Yes, cloud modifications were extensively discussed. The main take-away for me was the limit to capacity of both cirrus stripping and MCB.
Andrew On 8 Jul 2015 13:39, "Stephen Salter" <[email protected]> wrote: > Hi All > > Was there never a mention of tropospheric marine cloud brightening? > > Stephen > > Emeritus Professor of Engineering Design. School of Engineering, > University of Edinburgh, Mayfield Road, Edinburgh EH9 3JL, Scotland > [email protected], Tel +44 (0)131 650 5704, Cell 07795 203 195, > WWW.homepages.ed.ac.uk/shs, YouTube Jamie Taylor Power for Change > On 08/07/2015 08:57, Andrew Lockley wrote: > > > http://www.spp-climate-engineering.de/symposium-blog-single/items/day-1-could-we.html > > Day 1 - Could we? > 07.07.2015 22:42 (comments: 0) > tl_files/ce-projekt/media/aktuelles/Day1_07.png > > Day 1: Tuesday July 7, 2015 - Berlin-Brandenburg Academy of Sciences and > Humanities > > Although many hold high hopes for the next international climate > conference in Paris this winter (COP 15), evidence suggests that > environmental, technological, economic and social inertia will prevent the > world's major polluters from reducing carbon dioxide emissions fast enough > to prevent dangerous climate change. This has led to the increased > consideration of a range of Climate Engineering (CE) technologies, which > can be grouped into two main categories; Carbon Dioxide Removal (CDR) > methods, which aim to reduce the levels of carbon dioxide (CO2) in the > atmosphere, allowing outgoing long-wave heat radiation to escape more > easily, and Solar Radiation Management (SRM) methods, which aim to reduce > the net incoming short-wave solar radiation and thus warmth reaching the > Earth. While SRM technologies may be able to reduce the risks associated > with rapid climate change, they do not represent an alternative to carbon > management. As Klaus Lackner outlined in today's introductory lecture, the > inherent inertia of the global carbon system means that stabilizing > emissions to meet the 2 degree target outlined by the IPCC requires not > only the reduction of global net emissions to zero, but also implies the > need for negative emissions. Therefore, as the symposium's opening > presentation emphasized, a deeper understanding of the feasibility of both > CDR and SRM technologies is needed as soon as possible. > This week's symposium aims to deal with a wide spectrum of Climate > Engineering related questions, but today's session focused on what is > arguably one of the most fundamental of them all: Could we do it? [1] > Entitled "Scientific Feasibility of Climate Engineering Ideas," the first > session of the week included talks by seven natural scientists and > engineers who addressed the "Could we?" question from different > perspectives. > We were updated on a plurality of practical CE puzzles being addressed > around the world. First, Jon Egill Kristjansson told us about the fine line > a potential cloud seeder would have to walk by seeding small, homogenous > ice nuclei in cirrus clouds, which then cool the planet by letting more > long-wave radiation out, but making sure not to "over-seed", as injecting > too many nuclei would mean reduced solar reflection and subsequently more > warming. We heard that although initial modeling on cirrus cloud "thinning" > in this manner indicates that the method is scientifically feasible, as one > member of the audience pointed out, very little is known about its > technical feasibility. The creation of small, homogenous ice nuclei in > cirrus clouds could cool the planet, but a multitude of questions remain > regarding how, where and under what conditions such particles can be > successfully created. > tl_files/ce-projekt/media/aktuelles/Day1_11.png > > The second speaker, Rolf Müller, filled us in on how little is currently > known about the way in which injecting sulphates into the stratosphere may > affect the ozone layer. He went on to emphasize that future models need to > look at the sensitivity of chlorine particles and moisture when assessing > the effects of sulphur-based Solar Radiation Management (SRM) techniques. > In a related talk on the technical complications associated with getting > sulphur particles up into the stratosphere some 20 km above our heads, Hugh > Hunt explained that delivering 10 million tonnes of particles a year using > aircraft would roughly double today's global aviation traffic, requiring > approximately 30,000 flights per day. A potentially much less expensive > (and considerably quieter) alternative involving only 10 tethered balloons > with hoses attached, delivering a steady flow of particles at a rate of 300 > kg per second would seem a much simpler option. But then we heard about the > troubles the wind poses for this type of delivery system, the fact that a > tether strong enough hold an enormous balloon 20 km above the Earth's > surface for an indefinite period does not yet exist, and the fear that CO2 > pumped up such a long hose would need to be under such high pressure that > it would solidify rather than "flow steadily" as originally envisioned. > Other open questions raised in the subsequent discussion included the > suitable framing of future tests; potential incompatibility between the > scientifically optimal location for the launch of such balloons and the > technical practicalities involved (weather conditions, population, flight > paths etc); and the concern that successful initial testing may lead to the > method becoming increasingly "politically tempting." > tl_files/ce-projekt/media/aktuelles/Day1_12.png > > Coming down from the heavens, Lena Boysen followed with her talk focused > on the potentials of terrestrial CO2 sequestration using biomass > plantations. Although these sequestration alternatives are often considered > attractive and "green," today we heard that they are likely to have a > multitude of side-effects on the water cycle, food production, biodiversity > and the planet's albedo. Additionally, modeling results suggest that even > dramatic shifts in land use would not remove enough carbon from the > atmosphere to reduce warming significantly: Even simulated so-called 100% > replacement scenarios in which all agricultural land was replaced with > biomass plantations did not result in a dramatic reduction in warming > within the model parameters. Greening the planet may be desirable for a > variety of reasons, but this presentation suggested afforestation alone > will not be enough to reduce warming significantly. > The final two presentations on this warm Tuesday in Berlin [2] focused on > olivine accelerated weathering, with Peter Köhler looking at ocean > fertilization and Thorben Amann discussing the effects of element release > as a consequence of land-based weathering. A simulated CO2 removal > experiment on the role of iron during olivine dissolution in the open ocean > showed that the size of the olivine grains played a huge role in the > effective dissolution: Too large and they sink, too light and they remain > in the surface layers. Questions were raised by members of the audience > about how the grains of the optimal size would be sourced - would naturally > ground small particles be transported from beaches, or would larger > particles be ground, and how would the energy use of the two options > compare? The land-based use of ground rock particles poses different > problems - during the final presentation of the day, Thorben Amann > indicated that although the particles can release fertilizing nutrients > which could be beneficial to agriculture, the rock types with most enhanced > weathering carbon capture potential also contain trace heavy metals. The > use of this method would therefore boil down to a trade-off between > fertilising potential, trace metal release level and CO2 capture potential. > After a long, interesting day of talks, we found ourselves trickling out > of the conference hall with even more questions to ponder. Today's speakers > showed us that before an answer to the deceptively simple query posed at > the start of this post can be found, a multitude of much more complex > questions remain to be answered > -- > 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 [email protected]. > To post to this group, send email to [email protected]. > 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 [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/geoengineering. > For more options, visit https://groups.google.com/d/optout. > > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > -- > 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 [email protected]. > To post to this group, send email to [email protected]. > 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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