[Phys-L] Re: global warming

[jsd at AV8N.COM (John Denker)]

David T. Marx wrote:

> My point on this is that how can we rely on climate models to
> determine global temperatures 50 to 100 years in the future, when we
> can't even predict temperatures next week or next month?

I assume that question was asked somewhat sarcastically,
as a rhetorical question.

Unlike most rhetorical questions, this one has a perfectly
plain sensible answer.

It is a truism, indeed a proverb in meteorology that:

   It is easier to predict what the weather will be for
   this month next year than for this day next week.

So let me ask each phys-l member:  Ask yourself, what
does this proverb tell us?  How can such a state of
affairs arise?

Robert Cohen already gave a hint about a big part of
the answer.

> I didn't make this up.  I read these numbers in a recent report from
> the American Meteorological Society.

Yeah, but taking numbers out of context so that their
meaning is totally changed is at least as bad as making
them up from scratch.

To say the same thing another way, the argument comes
down to saying, in effect:
   they can't predict everything, therefore
   they can't predict anything.
My point is that such an argument is a blatant violation
of the principles of logic.

=======================

1) From a distance, the whole "global warming" field looks
like a quagmire, with extremists on both sides making
outrageously illogical arguments.

But it is not wise to judge a field from such a distance.
By way of example, I did research in "neural networks" at
a time when 90% of the published papers were complete
hogwash.  At the same time, though, good work was being
done: real results with significant amounts of prompt and
lasting value.

It is important to recognize the difference.

2) Also it is important not to engage in "negative campaigning",
also known as "playing gotcha", by which I mean finding
the most outrageous statement made by the "other side" and
contradicting it, as if that settled the whole issue.

That's because even if the "other side" is wrong about one
thing, it doesn't mean they're wrong about everything.  If
a fool tells you that the sun will rise in the east tomorrow,
it might nevertheless be true.


Rick Tarara wrote in part:

> ...  so if we are to err, lets do so on the 'safe' side.

That is excellent advice, especially if/when the cost of being
on the safe side is small, and the consequences of being on
the other side are disastrous.

(At the other extreme, one can find proposed interventions
that are fantastically costly yet bring only infinitesimal
[or non-existent] increases in safety.  There springs to
mind the example of driving cross-country to avoid the
risk of airline crashes.  Or not vaccinating your kid, to
avoid the risk of an adverse reaction to the vaccine.)