Better perhaps to adjust bunker fuel sulphur. Jason Blackstock (cc) did some excellent work on this, which I don't think got published.
Presently the trend is for desulphurisation of marine bunker fuel, giving perfectly sensible port air quality improvements. This is, I understand, now the subject of legislation. However, in the deep ocean, these sulphur cuts result in measurable global warming. Simply replacing the bunker fuel sulphur for open ocean use would potentially be helpful. I hope there's some research on this in the literature, but presently I'm unaware of any. A On 5 Aug 2014 20:45, "Alan Robock" <rob...@envsci.rutgers.edu> wrote: > Dear Mike, > > I don't understand this suggestion. Because of the shorter sulfate > lifetime than in the stratosphere (even if it is more than the 1 week you > get for surface injections), you would require a much larger sulfur > injection for the same radiative forcing as compared to the stratosphere, > and a much larger resulting acid deposition in remote areas. And how could > you be guaranteed to maintain the emissions from a lot of stacks from small > enterprises that would keep changing over time based on business variations > and local environmental laws? This seems to be a much riskier strategy > even than stratospheric injections from a centralized operation. > > And why would you think most removal would be in the ITCZ? That would > require the sulfate to enter the ITCZ from the surface in specific tropical > regions. > > Alan > > Alan Robock, Distinguished Professor > Editor, Reviews of Geophysics > Director, Meteorology Undergraduate Program > Department of Environmental Sciences Phone: +1-848-932-5751 > Rutgers University Fax: +1-732-932-8644 > 14 College Farm Road E-mail: rob...@envsci.rutgers.edu > New Brunswick, NJ 08901-8551 USA http://envsci.rutgers.edu/~robock > http://twitter.com/AlanRobock > Watch my 18 min TEDx talk at http://www.youtube.com/watch?v=qsrEk1oZ-54 > > On 8/5/2014 2:39 PM, Mike MacCracken wrote: > > Regarding this proposal for sustaining the sulfate cooling influence, the > suggestion on this that I have been making for several years (see refs > below, among others) is similar: rather than having a relatively high > sulfate loading concentrated over populated areas, inject SO2 above the > boundary layer (important to promote a longer lifetime) to create thinner > sulfate layers over much larger remote areas of the ocean (e.g., over the > Pacific and Indian Oceans), hoping to promote both clear sky and cloudy sky > brightness. Doing this over the ocean would take advantage of its low > albedo so that the sulfates would not be offsetting reflected solar > radiation from the surface. Doing this over larger areas and at lower > loadings would tend to moderate the change in energy in a given area, > although there would need to be testing of this. Most removal might come in > ITCZ rains, mostly over the ocean. > > Mike MacCracken > > > MacCracken, M. C., 2009: Beyond Mitigation: Potential Options for > Counter-Balancing the Climatic and Environmental Consequences of the Rising > Concentrations of Greenhouse Gases, Background Paper to the 2010 World > Development Report, Policy Research Working Paper (RWP) 4938, The World > Bank, Washington, DC, May 2009, 43 pp. > > MacCracken, M. C., 2009: On the possible use of geoengineering to moderate > specific climate change impacts, *Environmental Research Letters*, *4* > (October-December 2009) 045107 doi:10.1088/1748-9326/4/4/045107 [ > http://www.iop.org/EJ/article/1748-9326/4/4/045107/erl9_4_045107.html]. > > MacCracken, M. C., 2011: Potential Applications of Climate Engineering > Technologies to Moderation of Critical Climate Change Impacts, IPCC Expert > Meeting on Geoengineering, 20-22 June 2011, Lima, Peru, pages 55-56 in > Meeting Report, edited by O. Edenhofer, R. Pichs-Madruga, Y. Sokona, C. > Field, V. Barros, T. F. Stocker, Q. Dahe, J. Minx, K. Mach, G.-K. Plattner, > S. Schlömer, G. Hansen, and M. Mastrandrea, Intergovernmental Panel on > Climate Change, Geneva, Switzerland. > > > > On 8/1/14 8:53 AM, "ecologist" <ecologi...