[geo] Re: runaway climate changeNot 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
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Andrew C. Revkin
The New York Times / Environment
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