Re: Whoops! The Atlantic Makes Trump Look EPIC In Cover Intended as a Smear

Mike Van Pelt wrote:

In article <49557f097f4606f51f485fc2bbf6e77c@www.novabbs.com>,
quadibloc  <quadibloc@gmail.com> wrote:

On Thu, 19 Sep 2024 0:08:18 +0000, Lynn McGuire wrote:
>

Chemical saturation limits EVERYTHING but is rarely taken into account.

>
Given that the proportion of carbon dioxide in the
atmosphere is measured in parts per million, I had
not thought of that as an important factor just yet.

It is dangerous to think in terms of numbers without context.  The atmosphere is saturated, or nearly so, at some wavelengths such as the UV, despite the very few ozone molecules involved.

 I think the "saturation" issue was that well below current CO2
levels, the atmosphere was already pretty much opaque to long
wave IR, so more CO2 couldn't have any significant effect.

But it still would, see below.

I've heard this asserted, and also assertions that this
was false.  One of the people asserting it was false was
Jordin Kare, who was pretty deeply involved in punching IR
lasers through the atmosphere, so I suspect it's false.

Oh, it's false. Searching for "atmospheric infrared absorption" should call up some graphs of  this.  Some wavelengths are saturated, or nearly so, others are not.
The black body temperature of the earth is 255.  Thus the average emission temperature of the earth's IR must be 255 for conservation of energy (plus or minus a small amount as the earth's temperature changes).
If the atmosphere were opaque to IR at all wavelengths, the outgoing IR signal measured by satellites would be very cold, averaging 255 as all the photons would escape to space only from high cold altitudes.  But in fact it is not, and at some places is more like 280, or ground temperature, as some IR escapes to space directly (in what is called the "atmospheric window:).
But in fact even if  the atmosphere was saturated it would not mean that adding more CO2 would have no effect on temperature.
The important factor in retaining heat is the mean free path length of a photon.  The shorter it is, the harder it is for energy to escape and the longer the time that the energy spends in the atmosphere.
Solar models use  the same concept, though they're talking about much shorter wavelength radiation. There's nothing remotely controversial about this.  If our climate models are wrong in this, then the sun doesn't shine either.
William Hyde