@gmail.com> wrote: > > Currently, anthropogenic tropospheric aerosols present both Dr Jekyll > and Mr Hyde faces. > > On the one hand, tropospheric aerosols play an important role on climate, > with a net cooling radiative forcing effect. > On the other hand, tropospheric aerosols affect terrestrial ecosystems and > human health and are associated with increased heart, lung and respiratory > diseases, which lead to disablement and numerous premature human deaths > (Shindell et al, 2012). > > Consequently, reducing anthropogenic tropospheric aerosols emissions, on > the one hand will lead to a positive forcing (warming) at local and > regional scale, and on the other hand will save numerous lives and > significantly reduce health costs. > > *What is proposed is to investigate means whereby the cooling effect of > current emissions is kept unchanged and their deleterious effects are > reduced,* using only modifications of existing industrial aerosols > emitters. Key advantages of such investigations are that they avoid most of > the roadblocks associated with SRM. > So, what is proposed is a Win-Win research program that will at the same > time allow indirect geoengineering research, and reduce tropospheric > pollution. > > *(Important remark: it is not proposed to perform CCS, or CDR). * > This is so, because the current anthropogenic tropospheric sulphate > aerosol emissions are estimated to be *almost two orders of magnitude > larger* than requested by Stratospheric Particle Injection geoengineering > schemes to offset the effects of a 2 X CO2 (carbon dioxide concentration > doubling in the atmosphere). > Thus the strategy to reduce current sulphate *tropos*pheric emissions and > at the same time to keep their current cooling effects will be like > performing indirect climate engineering without the need to artificially > inject sulphates in the *strato*sphere. > > Now, the radiative forcing due to sulphate aerosols is estimated to be > -0.4 W/m2 with a range of -0.2 to -0.8 W/m2. > On a global average basis, the sum of direct and indirect radiative > forcing at the top of atmosphere by anthropogenic aerosols is estimated to > be -1.2 W/m2 [-2.4 to -0.6 W/m2] (*cooling*) over the period of 1750 - > 2000. This is significant when compared to the positive (*warming*) > forcing of +2.63 [±0.26] W/m2 by anthropogenic long-lived greenhouse gases > over the same period [Forster et al., 2007]. > In heavily polluted regions, aerosol cooling overwhelms greenhouse warming > [Ramanathan et al., 2001; Li et al., 2010]. > > The tropospheric aerosol lifetimes are approximately 1 to 2 weeks, which > is quite shorter. Therefore, these current human made aerosols have an > uneven distribution, both horizontally and vertically, and are more > concentrated near their source regions over continents and in the boundary > layer. > > *Emission reductions of aerosols in the troposphere will lead to a > positive forcing (warming), unless the sulphates lifetimes are increased > and their horizontal and vertical distribution are improved. Whilst the > particulates are removed, some part of the sulphates can be lofted higher > to where they can act as a solar-reflective shield to cool larger regions. * > To do so, what is proposed is to model the effects of a theoretical > fivefold aerosols emission reduction (80% removal of sulphates, NOx, and > > 95% removal of soot, black carbon, ash…) by adding filters or electrostatic > precipitators to the flue stack of a majority of fossil fuel fired power > plants, for adequate particulate filtering and scrubbing, and *at the > same time increasing the height release of sulphates for a reduced number > of other power plant stacks in order to allow these (20% SOx) emissions to > over pass the boundary layer and stay longer in the atmosphere*. > > This can be performed by the use of taller chimneys allowing the flue > gases to pass the boundary layer, so that the impact of a regional emission > reduction is not confined to the region itself, by allows intercontinental > transport (long-range transport) of these sulphates *produced by existing > anthropogenic aerosols*. > Several other possibilities exist to increase the height release and > dilution of gas emissions from flue stacks. > > This strategy was proposed in page 818-819 of an *open access article* > http://www.sciencedirect.com/science/article/pii/S1364032113008460 > Fighting global warming by climate engineering. > > > > * Two figures are attached to summarize this research proposal * > Public perception of SRM climate engineering is often presented as Ulysses > choices between the perils of Scylla and Charybdis, despite the very good > cooling potential to mitigate global warming, and the high effectiveness > and accessibility of geoengineering schemes consisting of the stratospheric > injection of sulphate aerosols. > The Win-Win strategy proposed here may change this perception at the same > time as helping to advance CE research... > > > Renaud de_Richter, PhD > http://www.solar-tower.org.uk/ > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to geoengineering+unsubscr...@googlegroups.com. > To post to this group, send email to geoengineering@googlegroups.com. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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