Dear Andrew, We need to read the explanation of Runaway Greenhouse Efffect in Wayne 1st ed pg. 49. I will dictate into an email soon.
Sincerley, Oliver Wingenter On Feb 2, 4:50 pm, Andrew Lockley <[email protected]> wrote: > I have an alternative theory as to why we don't see too many instances > of runaway climate change from the 'clathrate gun' effect, or from > permafrost. > > Methane has a very short life in the atmosphere, but is a potent > greenhouse gas. If the rate of warming is low, a little methane is > released, which quickly degrades to CO2 which has little short term > effect and can then disappear into sinks. As warming continues, more > methane is released, but never fast enough to make a significant > difference to the climate before it degrades again to CO2. > > HOWEVER: > > In AGW, the temperature is rising very fast. This has the potential > to make methane belch out from soils and seas very quickly. This > speed is of the essence, as large quantities of methane will be enough > to influence future methane release to create a runaway event. > > The process is like pull starting a chainsaw. A little tug gets you > the odd cough. Tug hard, the the chainsaw motor gets started and runs > on its own. > > Now, pretty please with sugar on top, can someone tell me what the > proper, scientific, not-to-be-argued with name for that process is? > The people on wikipedia really don't like 'runaway climate change' - > as apparently 'proper' climate scientists don't use that term. > Citations much appreciated, thankyou!! > > A > > 2009/2/2 Alvia Gaskill <[email protected]>: > > > Not enough CO2 in the atmosphere. > > > ----- Original Message ----- > > From: Andrew Revkin > > To: [email protected] ; [email protected] > > Cc: [email protected] ; Tom Wigley ; Andrew Lockley ; geoengineering ; > > Prof John Shepherd ; Tim Lenton ; David Lawrence > > Sent: Monday, February 02, 2009 3:29 PM > > Subject: [geo] runaway climate change > > Who on this list knows why the Arctic warming ~ 8,000 years ago (quite > > protracted and significantly warmer than today) did not lead to "runaway" > > warming? > > Presumably something kicked in the other direction? > > I'm pursuing a clearer picture of lessons from the Holocene and the Eemian > > (the previous interglacial) related to feedbacks and whether there are, or > > are not, one-way doors in the climate system. Leads eagerly pursued. .. > > Andy > > At 5:29 PM +0530 2/2/09, Govindasamy bala wrote: > > > Runaway feedback means running its course completely. It is feedback > > specific. > > > A good example is the presumed water vapor feedback on Venus. > > Apparently, earth and venus started with similar amount of h2o. > > Because Venus started with much higher surface temperature, the evolution of > > temperature and water vapor never intercepted the phase line of vapor and > > liquid. The climate warmed until all the water got evaporated. Basically, > > there was no sink for vapor which precipitation. On earth, this is not going > > to happen because we got the precipitation sink on earth...how lucky we are. > > > But I guess we do have runaway ice-albedo feedback on earth. we could get > > ice-free planet or snowball earth........ > > > Cheers. > > Bala > > > On Mon, Feb 2, 2009 at 5:03 PM, Eugene I. Gordon <[email protected]> > > wrote: > > > I guess it is not going to end. > > > A runaway train meets only #2 and even that has to be qualified because the > > train eventually runs out of (fossil?) fuel or track. Certainly climate has > > run away a half dozen times in 540 million years but always hits a limit > > which seems to be 24C except when an asteroid hits. It eventually turns > > around after remaining at the limit temperature for many millions of years. > > We have been in a runaway mode for the last 18,000 years but with some > > superimposed small wiggles in temperature. Without geoengineering the > > temperature will certainly get to the 24 C limit. > > > I think runaway is appropriate for the current situation even if there may > > be better suited terms. > > > -----Original Message----- > > From: [email protected] > > > [mailto:[email protected]] On Behalf Of John Nissen > > Sent: Monday, February 02, 2009 6:08 AM > > To: Tom Wigley; Andrew Lockley > > Cc: geoengineering; Prof John Shepherd; Tim Lenton; David Lawrence > > Subject: [geo] Re: runaway climate change > > > Dear Tom, > > > The concept of "runaway" has certain connotations: > > > 1. Significant in resultant effect > > 2. Uncontrollable > > 3. Exponential initial behaviour - characteristised by acceleration of > > process 4. No obvious limit 5. Irreversible 6. Rapid. > > > These can all be applied to climate change: > > > 1. "Significant" could be over 5 degrees global warming, sufficient for a > > mass extinction event. Or it could be applied to several metres of sea > > level rise. > > 2. "Uncontrollable" could be where anthropogenic greenhouse gas emissions > > reduction would not have a significant effect on the rate of climate change. > > 3. Exponential behaviour could be caused by a "tipping" of some part of the > > climate