Thursday, January 21, 2016

Tropospheric Sulfur Emission Geoengineering. A Conjecture.

By Oscar A. Escobar
Florida, USA – Gt. January 21, 2016
CC BY-NC 4.0
Last Updated 1/27/2016

Most of the studies available to the public about sulfur injection as a method of SRM climate geoengineering focus on the stratosphere.  But a large gap in public information, if not knowledge, exist in regards to the possibility of tropospheric sulfur injection (or emission, rather) as a method for climate engineering; even though the concept has been expressed, as the following book excerpt states:[1]

Geoengineering: Sulfur as Savior?
A tone of desperation is palpable in climate-change science when well-known people seriously propose that filling the stratosphere with sulfur dioxide may be the only way to stop run-away greenhouse warming. Do we really want to pump the stratosphere full of sulfur to shroud the surface from warmth, then live in a perpetual acid mist? Paul J. Crutzen of the Max Planck Institute for Chemistry in Germany, who won a Nobel Prize in 1995 for showing how industrial gases damage the Earth's ozone shield, advanced the idea anew in 2006, citing the "grossly disappointing international political response" to increasing evidence of global warming (Kerr 2006d, 401).
"We should treat these ideas like any other research and get into the mind-set of taking them seriously," said Ralph J. Cicerone, president of the National Academy of Sciences (Broad 2006). Most of these proposals involve geoengineering, large-scale rearranging of the Earth's environment to suit human needs. This idea "should not be taken as a license to go out and pollute," Cicerone said, emphasizing that most scientists believe that reducing greenhouse gases in the atmosphere should be the top priority. He added, however, that "Pin my opinion, he [Crutzen] has written a brilliant paper" (Broad 2006). Wallace S. Broecker, a geoengineering pioneer at Columbia University, also has proposed spreading tons of sulfur dioxide into the stratosphere, as erupting volcanoes occasionally do. The injections, he calculated in the 1980s, would require a fleet of hundreds of jumbo jets and, as a by-product, would increase acid rain (Broad 2006).
In a draft of his paper, Crutzen estimated the annual cost of his sulfur proposal at up to $50 billion, or about 5 percent of the world's annual military spending. "Climatic engineering, such as presented here, is the only option available to rapidly reduce temperature rises" if international efforts fail to curb greenhouse gases, Crutzen wrote. "So far," he added, "there is little reason to be optimistic" (Broad 2006). Supporters of this idea contend that any increase in sulfur at the Earth's surface would be small compared with the tons already being emitted from the smokestacks of coal-fueled plants (Broad 2006). Another proposed solution along the same lines involves the burning of sulfur in ships and power plants to form sulfate aerosols.

The possibility of this type of tropospheric geoengineering “unintended” or otherwise, has also been raised most recently by Oliver Morton in his book The Planet Remade: How Geoengineering Could Change the World:[2]

But some of the mid-ocean sulphur comes from ships, and thus so does some planetary cooling. It has been calculated that the new emission standards the IMO is bringing into force this decade will reduce the cooling effects of global pollution by something like a third of a watt per square metre – a considerably greater effect, models would suggest, than that of all the carbon dioxide emitted by every generator and engine in the world over the same ten years. Those new standards will also, according to a companion analysis, save something in the region of 40,000 lives a year, because what is emitted over the mid-oceans does not stay over the mid-oceans; it is blown to shore, where it increases the damage done by pollution to susceptible lungs.
Do I think it realistic to imagine that the IMO might, as the result of a far-reaching envelope-stretching boundary-breaking debate, have come to a Crutzen-like grand bargain in which it sought to make good the cooling it was taking away by implementing a replacement brightening? Not really; but it remains striking – no, shocking – that as far as I can ascertain no one even mentioned the matter, even though the IMO’s own technical advisers used the term ‘geoengineering’ in some of their analyses. Conversations have to start somewhere, and that would have been a good place to start one.

An even more recent, presentation by Chuck Long from the US National Oceanic and Atmospheric Administration NOAA,  at the 2015 fall meeting of the American Geophysical Union AGU, titled “A23K-04: Evidence of Clear-Sky Daylight Whitening: Are we already conducting geoengineering?”.[3] The presentation focused on the direct and indirect effects of aviation aerosols seems, in my view, to strengthen the concept of “Tropospheric Sulfur Injection as (unintended) geoengineering”. The presentation abstract reads:

