Great citation!  Love it.  Thank you so much, Chris.  Can you give us the
location in the document where you found the ranking stats?  I couldn't
find them.  (It's 6:30 in the morning here and before my morning coffee,
so perhaps I'm wandering aimlessly.  Without coffee, I tend not to look
very hard.)

I did find this set of claims, which is also relevant to abrupt climate
change:

:::::::::::::::::::::::::::::::::::::::::

http://www.grida.no/climate/ipcc_tar/wg2/679.htm

"19.6.1. The Irregular Face of Climate Change

Natura non facit saltus -- nature does not take jumps. Modern science has
thoroughly shattered this tenet of the Aristotelian school of thought.
Long-term observations and experimental insights have demonstrated
convincingly that smooth, or regular, behavior is an exception rather than
a rule. Available records of climate variability, for example, reveal
sudden fluctuations of key variables at all time scales. Large, abrupt
climate changes evident in Greenland ice-core records (known as
Dansgaard-Oeschger oscillationsDansgaard et al., 1993) and episodic,
massive discharges of icebergs into the North Atlantic (known as Heinrich
eventsBond et al., 1992) are obvious examples of irregular behavior as a
result of weak external forcing. Ecosystems also display discontinuous
responses to changing ambient conditions, such as changes in disturbance
regimes (Holling, 1992a; Peterson et al., 1998) and species extinctions
(Pounds et al., 1999). Irreversible changes in ecosystems are triggered by
disturbances (e.g., Gill, 1998), pests (e.g., Holling, 1992b), and shifts
in species distributions (Huntley et al., 1997). Irregular behavior is
accepted as a major aspect of the dynamics of complex systems (Berry,
1978; Schuster, 1988; Wiggins, 1996; Badii and Politi, 1997).

A quantitative entity behaves "irregularly" when its dynamics are
discontinuous, nondifferentiable, unbounded, wildly varying, or otherwise
ill-defined. Such behavior often is termed singular, particularly in
catastrophe theory (Saunders, 1982), and illustrates how smooth variations
of driving forces can cause abrupt and drastic system responses. The
occurrence, magnitude, and timing of singularities are relatively
difficult to predict, which is why they often are called "surprises" in
the literature.

It is important to emphasize that singular behavior is not restricted to
natural systems. There has been speculation, for example, about possible
destabilization of food markets, public health systems, and multilateral
political agreements on resource use, but solid evidence rarely has been
provided (e.g., Ds, 1994; Hsu, 1998). Rigorous scientific analysis of
certain classes of singular socioeconomic phenomena is emerging (Bunde and
Schellnhuber, 2000), but huge cognitive gaps remain in this field.

Singularities have large consequences for climate change vulnerability
assessments. Unfortunately, most of the vulnerability assessment
literature still is focusing on a smooth transition from what is assumed
to be an equilibrium climate toward another equilibrium climate (often
1xCO2 to 2xCO2). This means that most impact assessments still implicitly
assume that climate change basically is a "well-behaved" process. Until
recently, only a few authors have emphasized the importance of
discontinuous, irreversible, and extreme events to the climate problem
(e.g., Lempert et al., 1994; Nordhaus, 1994a; Schellnhuber, 1997);
concerns about the impacts of these events and their consequences for
society now are becoming much more common. Singularities could lead to
rapid, large, and unexpected impacts on local, regional, and global
scales. Anticipating and adapting to such events and their impacts would
be much more difficult than responding to smooth change, even if these
responses must be made in the face of uncertainty. Furthermore,
singularities considerably complicate the search for optimal emissions
reduction strategies that are based on, for example, benefit-cost analysis
or tolerable emissions strategies that are based on, as another example,
the precautionary principle.

http://www.grida.no/climate/ipcc_tar/wg2/679.htm






On Fri, 27 Feb 2004, Chris Hope wrote:

> At 16:31 26/02/2004 -0500, Ben wrote:
> >I want to pipe in here, because I think this is an important issue and
> >I've wondered why there's not better follow-up in the press.
> [snip]
> >
> >The question, however, is what the meaning of "likely" or "not the most
> >likely" is.  Does "likely" mean, "more than a 50% likelihood"?  If so,
> >which it seems like "likely" must mean, then it's a darn good thing that
> >such a scenario is not likely.  But I'm not sure that we should be so
> >reassured that it's only not "likely".  If, on the other hand, "not the
> >most likely" means that it is not the most likely among multiple
> >scenarios, then it would be really important for us to figure out how many
> >scenarios there are, and how likely those scenarios are, for then we would
> >have a better sense of what the estimation of likelihood would be.  10
> >possible scenarios, one with a likelihood of 51%, eight with a likelihood
> >of 1%, and one with a likelihood of 41% would still mean that it was 41%
> >likely that such abrupt climate change would occur.
> >
> >Obviously, all of this speculation is just speculation...but I guess
> >that's my point: this discussion here is really speculation, and nobody
> >seems to be clear about how likely such a scenario could be.
> >
>
> Ben's exactly right that the probabilities are important here. It's not
> quite true that no-one has done any work on this. If you look at the last
> IPCC report from 2001 you will see that an effort was made to quantify
> confidence levels and use them consistently, with 'very high confidence'
> being 95% or greater, 'high confidence' 67-95% and so on (Working Group II,
> technical summary, page 21).
>
> If we turn to the kind of climate change in the Pentagon report, it would
> come under the IPCC's heading of 'risks from future large scale
> discontinuities'. In one of the key figures from the IPCC report (figure
> SPM-2 on page 4 of the Working Group II summary for policymakers), these
> risks were given a very low  (under 5%) chance of occurring for global
> temerature changes of up to about 3 degC. The same figure shows that there
> are no scenarios which reach a 3 degC global temperature change before
> 2050; the majority reach this around 2080 or beyond.
>
> So, on this basis, a scenario that has 'major European cities ... sunk
> beneath rising seas as Britain is plunged into a 'Siberian' climate by
> 2020' is very much a worst case, lying well beyond the IPCC's ranges.
>
> All of this is not only in the public domain, but available for free from
> the IPCC's website (www.ipcc.ch). It makes a sensible starting place for
> anyone wanting to see what the scientific consensus is on climate change.
> Of course, it's quite possible to argue that the scientists have got it
> completely wrong, but it would be prudent to be able to say why you think
> they have got it wrong.
>
> Chris
>
>
> Chris Hope, Judge Institute of Management,
> University of Cambridge, Cambridge CB2 1AG, UK.
> Voice: +44 1223 338194.   Fax: +44 1223 339701
> e-mail: [log in to unmask]
>

Ben Hale
Philosophy Department
SUNY at Stony Brook
Stony Brook, NY 11794

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                  http://www.sinc.sunysb.edu/Stu/bhale
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"But you know, grandson, this world is fragile."

The word he chose to express "fragile" was filled with the intricacies of
a continuing process, and with a strength inherent in spider
webs. . . . It took a long time to explain the fragility and intricacy
because no word exists alone, and the reason for choosing each word had to
be explained with a story about why it must be said this certain way. That
was the responsibility that went with being human . . . and this demanded
great patience and love.

--Leslie Marmon Silko (Laguna Pueblo)