[Phys-L] Re: global warming

[jsd at AV8N.COM (John Denker)]

David T. Marx wrote:
> Do you find data like that shown at
> http://www.koshland-science-museum.org/exhibitgcc/historical05.jsp
> convincing?

Well, let's think about that.  Suppose I roll a die, once,
and it comes up "4".  Do I take that as evidence that the
die is loaded?  No.  Do I take that as evidence that the
die is not loaded?  No.

OTOH suppose I perform thousands of rolls, and they are,
as a whole, overwhelmingly biassed toward higher than
average numbers.  That starts to look like evidence.

So ... It comes down to what you mean by "data like that".
If you take _all_ the available data like that, it adds up
to something pretty scary.

The evidence for what's causing the warming is not as
overwhelming than the evidence for the warming itself.
It is also not entirely relevant.

If I move from the US to France, I'm not going to take
a US-style TV with me.  I don't necessarily care who's
to 'blame' for the 50Hz, 220V, SECAM situation;  my
actions are dictated by the simple observable facts.

> Finally, how can one compare local temperature variations with that
> which is happening for the whole Earth?

It is not necessary to "compare" local to global.  One
can _derive_ a worldwide number from a suitable collection
of local numbers in the obvious way.

> I might point out that meteroligists attempt to predict the weather
> for the next five to seven days using such models.  They are right
> about 20-25% of the time.

That seems short on common sense and long on axe-grinding.

If the task is to predict whether next week will be
warmer or cooler than this week, I can get it right
50% of the time by tossing a coin.  If Prof. Marx's
assertion is true, then I can get it right 75-80%
of the time by taking the "meteoroligists" prediction
and predicting the opposite.