This discussion is not really useful anymore. Runaway means uncontrolled and nothing more. It does not mean to infinity or too fast, it simply means we have not regained control. Techniques are in use for controlling trains out of control but until they are used the train is in a runaway condition. Why do we not accept that the term is in use and get on to more useful topics?
-----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tom Wigley Sent: Sunday, February 01, 2009 10:43 PM To: Andrew Lockley Cc: [email protected]; geoengineering; Prof John Shepherd; Tim Lenton; David Lawrence Subject: [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] >>> >>> >>> >>> >> --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
