On Jan 15, 9:25 pm, James Annan <[email protected]> wrote:
> DrNickBone wrote:
> > James,
>
> >> Um....if you really need a citation, some are mentioned in
>
> >>http://www.clim-past.net/5/803/2009/cp-5-803-2009.html
>
> > Thanks for this. This part of your paper jumped out at me:
>
> >> For the doubled CO2 experiment a number of the ensemble
> >> members with higher control temperature and high sensitivity
> >> became unstable once the global mean surface temperature
> >> exceeded 296 K.
>
> > That 296K seems close to the ~300K mentioned above by hgerhauser
> > (post of 7th January).
>
> Yes, I'd noticed the interesting coincidence. However, it may just be a
> model quirk. Once the atmosphere is that much warmer, the structure has
> may have changed sufficiently that the assumptions that went into the
> model may not be valid. Specifically, whe discussing this with others, I
> have heard people suggest that the ozone in the upper atmosphere may end
> up misplaced relative to the (new) atmospheric structure. But I don't
> know anything about this. Maybe I should look into it since we have
> several runaway models.
>
> Google finds this, don't think anyone has mentioned it.
>
> http://ams.allenpress.com/perlserv/?request=get-document&doi=10.1175%...
>
> James
That link is interesting. I think they are saying when the solar
constant, currently equal to 1450 Wm-2 reaches 1600 Wm-2 in
1,000,000,000 years time then bye bye. However, in the abstract they
state:
"The calculated values of the upper limit of radiation and water vapor
content cannot be
directly applied to describing real planetary atmospheres, since the
model physical processes are quite simple—
gray radiation scheme without clouds."
But we know that the atmosphere is not gray. It is banded. Moreover,
my idea that the clouds would set a new TOA balance, cannot be tested
with that system since there are none!
What we need is not a system that just runs away, but one that runs
away to a new stable state.
Cheers, Alastair.
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