Long et al. (2009, JGR 114) analyzed surface radiation data spanning 1995 through 2007 from several ARM and six SURFRAD sites across the continental US, and showed an average 8 Wm-2/decade brightening in all-sky downwelling SW. The study also showed a 5 Wm-2/decade increase in the clear-sky downwelling SW, an expected result of decreasing aerosol optical depths during the same time period (Augustine et al., 2008, JGR 113). However, the unexpected result of the Long et al. study is that the 5 Wm-2/decade increase occurred in the diffuse SW, while the direct SW remained virtually unchanged...opposite what is expected for aerosol direct effect due to decreases in aerosols. With detailed radiative transfer modeling and correlation with US FAA commercial flight hours through the same years, Long et al. suggested that while the decreased aerosols did increase the total SW, an increase in high, sub-visual contrail-generated ice haze repartitioned the increase into the diffuse SW component through large-mode particle scattering.
Subsequent attempts to investigate the veracity of this speculation using long time series of ARM Micropulse and Raman lidars data proved untenable due to instrument limitations and continuity issues. However, similar to using the red/blue ratio of pixel color amounts in processing color sky images to infer clouds, we have used clear-sky diffuse SW irradiance measurements from the Multi-Frequency Rotating Shadowband Radiometer (MFRSR) 870, 500, and 415 nm spectral channels to look at any possible trends suggesting "whitening" of the cloud-free skies over the ARM SGP site. We will present our preliminary findings to date of these investigations suggesting indeed that there has been an aggregate "whitening" of the sky conditions we typically consider to be "cloud free."
Augustine, J.A., G.B.Hodges, E.G.Dutton, J.J. Michalsky, and C.R.Cornwall (2008), An aerosol optical depth climatology for NOAA’s national surface radiation budget network (SURFRAD), J. Geophys. Res., 113, D11204, doi:10.1029/2007JD009504.
Long, C. N., E. G. Dutton, J. A. Augustine, W. Wiscombe, M. Wild, S. A. McFarlane, and C. J. Flynn (2009): Significant Decadal Brightening of Downwelling Shortwave in the Continental US, JGR, 114, D00D06, doi:10.1029/2008JD011263.

This presentation garnered what seems to be very limited press coverage,[4] and virtually nonexistent reaction from civil society and environmental activists. Strange… given the controversial and pugnacious nature of the various debates surrounding the topic of geoengineering, particularly when it refers to climate justice, environmental concerns and moral hazard issues.
A short online debate has been documented in the ‘Geoengineering Google Group’,[5] mostly centering on the definition of geoengineering, and whether or not the known effects of human industrial emissions could represent geoengineering. Chuck long is quoted:[6]

“Chuck Long, from the US National Oceanic and Atmospheric Administration (Noaa), said that if his thinking was correct then what was occurring was an example of "accidental geoengineering".
"If you look up the definition of geoengineering, it includes large-scale manipulation of parts of the climate system or the environment, and I believe this ice haze from jet traffic does satisfy that requirement," he told reporters.”

On January 19, 2016, Slate magazine in partnership with New America, and Arizona State University on emerging technologies, public policy, and society; conducted a short online forum titled “These 2 Experts Will Answer Your Burning Geoengineering Questions”.[7]  The two experts were Jeff Goodell a “contributing editor at Rolling Stone, a fellow at New America, and the author of How to Cool the Planet: Geoengineering and the Audacious Quest to Fix Earth’s Climate.” And “Raymond T. Pierrehumbert, who is the Halley professor of physics at the University of Oxford and has called geoengineering “barking mad.””

Here is the question I submitted and the answer by Raymond T. Pierrehumbert:

Question: How is the geoengineering debate impacted, in terms of climate justice, environment, moral hazard and research, by the following two facts? 1) A recent presentation by Chuck Long at the American Geophysical Union fall meeting argues that aviation emissions has been responsible for a form of ongoing SRM "accidental geoengineering." 2) Current anthropogenic annual sulfur emission are higher than five times the sulfur emitted by Mt. Pinatubo in 1991, and are currently emitted mostly in the Northern Hemisphere, with 98 vs. 6 Tg S year.

Pierrehumbert: This isn’t “geoengineering.” These sort of effects are no different from other inadvertent things we do that affect the climate, including both greenhouse gas emissions, and emissions of sulfate pollution that form reflecting droplets in the atmosphere (aerosols). These are by-products of things we want to do (like fly, burn coal, etc.). Geoengineering, (or better “climate intervention”) is reserved for the case where the climate effect is not an inadvertent by-product, but rather the aim itself. By the way, sulfur dioxide injection is what’s proposed for albedo hacking that is done in the stratosphere, but the amount you’d need to inject over the ocean surface to cause a significant cloud change there makes even the geoengineering boosters blanche. For that reason, the proposals for low-level cloud modification generally involve sea-salt rather than sulfur dioxide. Still a bad idea, but we have to keep the actual scientific facts straight.
Speaking of blanching… I had included this reference to the “98 vs. 6 Tg S year” figures in my question, but it was omitted from the published version:

Approaches to Observe Anthropogenic Aerosol-Cloud Interactions, Johannes Quaas, 2015.[8]

Although Mr. Pierrehumbert’s answer is very interesting. It does not resonate with me particularly because his statement “By the way, sulfur dioxide injection is what’s proposed for albedo hacking that is done in the stratosphere” may not be entirely accurate, as I have documented. But to the question of whether we are geoengineering or not, the best answer I have seen so far is the following:

“The question about geoengineering was interesting to me, because in some ways none of us would be here if in fact we weren’t already geoengineering this planet, that is the whole reason we are worried about it. The fact that we may have not intended to do it, the fact that we didn’t think about it rationally, ethically, nor was it part of our design; that is relatively immaterial from the point of view of the systems involved in the planet. It’s a geoengineered planet.”[9]  Brad R. Allenby

Coming back to the original title of this article, “Tropospheric Sulfur Emission Geoengineering. A Conjecture”, I think that it would be helpful to investigate what proper scientific proposals of that sort may look like.  I imagine some may not be too different from what “we” are currently doing trough global aviation and shipping emissions. But that may also bring some very uncomfortable epiphanies.  No doubt a strong reason for some to continue to prefer barking mad ignorance.

