Hi Mike, Could there be a method of selective filtering of coal-fired power stations, such that the cooling aerosol (or SO2 precursor) is allowed into the troposphere while the black carbon is removed?
Cheers, John --- On Tue, Sep 11, 2012 at 7:15 PM, Mike MacCracken <mmacc...@comcast.net>wrote: > Hi Stephen—I would think that Chinese sulfate (like tropospheric sulfate > from virtually anywhere) would contribute to cloud and free air > brightening, so a cooling influence (especially when that sulfate is above > the dark Pacific Ocean). Now, in that coal plants put out more than pure > SO2, there might well be some components (such as black carbon) that would > exert a strong warming influence, especially if they are carried far enough > to deposit on snow and/or ice during the sunny half of the year in the > Arctic. For net effect, there is need for much more analysis than I have > seen. > > On limiting heat reaching the Arctic Ocean, there have been suggestions to > even build a dam across the Bering Strait—as long ago as the mid-20th > century (though I think then it was with the intent to warm the Arctic). My > guess on the kelp idea is that the sunny part of the year is not long > enough for that approach to be all that practical (not only is the sunny > part of the year short, but the sun angle is often not helpful). And sea > ice is typically only a few meters thickness, so no where near 30 m. > > Mike > > > > On 9/11/12 12:48 PM, "Stephen Salter" <s.sal...@ed.ac.uk> wrote: > > > Mike > > Do you think that the higher levels of SO2 from Chinese coal burning > could account for some of the increase in Arctic temperatures? > > Another thought for your list might be to increase the drag of water > flowing in through the Bering Strait. In summer kelp grows at an amazing > rate but not below about 30 metre water depth because of the shortage of > light. The net flow is 800,000 m3 a second and it will be warmer than > polar water so a small velocity reduction makes a big difference. What if > we put strong ropes moored at 30 metres to give them kelp a foot hold? If > kelp gets scraped off by floating ice it will can grow again. Does ice > reach down to 30 metres? > > Stephen > > On 11/09/2012 18:05, Mike MacCracken wrote: > > > > Re: [geo] Coupled Model Intercomparison Project 5 (CMIP5) simulations of > climate following volcanic eruptions In my view, this is just why > geoengineering efforts to cool the Arctic should consider as approaches: > (a) spring-summer only injection of the appropriate sulfur compound > (whatever will lead to sulfates) into the LOWER stratosphere or free > troposphere, (b) cloud brightening in region or over currents carrying heat > into the region, (c) approaches to brighten the surface albedo (e.g., > microbubbles) in or near the region, and, perhaps, (d) approaches to reduce > cirrus that are reducing IR loss. > > > Parallel to these efforts, we should also be working to limit emissions > of substances that amplify Arctic warming above and beyond the > amplification that happens due to natural processes, so black carbon from > sources in and near the region, etc. > > Mike > > > > > On 9/11/12 5:03 AM, "Stephen Salter" <s.sal...@ed.ac.uk> wrote: > > > > > Hi All > > Six out of the eight models in the Driscoll et al paper show near > surface-warming in Arctic winters following volcanic eruptions. This is in > line with figure 2a the Jones Hayward Boucher Robock 2010 paper in > Atmospheric Chemistry and Physics. The obvious mechanisms are blanketing of > outgoing radiation and side-scatter of high solar rays that might have > missed the polar regions. Given the concerns about the loss of Arctic ice > and increased methane release we will have to be very careful not to let > any geo-engineering sulphur that we inject at low latitudes reach the > Arctic in winter. > > Stephen > > On 10/09/2012 16:52, Simon Driscoll wrote: > > > > > > > Dear all, > > the published version (no longer PiP) is now available here: > > http://www.agu.org/pubs/crossref/2012/2012JD017607.shtml > > Warm regards, > > Simon > > > > > > ________________________________________________ > > Simon Driscoll > Atmospheric, Oceanic and Planetary Physics > Department of Physics > University of Oxford > > Office: 01865 272930 > Mobile: 07935314940 > > http://www2.physics.ox.ac.uk/contacts/people/driscoll > > http://www.geoengineering.ox.ac.uk/people/who-are-we/simon-driscoll/ > > > > > > > ------------------------------ > > *From:* geoengineering@googlegroups.com [geoengineering@googlegroups.com] > on behalf of Andrew Lockley [andrew.lock...@gmail.com] > *Sent:* 14 August 2012 02:06 > *To:* geoengineering > *Subject:* [geo] Coupled Model Intercomparison Project 5 (CMIP5) > simulations of climate following volcanic eruptions > > > > > > http://www.agu.org/pubs/crossref/pip/2012JD017607.shtml > > > The ability of the climate models submitted to the Coupled Model > Intercomparison Project 5 (CMIP5) database to simulate the Northern > Hemisphere winter climate following a large tropical volcanic eruption is > assessed. When sulfate aerosols are produced by volcanic injections into > the tropical stratosphere and spread by the stratospheric circulation, it > not only causes globally averaged tropospheric cooling but also a localized > heating in the lower stratosphere, which can cause major dynamical > feedbacks. Observations show a lower stratospheric and surface response > during the following one or two Northern Hemisphere (NH) winters, that > resembles the positive phase of the North Atlantic Oscillation (NAO). > Simulations from 13 CMIP5 models that represent tropical eruptions in the > 19th and 20th century are examined, focusing on the large-scale regional > impacts associated with the large-scale circulation during the NH winter > season. The models generally fail to capture the NH dynamical response > following eruptions. They do not sufficiently simulate the observed > post-volcanic strengthened NH polar vortex, positive NAO, or NH Eurasian > warming pattern, and they tend to overestimate the cooling in the tropical > troposphere. The findings are confirmed by a superposed epoch analysis of > the NAO index for each model. The study confirms previous similar > evaluations and raises concern for the ability of current climate models to > simulate the response of a major mode of global circulation variability to > external forcings. This is also of concern for the accuracy of > geoengineering modeling studies that assess the atmospheric response to > stratosphere-injected particles.Received 13 February 2012; accepted 24 July > 2012. > -- > You received this message because you are subscribed to the Google > Groups "geoengineering" group. > To post to this group, send email to geoengineering@googlegroups.com. > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > > > > > -- > You received this message because you are subscribed to the Google > Groups "geoengineering" group. > To post to this group, send email to geoengineering@googlegroups.com. > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > > > > > > > > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to geoengineering@googlegroups.com. > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > > > > > > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to geoengineering@googlegroups.com. > To unsubscribe from this group, send email to > geoengineering+unsubscr...@googlegroups.com. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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