Dear Michael, Dear All, Our proposal concerns mainly "current tropospheric anthropogenic sulfate emissions". Global "man made" annual SO2 emissions were 143 Tg SO*2* in 2008 (Huneeus, N. 2013), and the radiative forcing due to sulphate aerosols is estimated to be −0.4 W/m2*. * Incidentally, we also suggested to remove particles (soot, BC, ash...), because it is cheaper to remove the dust (with an electrostatic filter) from the smoke coming out of industrial chimneys, than wash the exhaust air flux with alkaline agents (in order to remove NOx, or SOx). Could you please consider again the* win-win proposal* which was to *clean the air without warming the planet!* Cheers Renaud
Le samedi 2 août 2014 23:09:04 UTC+2, Michael Hayes a écrit : > > Renaud and Oliver Morton et. al., > > I need to apologize for misrepresenting Dr. Solomon's work (apologies also > extended to her) in that the work she did on atmospheric water vapor level > reduction did not cover the* cause* of the 10% reduction over a decade > (the paper is attached below). Around the same time frame that her paper > was published another paper detailed the rapid increase in the construction > of coal fired power plants in China during the same time frame (2000-2009) > of the (Solomon et. al) observed reduction in water vapor and it was that > second paper which focused upon the BC/S wetting issue. I seem to have > mentally linked the two papers. > > The issue of BC/S wetting potentially being able to significantly reduce > atmospheric water vapor levels is not a robustly studied area. However, one > paper which gives a good primer on one aspect of the wetting chemistry is > offered below. > > The enhanced oxidation of SO2 by NO2 on carbon particulates > <http://www.sciencedirect.com/science/article/pii/0004698180900888> > > - Wesley R. Cofer III > <http://www.sciencedirect.com/science/article/pii/0004698180900888#>, > - David R. Schryer > <http://www.sciencedirect.com/science/article/pii/0004698180900888#>, > - Robert S. Rogowski > <http://www.sciencedirect.com/science/article/pii/0004698180900888#> > - > > Abstract > > - > > *"The oxidation of SO2 on carbon particles in dry air and in air at > 65% relative humidity (RH) was found to be greatly enhanced by the > presence > of gaseous NO2. Exposures of 20–80 ppm SO2 + 10 ppm NO2 on 1 mg samples of > commercial carbon black were found to produce both sorption and desorption > coverages (weight retained after desorption into N2) of over one order of > magnitude greater than for corresponding SO2exposures. Significant > agglomeration and wetting were observed to occur progressively during > exposures at 65% RH and samples, even after 150 h exposure, rarely reached > steady-state weight gain. The wetting may have regenerated fresh reactive > carbon surface. Sorptions conducted in nitrogen atmospheres, rather than > in > air, appeared to produce slightly higher sorptions and weight retentions > for equivalent exposure concentrations and times, indicating that > NO2 served as the oxidizer and that molecular oxygen, or some trace > constituents in air, may have weakly inhibited the oxidation by NO2. Wet > chemical analysis of the desorbed phase indicated that sulfate, presumably > H2SO4, accounted for over half of the retained weight. Measurements of pH > from water-quenched samples indicated a highly acidic surface phase and > suggested the oxidation process could process in an acidic environment.".* > > > Also, in searching for the Solomon paper (and related issues) through this > forums' records, I found that the water vapor reduction (non-BC wetting > methods) issue has been touched upon by other list members. Please see the > below links. > > Utilising Cloud Cover Elevation Alteration to Control Global Warming > <https://groups.google.com/d/msg/geoengineering/M6WJt4HjccA/vVPWDcbTQ5YJ> > > Can we modify stratospheric water vapor by deliberate cloud seeding? Chen, > JGR Atmospheres, Wiley > <https://groups.google.com/d/msg/geoengineering/I7pfO-6b2o4/63WeU5eK96YJ> > > Further (highly interesting) BC related information can also be found in > the following links. > > Bounding the role of black carbon in the climate system: A scientific > assessment <http://escholarship.org/uc/item/1c68530v#page-1> > > Atmospheric Aerosols: Composition, Transformation, Climate and Health > Effects > <http://atmo.tamu.edu/courses/atmo689-gs/lectureweek10/aerosolreview.pdf> > > Atmospheric processes, tropospheric ozone and black carbon > concentrations, deposition and radiative forcing > <http://www.unep.org/dewa/Portals/67/pdf/03_BC_Chap3_Low_res.pdf> > > Best regards, > > Michael > > > > On Friday, August 1, 2014 5:53:56 AM UTC-7, Renaud de_Richter 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. 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