Very informative, thanks. I understand that OH radicals may be under significant pressure in the atmosphere, and that their loss may have significant consequences. I've not seen the consumption of OH raised as an issue here before. Is it important, or not? I have no idea how much OH there is, and how much might be used up by geoengineering. Could more be made if we needed it?
A 2009/9/19 <[email protected]>: > Well it is not quite so easy. > > Volcanic SO2 is so efficient at cooling the earth because it reaches a layer > in the stratosphere with primarily horizontal winds that spread it > efficiently around the globe. The elevation of that layer is set by the > thermal and chemical structure of the stratosphere. If anthropogenic SO2 was > not delivered to that specific layer, it would not be spread efficiently > around the earth and thus would not have the same cooling effect. > > Yes it does take 3 times as much water as SO2 to create the sulfuric acid > aerosol. Pinatubo ejected 15 to 19 Mt of SO2, thus if we mix 3 times as much > water,we must eject approximately 75 to 95 Mt of material, a significant > effort. We do not know how much of the volcanic SO2 was needed to form the > aerosol, but there are good estimates from satellites for the volume of > aerosol produced and my recollection is that a significant amount of SO2 > somehow made it to this thermal layer. I am traveling right now and not in a > position to look up the details. > > The well observed destruction of ozone by the Pinatubo eruption may have > been caused by several mechanisms. To form the aerosol, you need large > amounts of OH. OH is formed by the effects of ultraviolet sunlight on ozone > which in turn is formed by the effects of ultraviolet light on oxygen. The > rate of formation of the aerosol is controlled by the rate that OH is > produced. Thus it is possible that the sheer demand for OH caused a decrease > in ozone but this has not been proven. There is also a strong suggestion > that heterogenous processes on the surface of the aerosol instigated by HCL > and even H2SO4 and various gases produced by man caused destruction of ozone > and enlargement of the ozone hole. Thus the very presence of the aerosol > enhances ozone destruction. > > Adding anthropogenic SO2 to the stratosphere is not as simple as it seems. > We do not understand in detail the atmospheric chemistry that is likely to > ensue. Man has a poor record in trying to modify nature. We need to proceed > with caution. > Peter > > Hi All, > > During the second day of the Hazards Colloquium, during the evening dinner > venue , I had opportunity to discuss with Peter L. Ward about the > much-talked-about geoengineering idea of using stratospheric sulphur > dioxide to bring down the athmospheric temperatures. > > According to Peter the cooling effect of sulphur dioxide in isolation from > water in high stratosphere does not work very well because of the > stratospheric dry surroundings. Instead of sulphur dioxide, it would have to > be sulphuric acid that is shipped up into high athomosphere. > > The volume of water will have to be 3 times the amount of sulphur dioxide, > thus better results would come from using sulphuric acid readily. > > Peter also reminded that the sulphuric acid from Mt. Pinatubo destroyed > about 5% of the stratospheric ozone. It is, therefore, questionnable for > its large side effects, especially the attack of sulphur on ozone. > > To reduce the destruction of ozone layer, may be the spreading of sulphuric > acid should take place just below it to keep it just beneath the main ozone > belt but still a slightly higher than the clouds to prevent it flushed down > too soon. Any comments and opinon on this "opportunity window" just beneath > the ozone layer with a reduced impact to the ozone layer whilst still > cooling the skies somewhat long? > > Hope, I have cited Peter's dinner time comments above accurately - I didn't > drink too much wine, should be more or less put down correctly. > > Kind regards, > > Albert (the occasional heretic) > > >> > by Bill McGuire, at UCL, London. > > > >> Date: Fri, 18 Sep 2009 02:02:08 +0100 >> Subject: [geo] Re: Colloquium report: hazards from global warming >> From: [email protected] >> To: [email protected] >> CC: [email protected]; [email protected] >> >> >> This raises interesting points about the limits of SRM geoengineering. >> Perhaps the experts on the list could explain why frequent volcanic >> eruptions cause a warming effect? Can we be sure that H2S >> geoengineering techniques we propose cannot result in this 'blowback'? >> >> A >> >> 2009/9/17 