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_change for 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 about, but "climate change" is almost interchangeable >>>>> with >>>>> "global warming" these days. >>>>> >>>>> 2. The domino effect is mentioned here: >>>>> http://researchpages.net/ESMG/people/tim-lenton/tipping-points/ >>>>> >>>>> The release of methane is likely to be triggered by the loss of Arctic >>>>> sea >>>>> ice, according to David Lawrence: >>>>> http://www.ucar.edu/news/releases/2008/permafrost.jsp >>>>> >>>>> 3. I believe it is generally accepted that the Arctic sea ice albedo >>>>> effect >>>>> contributes to the accelerated warming trend in the Arctic region. It >>>>> is >>>>> also accepted that this effect presents a strong positive feedback on >>>>> the >>>>> local warming, but currently presents only a weak positive feedback on >>>>> global warming. Thus if the local warming can be halted, and methane >>>>> release domino effect thereby avoided, then we can avoid passing a >>>>> point >>>>> of >>>>> no return, or going "over the waterfall" as you put it. >>>>> >>>>> I'd be interested to know if Prof John Shepherd agrees with this >>>>> assessment. >>>>> >>>>> 4. Additional point - only albedo (shortwave radiation) geoengineering >>>>> has >>>>> any chance to halt the local warming in the Arctic. >>>>> >>>>> Again I'd be interested to know whether Prof Shepherd agrees with this. >>>>> >>>>> Cheers, >>>>> >>>>> John >>>>> >>>>> >>>>> ----- Original Message ----- >>>>> From: "Andrew Lockley" <[email protected]> >>>>> To: "geoengineering" <[email protected]> >>>>> Sent: Sunday, February 01, 2009 12:33 PM >>>>> Subject: [geo] runaway climate change >>>>> >>>>> >>>>> I'm working on http://en.wikipedia.org/wiki/Runaway_climate_change >>>>> >>>>> and there are a few crucial questions I could do with help on: >>>>> >>>>> 1) Is the term 'Runaway climate change' seen as kosher, or is it >>>>> purely a pop-science concept? >>>>> 2) How widespread is support for the idea of an ice-albedo followed by >>>>> a clathrate/permafrost domino effect? Is it speculative or accepted? >>>>> 3) Is there consensus on 2) above as regards timing? All the sound >>>>> evidence I've read says we've already fallen over the waterfall. Do >>>>> others agree? >>>>> >>>>> If you have any general thoughts on the matter, or notable people and >>>>> sources you'd care to inform me of, then please email back >>>>> [snip] >>>>> >>>>> >>>>> >>>> >>>> >> >> >> > > > > > > > -- > Best wishes, > > ------------------------------------------------------------------- > Dr. G. Bala > Associate Professor > Center for Atmospheric and Oceanic Sciences > Indian Institute of Science > Bangalore - 560 012 > India > > Tel: +91 80 2293 2698 > +91 80 2293 2505 x206 > +91 9741991621 (cell) > Fax: +91 80 2360 0865 > Email: [email protected] > [email protected] > Web:http://caos.iisc.ernet.in/faculty/gbala/gbala.html > ------------------------------------------------------------------- > > > > -- > > Andrew C. Revkin > The New York Times / Environment > 620 Eighth Ave., NY, NY 10018 > Tel: 212-556-7326 Mob: 914-441-5556 > Fax: 509-357-0965 > http://www.nytimes.com/revkin > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