And just in case… do I think deploying climate geoengineering is a good idea, and the only way to sustainable growth? No, particularly because I believe there are economic and energy alternatives to the fossil fuel economy that do not include ‘degrowth’!

But nevertheless one of the safest ways to know is… knowledge trough research.


A free acces model study about tropospheric ("In the set of model experiments considered here, we directly inject sulfate aerosols at a single model level at 12.1 km") emissions as geoengineering. Follow the link for the full study in pdf:
Could aerosol emissions be used for regional heat wave mitigation?
D. N. Bernstein1,2, J. D. Neelin2, Q. B. Li2, and D. Chen21Department of Soil and Water Sciences, Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, POB 12, Rehovot 76100, Israel
2Department of Atmospheric and Oceanic Sciences, University of California, Los Angeles, 405 Hilgard Ave., Los Angeles, CA 90095, USA
doi:10.5194/acp-13-6373-2013Abstract. Geoengineering applications by injection of sulfate aerosols into the stratosphere are under consideration as a measure of last resort to counter global warming. Here a potential regional-scale application to offset the impacts of heat waves is critically examined. Using the Weather Research and Forecasting model with fully coupled chemistry (WRF-Chem), the effect of regional-scale sulfate aerosol emission over California in each of two days of the July 2006 heat wave is used to quantify potential reductions in surface temperature as a function of emission rates in a layer at 12 km altitude. Local meteorological factors yield geographical differences in surface air temperature sensitivity. For emission rates of approximately 30 μg m−2 s−1 of sulfate aerosols (with standard WRF-Chem size distribution) over the region, temperature decreases of around 7 °C result during the middle part of the day over the Central Valley, one of the areas hardest hit by the heat wave. Regions more ventilated with oceanic air such as Los Angeles have slightly smaller reductions. The length of the hottest part of the day is also reduced. Advection effects on the aerosol cloud must be more carefully forecast for smaller injection regions. Verification of the impacts could be done via measurements of differences in reflected and surface downward shortwave. Such regional geoengineering applications with specific near-term target effects but smaller cost and side effects could potentially provide a means of testing larger scale applications. However, design considerations for regional applications, such as a preference for injection at a level of relatively low wind speed, differ from those for global applications. The size of the required injections and the necessity of injection close to the target region raise substantial concerns. The evaluation of this regional-scale application is thus consistent with global model evaluations, emphasizing that mitigation via reduction of fossil fuels remains preferable to considering geoengineering with sulfate aerosols.

[1] Johansen, Bruce E., (2009-11-03) The Encyclopedia of Global Warming Science and Technology (Pg 270-271), Greenwood.

[2] Morton, Oliver (2015-11-03) The Planet Remade: How Geoengineering Could Change the World (p. 296), Princeton University Press. Google Play, U.S. Edition.

[3] AGU Fall Meeting, 2015, A23K-04: Evidence of Clear-Sky Daylight Whitening: Are we already conducting geoengineering? - Retrieved online on January 21, 2016 from

[4] Kiel, 2015 December 26, [press review] Media responses to Charles Long on "Unintentional Geoengineering" - Retrieved online on January 21, 2016 from

[5] Rau, G. (2015, December 16) "Accidental" Geoengineering? [Blog topic] Retrieved online January 21, 2016 from!topic/geoengineering/2AASwDEgumg

[6] Amos Jonathan, 2015 December 16, Jet traffic linked to ice haze, Retrieved online on January 21, 2016 from

[7] Slate (2015 January 19) These Two Experts Answered Your Burning Geoengineering Questions, Retrieved online on January 21, 2016 from

[8] Quaas, J. (2015) Approaches to Observe Anthropogenic Aerosol-Cloud Interactions. Springer Link. Retrieved online on January 21, 2016 from

[9] Allenby, B. R. (2007, October 9) Earth Systems Engineering and Management, MIT Video. Retrieved online on July 7, 2013 from
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A #Geoengineering #Climate Issues blog - Geoingeniería by Oscar and Jocelyn Escobar is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.Licencia Creative Commons
A #Geoengineering #Climate Issues blog por Oscar y Jocelyn Escobar se distribuye bajo una Licencia Creative Commons Atribución-NoComercial 4.0 Internacional.