[EMAIL PROTECTED] wrote:
>> The atmosphere is pretty tightly coupled to the ocean, especially the
>> surface. I suppose it's possible that some altitudes would be affected
>> more significantly, depending on the details of aerosol behaviour (a
>> point that I'm not at all expert on).
>
> I've been thinking quite a bit about thermal lag, it's an area that I
> like, because of my background as a chemical engineer.
>
> A good comparison ought to be seasonal changes. Over a day forcing
> changes by about 1000 W/m2, over a season I don't know exactly, order
> of magnitude wise it ought to be around 200 W/m2.
>
> In Siberia, seasonal temperature changes I think approach 50C, in
> England it's more like 20C.
I think the UK is more like 10C and a global average is roughly half
that. This would suggest that on the global scale the effect would be
very much at (below) the bottom end of your range. Of course I agree
that on a local basis the elimination of all aerosols could have rather
larger effects.
>> Well unless one postulates an extremely high sensitivity to such forcing
>> (but not to other forcings), one would expect the warming to be
>> levelling off - and there's no sign of that except through some rather
>> specious cherry-picking vis a vis 1998...
>
> I suppose, playing devil's advocate here, the recent lack of levelling
> off might be due to say the declining aerosol forcing Michael Tobis
> mentions ("the trend in aerosol emissions from Chinese power plants is
> sharply downward").
I don't think there is any suggestion that aerosols globally have
actually declined significantly (the emissions rate per power output may
have improved, but total power has increased). Crowley's forcing data
has aerosols monotonically increasing to 1998.
>
> Not being a climate scientist I am a little confused about what the
> concept of forcing really means in the case of cosmic rays. My
> understanding is that the forcing is measured in W/m2 at the ground,
> assuming no feedbacks from water vapour, clouds etc.
Roughly speaking it is at the top of the atmosphere assuming everything
else is held fixed (although there are a few variants of "top" and
"everything else").
James
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