system, such as Arctic sea ice or methane release, where there is > > strong positive feedback. > > 4. There would be no obvious final equilibrium temperature - mainly because > > of the difficulty of modelling positive feedback and its behaviour over > > time. > > 5. It would be extremely difficult or impossible to reverse processes such > > as methane release or Greenland ice sheet disintegration, although it is > > conceivable to halt these processes or even reverse their effects > > (presumably through geoengineering). > > 6. "Rapid" could be anything from one season to 3000 years, on a geological > > timescale. > > > Therefore I think that "runaway" captures the semantics that we require for > > > the climate change that would result from, for example, a massive methane > > release, triggered by Arctic sea ice disappearance. Can you think of a > > better word to capture the six characteristics above, especially as > > applicable to climate change? > > > Cheers, > > > John > > > ----- Original Message ----- > > From: "Tom Wigley" <[email protected]> > > To: "Andrew Lockley" <[email protected]> > > Cc: <[email protected]>; "geoengineering" > > <[email protected]>; "Prof John Shepherd" > > <[email protected]>; "Tim Lenton" <[email protected]>; "David Lawrence" > > <[email protected]> > > Sent: Monday, February 02, 2009 3:43 AM > > Subject: Re: [geo] Re: runaway climate change > > >> Andrew, > > >> Poor analogy. running does not equal running away. > > >> More importantly, just because a term has been misused in the > >> past does not mean we should perpetuate its misuse (or use). > >> If the word is to be used at all (and, as a practicing scientist, > >> I never have or will), one should start off by saying that the > >> word runaway is open to misinterpretation, that it does not > >> mean running off to infinity, and that it's real meaning is ... > >> etc. etc. Then talk about irreversible changes (with the caveat > >> that even these are probably not irreversible), positive > >> feedbacks (which also have limits), etc. > > >> Tom. > > >> +++++++++++++++++++++++==== > > >> Andrew Lockley wrote: > >>> For better or worse, the term is now in general use in scientific, > >>> industrial, environmental and general media. (See > >>>http://en.wikipedia.org/wiki/Runaway_climate_changefor refs.) > > >>> I don't agree with Tom about 'to infinity and beyond'. I run as a > >>> hobby, and I've never run to infinity (or beyond). I think most > >>> people realise that runaway doesn't mean run-for-ever. > > >>> However, a general definition would be very useful. > > >>> A > > >>> 2009/2/2 <[email protected]>: > >>>> Dear All, > > >>>> I've said this before, but here goes again. > > >>>> If one sticks to dictionary definitions of words (which I > >>>> think is wise) then there is no such thing as "runaway" > >>>> climate change. Strictly, using the words of Buzz Lightyear, > >>>> "runaway" must mean "to infinity and beyond". > > >>>> Further, the word "runaway" is loaded and should be eschewed > >>>> in the climate context. > > >>>> The confusion here is that what some people are calling > >>>> "runaway" climate change is really better referred to as > >>>> "irreversible" climate change. For instance, the sudden release > >>>> of a large amount of CH4 would possibly cause large warming > >>>> that would put the globe in a new state that was much warmer > >>>> than present. But the climate (or global-mean temperature) would > >>>> *not* runaway -- it would eventually stabilize. Even this change > >>>> would not strictly be irreversible, as the excess CH4 would > >>>> slowly be oxidized (more slowly than today because of the well > >>>> known positive feedback of CH4 on its own lifetime due to OH loss), > >>>> but a lot of the excess CH4 would slowly disappear and be replaced > >>>> by CO2 that has less forcing. This CO2 would, of course, stay > >>>> around for a long time. > > >>>> If anyone is interested, this case can easily be run with MAGICC, > >>>> but some minor tweaks are needed to get the CH4 to CO2 flux right. > >>>> Conceptually trivial. > > >>>> So, please, please try not to cry wolf with these loaded and sadly > >>>> oft-misused words. > > >>>> Tom. > > >>>> ++++++++++++++++++++++++++++ > > >>>>> Andrew, > > >>>>> 1. I think the concept of runaway climate change is kosher. See this > >>>>> quote > >>>>> from > >>>>>http://www.meridian.org.uk/_PDFs/FeedbackDynamics.pdf > > >>>>> "The possibility of a tipping point in the earth system as a whole > >>>>> which > >>>>> prevents the recovery of stable equilibrium and leads to a process of > >>>>> runaway climate change, is now the critical research agenday, requiring > > >>>>> the > >>>>> concerntration of global resources in a "Manhattan Project" style > >>>>> engagement. All other work on impact assessment, mitigation and > >>>>> adaptration > >>>>> depends on the outcome of thie overarching issue" > > >>>>> I would prefer to have "runaway global warming", because that's what we > >>>>> are > >>>>> really talking > > ... > > read more » --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
