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  #11  
Old August 9th 18, 11:59 AM posted to sci.astro.amateur
Gary Harnagel
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Default Latest News on Global Warming

On Wednesday, August 8, 2018 at 11:59:35 PM UTC-6, Chris.B wrote:

On Thursday, 9 August 2018 03:28:25 UTC+2, Gary Harnagel wrote:

Using simplified models for a sanity check on "more complex" one is a valid
scientific operation.


Not if it ignores every other factor.


"Every other factor" cannot ignore the basic equations of atmospheric
reflection, absorption and re-emission. MODTRAN is a well-characterized
model used by the US Air Force:

https://web.archive.org/web/20080428...et.asp?id=7915

"MODTRAN has been extensively verified and validated against FASCODE line-
by-line calculations and measurement data. In a comparison of radiance codes
for climate modeling (ICRCCM), MODTRAN was compared with three independent
interferometer measurements of up-looking radiance and the overall agreement
was excellent."

The USAF has been using MODTRAN for a quarter of a century and find it
to be quite accurate. Others use it, too. It's strange that someone who
doesn't understand it doubts it but accepts other models that he also
doesn't understand :-)
  #12  
Old August 9th 18, 12:10 PM posted to sci.astro.amateur
Gary Harnagel
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Posts: 659
Default Latest News on Global Warming

On Thursday, August 9, 2018 at 3:22:57 AM UTC-6, Martin Brown wrote:

On Tuesday, August 7, 2018 at 7:40:03 AM UTC-6, Quadibloc wrote:
The tipping point is in sight:

https://www.cbc.ca/news/technology/w...port-1.4775649


They are probably being overly pessimistic. However, I think the
incidence of wildfires in the USA and persistent drought in Australia
may yet force the climate change deniers to change their tune.


Some deny global temperature increase, but others admit it is happening
but deny CO2 et al are responsible. MODTRAN supports the latter.

It is a shame that Texas cannot be laid waste by climate change induced
catastrophes. California has been trying quite hard - they don't deserve
to bear the brunt of natures fight against the fossil fuel lobby.


That's a very biased paragraph.

http://climatemodels.uchicago.edu/modtran/

T_offset = 0, T_ground = 298.52 K, Upward heat flux = 298.52 W/m²

T_offset = 2, T_ground = 301.7 K, Upward heat flux = 307.44 W/m²

Conditions are CO2 = 400 ppm, Tropical region, No clouds

Clouds hold the heat in, but reflect more solar energy.

The model also shows that DOUBLING the CO2 concentration to 800 ppm
has a minimal effect on outgoing heat:

T_offset = 0, T_ground = 299.7 K, CO2 = 800 pp,,
Upward heat flux = 295.2 W/m²

To get the UHF back to 298.5 W/m², increase T_offset to 0.75 K..
So doubling the CO2 level increases the ground temperature by 2 K.
That doesn't look like a "tipping point."


If you believe these figures are accurate to 5 sig fig then you are no
scientist.


If you believe the IPCC results are accurate to 5 sig fig then YOU are
no scientist :-)

Don'tcha just love oversimplification for effect?
Is Big Carbon's pocket money allowance taxable?


Using simplified models for a sanity check on "more complex" one is a
valid scientific operation.


Using a model that completely ignores the thawing of permafrost and
clathrates leading to bulk methane escaping in the Siberian wilderness
will obviously not show any kind of tipping point. There is serious
hysteresis in the climate system once you go past a certain point and
the permanent ice caps and glaciers are forced into retreat.

I tormented one of the much earlier models trying to boil the oceans at
the equator by making a big step change in CO2. Even at 3K per doubling
of CO2 it would require an increase of about 2^14 to get the worst case
temperatures that high - about 6 bar of CO2 (making it impossible for
life to survive outdoors in some places is much easier 8x will do that).

Things get quite nonlinear as the equatorial seas approach boiling point
so this was pushing the model well outside reasonable bounds.

--
Regards,
Martin Brown


We're probably not concerned about what happens when the oceans boil :-)
 




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