John Nissen <[email protected]>: >> > >> > This is a press report on the first day of the Hazards Colloquium, >> > organised >> > by Bill McGuire, at UCL, London. >> > >> > http://planetark.org/wen/54708 >> > >> > Global Warming May Bring Tsunami And Quakes: Scientists >> > >> > Date: 17-Sep-09 >> > Country: UK >> > Author: Richard Meares >> > >> > LONDON - Quakes, volcanic eruptions, giant landslides and tsunamis may >> > become more frequent as global warming changes the earth's crust, >> > scientists >> > said on Wednesday. >> > >> > Climate-linked geological changes may also trigger "methane burps," the >> > release of a potent greenhouse gas, currently stored in solid form under >> > melting permafrost and the seabed, in quantities greater than all the >> > carbon >> > dioxide (CO2) in our air today. >> > >> > "Climate change doesn't just affect the atmosphere and the oceans but >> > the >> > earth's crust as well. The whole earth is an interactive system," >> > Professor >> > Bill McGuire of University College London told Reuters, at the first >> > major >> > conference of scientists researching the changing climate's effects on >> > geological hazards. >> > >> > "In the political community people are almost completely unaware of any >> > geological aspects to climate change." >> > >> > The vulcanologists, seismologists, glaciologists, climatologists and >> > landslide experts at the meeting have looked to the past to try to >> > predict >> > future changes, particularly to climate upheaval at the end of the last >> > ice >> > age, some 12,000 years ago. >> > >> > "When the ice is lost, the earth's crust bounces back up again and that >> > triggers earthquakes, which trigger submarine landslides, which cause >> > tsunamis," said McGuire, who organized the three-day conference. >> > >> > David Pyle of Oxford University said small changes in the mass of the >> > earth's surface seems to affect volcanic activity in general, not just >> > in >> > places where ice receded after a cold spell. Weather patterns also seem >> > to >> > affect volcanic activity - not just the other way round, he told the >> > conference. >> > >> > LONDON'S ASIAN SUNSET >> > >> > Behind him was a slide of a dazzlingly bright orange painting, "London >> > sunset after Krakatau, 1883" - referring to a huge Asian volcanic >> > eruption >> > whose effects were seen and felt around the world. >> > >> > Volcanoes can spew vast amounts of ash, sulphur, carbon dioxide and >> > water >> > into the upper atmosphere, reflecting sunlight and sometimes cooling the >> > earth for a couple of years. But too many eruptions, too close together, >> > may >> > have the opposite effect and quicken global warming, said U.S. >> > vulcanologist >> > Peter Ward. >> > >> > "Prior to man, the most abrupt climate change was initiated by >> > volcanoes, >> > but now man has taken over. Understanding why and how volcanoes did it >> > will >> > help man figure out what to do," he said. >> > >> > Speakers were careful to point out that many findings still amounted >> > only to >> > hypotheses, but said evidence appeared to be mounting that the world >> > could >> > be in for shocks on a vast scale. >> > >> > Tony Song of NASA's Jet Propulsion Laboratory in California warned of >> > the >> > vast power of recently discovered "glacial earthquakes" -- in which >> > glacial >> > ice mass crashes downwards like an enormous landslide. >> > >> > In the West Antarctic, ice piled more than one mile above sea level is >> > being >> > undermined in places by water seeping in underneath. >> > >> > "Our experiments show that glacial earthquakes can generate far more >> > powerful tsunamis than undersea earthquakes with similar magnitude," >> > said >> > Song. >> > >> > "Several high-latitude regions, such as Chile, New Zealand and Canadian >> > Newfoundland are particularly at risk." >> > >> > He said ice sheets appeared to be disintegrating much more rapidly than >> > thought and said glacial earthquake tsunamis were "low-probability but >> > high-risk." >> > >> > McGuire said the possible geological hazards were alarming enough, but >> > just >> > one small part of a scary picture if man-made CO2 emissions were not >> > stabilized within around the next five years. >> > >> > "Added to all the rest of the mayhem and chaos, these things would just >> > be >> > the icing on the cake," he said. "Things would be so bad that the odd >> > tsunami or eruption won't make much difference." >> > >> > > >> > >> >> >> > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en -~----------~----~----~----~------~----~------~--~---
