also anthropogenic organics (except black carbon), as dictated by health and ecological considerations, add to global warming and associated negative consequences, such as sea level rise, caused by the greenhouse gases. In fact, after earlier rises, global SO2 emissions and thus sulfate loading have been declining at the rate of 2.7% per year, potentially explaining the observed reverse from dimming to brightening in surface solar radiation at many stations worldwide (Wild et al., 2005). The corresponding increase in solar radiation by 0.10% per year from 1983 to 2001 (Pinker et al., 2005) contributed to the observed climate warming during the past decade. According to model calculations by Brasseur and Roeckner (2005), complete improvement in air quality could lead to a decadal global average surface air temperature increase by 0.8 K on most continents and 4 K in the Arctic. Further studies by Andreae et al. (2005) and Stainforth et al. (2005) indicate that global average climate warming during this century may even surpass the highest values in the projected IPCC global warming range of 1.4–5.8 ◦C (Cubasch et al., 2001). By far the preferred way to resolve the policy makers’ dilemma is to lower the emissions of the greenhouse gases. However, so far, attempts in that direction have

Subfields: Atmospheric Science, Global and Planetary Change

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Citations in the corpus

Stratospheric Aerosol Injection as a Deep Reinforcement Learning Problem (2019, methodology): “Stratospheric aerosol injection (SAI), which reflects incoming solar radiative forcing and thus can be used to offset excess radiative forcing due to the greenhouse effect, is widely regarded as one of the most technically and economically feasible methods (Crutzen, 2006; MacMartin, 2014; Smith, 201”
Ocean acidification: the other CO2 problem. (2009, background): “Geo-engineering solutions that attempt to slow global warming without reducing atmospheric CO2 concentration, such as injection of stratospheric aerosols (Crutzen 2006), will not reduce ocean acidification.”
Stratospheric ozone response to sulfate geoengineering: Results from the Geoengineering Model Intercomparison Project (GeoMIP) (2014, methodology): “, SO2) into the stratosphere [Budyko, 1974; Crutzen, 2006].”
Cost analysis of stratospheric albedo modification delivery systems (2012, positive): “calculations we have conformed to the analysis of Pierce et al (2010) that release rate should be of order 0.”
Public understanding of solar radiation management (2011, background): “The taboo was broken in 2006 when Paul Crutzen published an editorial essay urging more systematic consideration of SRM (Crutzen 2006).”
An overview of the Earth system science of solar geoengineering (2016, background): “The particles would scatter and reflect solar radiation, increasing the planetary reflectivity (albedo), and cooling the climate.(6) There are a number of other potentially effective solar geoengineering proposals that are not as well understood as SAI.”
THE EXTRATROPICAL UPPER TROPOSPHERE AND LOWER STRATOSPHERE (2011, background): “Mitigation of anthropogenic radiative forcing through “ planetary radiation management ” (or “ geoengineering ” ) [ Crutzen , 2006] could potentially be implemented through enhancement of the stratospheric aerosol layer [ Tilmes et al. , 2009].”
The impact of abrupt suspension of solar radiation management (termination effect) in experiment G2 of the Geoengineering Model Intercomparison Project (GeoMIP) (2013, background): “, the deliberate brightening of the planet in order to reflect additional sunlight back to space to counteract greenhouse gas induced warming, has been suggested as a plausible countermeasure [e.g., Mautner, 1991; Crutzen, 2006].”
Geoengineering: Encouraging Research and Overseeing Implementation (2006, background): “Paul Crutzen (2006) analyzes the idea of intentionally injecting sulfur into the stratosphere, to enhance the albedo of Earth, so as to slow the warming of the planet due to greenhouse gases.”
Climate-Resilient Pathways: Adaptation, Mitigation, and Sustainable Development (2014, background): “Discussions of geoengineering have only recently become an active area of discourse in science, despite a longer history of efforts to modify climate (Schneider, 1996, 2008; Keith, 2000; Crutzen, 2006).”
“Sunshade World”: A fully coupled GCM evaluation of the climatic impacts of geoengineering (2008, methodology): “Various schemes have been proposed, including the injection of sulphate aerosols into the atmosphere [Crutzen, 2006] and increasing carbon sinks through oceanic iron fertilisation [Martin, 1990].”
Climate policy under uncertainty: a case for solar geoengineering (2013, neutral): “Changes in mean global temperature, T—measured in • C—are defined as a linear function of radiative forcing, R: T = λR (2) where λ is the climate sensitivity parameter with units • C m”
Stratospheric geoengineering impacts on El Niño/Southern Oscillation (2015, background): “This has forced a recent consideration of geoengineering: intentional manipulation of global-scale physical processes (Crutzen, 2006).”