Re: [asa] The Mathematics of Global Warming

From: Schwarzwald <schwarzwald@gmail.com>
Date: Mon Nov 30 2009 - 18:45:56 EST

Heya all,

I've read some people expressing exasperation at the idea that climate
scientists could be exaggerating their findings about climate change, the
certainty of their predictions of what this will mean in the future, etc. I
think the attitude can be summed up by the following.

*Why in the world would anyone hope that the planet was in danger? If there
wasn't a major threat of cataclysmic disaster owing to humanity's actions,
we would be ecstatic! It would be a tremendous weight off our shoulders, and
the shoulders of all the scientists involved! Obviously we don't *want*
these such things to come to pass. So why in the world would anyone ever
mislead about such things?

*The problem with this question is I can turn around and ask the same of the
climate skeptics: Why in the world would they say what they do if they did
not truly believe the science was illegitimate? Presumably "Big Oil" and
other CO2 producers are run by people who, in fact, live on this planet -
and thus themselves, their children, and their grandchildren will experience
the effects of these coming disasters if they're real. Why would they
deceive anyone?
*
*To answer that question for the skeptics is to answer it for the
'consensus'. Accusations of businesses standing to gain or lose, of
political interests directly and indirectly related to climate change
politics, of the personal reputations and pride of particular scientists or
visible leaders, etc can flow both ways. It's not as if abusing science for
political or social ends is some new and strange practice.
*
*Of course, the fact that motivations could conceivably be playing a role
does not mean the science itself is debunked, or even incorrect. But the
"Why in the world would anyone lie about or exaggerate their findings?"
question is, in my view, very naive. Why in the world would a researcher
fake some of his research (Hwang Woo-Suk)? Why would the PETA exaggerate the
health risks of eating meat, or downplay the health risks of a vegan
lifestyle? What possible motivation could anyone have for exaggerating or
downplaying climate trends and risks, when the only thing at stake are
social/political policies, prestige, and more?

2009/11/30 Cameron Wybrow <wybrowc@sympatico.ca>

> Iain:
>
> I believe that the "wishful thinking" referred to in the article is
> "wishful thinking" about the adequacy of current mathematical models to
> handle complex and not-fully-understood climate systems, not a "wish" that
> the world should be subjected to catastrophic global warming.
>
> Cameron.
>
>
>
> ----- Original Message -----
> *From:* Iain Strachan <igd.strachan@gmail.com>
> *To:* John Walley <john_walley@yahoo.com>
> *Cc:* AmericanScientificAffiliation <asa@calvin.edu>
> *Sent:* Monday, November 30, 2009 8:14 AM
> *Subject:* Re: [asa] The Mathematics of Global Warming
>
> OK I'm not an expert in the mathematical models used for climate modelling,
> but I am familiar with the problems related to solving non-linear
> differential equations - a non-linear equation of order as low as three can
> exhibit chaotic behaviour - which means that the solutions diverge with time
> due to arbitrarily small changes in initial conditions.
>
> I think this is the substantive point that is being made, and it is correct
> in as far as it goes, were it not for the fact that other techniques can be
> applied to counter this problem. For example a related problem is the
> modelling of turbulent fluid flow in Computational Fluid Dynamics (CFD)
> which arises as a result of the Navier-Stokes equations. Again, I am not an
> expert in this, but my drinking partner is a world expert on this and author
> of some of the largest software packages in this field. This excerpt from
> Wikipedia (on Navier-Stokes equations) gives some idea of the type of
> techniques employed:
>
> ----
> The numerical solution of the Navier-Stokes equations for turbulent flow is
> extremely difficult, and due to the significantly different mixing-length
> scales that are involved in turbulent flow, the stable solution of this
> requires such a fine mesh resolution that the computational time becomes
> significantly infeasible for calculation (see Direct numerical simulation<http://en.wikipedia.org/wiki/Direct_numerical_simulation>).
> Attempts to solve turbulent flow using a laminar solver typically result in
> a time-unsteady solution, which fails to converge appropriately. To counter
> this, time-averaged equations such as the Reynolds-averaged Navier-Stokes
> equations<http://en.wikipedia.org/wiki/Reynolds-averaged_Navier-Stokes_equations> (RANS),
> supplemented with turbulence models (such as the k- model), are used in
> practical computational fluid dynamics<http://en.wikipedia.org/wiki/Computational_fluid_dynamics>(CFD)
> applications when modeling turbulent flows. Another technique for solving
> numerically the Navier-Stokes equation is the Large-eddy simulation (LES).
> This approach is computationally more expensive than the RANS method (in
> time and computer memory), but produces better results since the larger
> turbulent scales are explicitly resolved.
> ----
>
> As far as I'm aware, this kind of technique is very successful and my
> friend's code was famously involved in reconstructing the events following a
> famous UK railway station disaster where a front of flame shot up an
> escalator shaft (Kings Cross disaster). The results from the code were
> verified using a scale model.
>
> Hence I don't think it's as simple as saying that if there are non-linear
> equations then you can't have any idea of the solution.
>
> I would also add that the writer refers to "wishful thinking" as a basis
> for economic policy.
>
> Would it not be more accurate to say that those who insist that climate
> change is NOT going to happen are indulging in wishful thinking?
>
> I for one have no great desire to see global warming come true. I would
> love it if the whole thing was found to be a complete hoax, and to wake up
> one morning and find out it wasn't true, and that my grandchildren weren't
> going to inherit a world ravaged by flood, famine, disease and war. To
> suggest that those who believe this will happen are indulging in "wishful
> thinking" is absolutely preposterous.
>
> Iain
>
>

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Received on Mon Nov 30 18:46:16 2009

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