For very large perturbations it is a tedious and complex calculation,
but for relatively small perturbations a linear approximation
suffices. It is true that the correction for large perturbations
reduces the contribution to slower than linear. The definition of
"large" depends on the particular constituent and the particular
atmosphere.
I think the 'global warming potentials" are some sort of
linearization, but the chemical lifetimes of the constituents are
taken into account in some way I don't understand. As a consequence I
am not sure that even with James' correction that Nils' calculation is
the right one, though something like it should be doable.
mt
On 8/16/07, [EMAIL PROTECTED] <[EMAIL PROTECTED]> wrote:
>
> > CO2-eq is used to mean the equivalent CO2 concentration, holding other
> > gases fixed at the pre-industrial level. So you have to subtract off the
> > pre-ind level off CH4 and N2O from your sums. I think what you have
> > effectively done is work out the CO2-equivalent if all other gases were
> > zero.
>
> So far so good, but:
>
> Can we really just add up like that? I understand that for CO2
> concentration the effect is logarithmic, presumably that's also the
> case for other GHG's and then isn't there such a thing as overlap
> between the absorption bands of different GHG's?
>
> I don't really understand the basic physics of spectroscopy very well,
> but from what I've read I thought it was a lot more complicated than
> simple addition?
>
>
> >
>
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