Re: [Phys-l] global temperatures

[kyle forinash <kforinas@ius.edu>]

HI

Some factoids (mostly from the IPCC). Although the total annual average 
insolation remains constant for the earth over hundreds of thousands of 
years (even including orbit changes- and changes in sun intensity occur 
much slower), the LOCAL change at 60deg latitude is a seasonal variation 
of around ~400W/m^2. It is this LOCAL variance which is thought to give 
rise to changes from ice age to interglacial (carbon dioxide appears to 
act as a feedback mechanism for this change, rising in warm climates and 
falling in cool climates).

The solar variation over the past 11,000 years is thought to be around 
0.02W/m^2, sunspots about 1W/m^2. Some evidence links sunspots to 
seasonal variations in temperature. Aerosols due to volcanoes are 
estimated to cause less than -1W/m^2, still enough to see a global drop 
in temperature of ~1C the year following a major eruption.

As mentioned, CO2 is only 0.03% of the atmosphere, water vapor 0.48% 
(not including raindrops, ice etc). However the total atmospheric 
forcing is thought to be approximately 23W/m^2 due to CO2, 56W/m^2 due 
to water vapor and this results in the earth being 33C warmer if not for 
this forcing as can be calculated using blackbody radiation equilibrium. 
So yes, CO2 is a small part of the atmosphere but a significant part of 
global temperature.

The IPCC says ~1.5W/m^2 of the CO2 forcing is human caused, another 
0.5W/m^2 from methane. Comparing a 2W/m^2 global total forcing over 
200years to the 400W/m^2 local annual variation due to orbital tilt 
makes man made forcing hard to detect. On the other hand claiming the 
2W/m^2 man made forcing has changed the global temperature by ~1C is 
pretty close to what is observed from short term volcano forcing of 
-2W/m^2.

The hydrological cycle is on the order of weeks; water vapor levels 
quickly adjust to temperature changes. The carbon cycle is on the order 
of a century; changes in CO2 levels are with us for a long time. We will 
live with our mistakes for quite a while.

kyle
> ------------------------------
>
> Message: 14
> Date: Fri, 1 May 2009 07:38:07 -0500 (CDT)
> From: Jack Uretsky <jlu@hep.anl.gov>
> Subject: Re: [Phys-l] global temperatures
> To: Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu>
> Message-ID: <Pine.LNX.4.64.0905010730580.21553@theory.hep.anl.gov>
> Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
>
> HI all-
> What juatifies the "only" on the ".03%* .  "Only" as compared with what"
>                                         regarda,
>                                                 Jack
>
>
> On Mon, 6 Apr 2009, Bill Nettles wrote:
>
> > We would do well to remember that the CO2 level is only around 0.03% (give or take 0.001%) by volume of the atmosphere, and the actual amount of thermal "forcing" caused by changes in CO2 levels is subject to reasonable debate. Yes, caution is an admirable quantity, but fear-mongering is not ( not accusing you, kyle, but there are notable influential people who scream "change is bad/good" depending on how it serves their financial and political budgets. I think there are a lot of correlations that are being suspected as causes.
> >
> > Sometimes cures produce their own problems, such as the case of staph bacteria and antibiotics.
> >
> > Bill
> >
> > > > > kyle forinash <kforinas@ius.edu> 4/5/2009 10:16 am >>>
> > HI
> >
> > I also think caution is advised about global warming claims but have
> > arrived at the opposite conclusion as some recent posts would seem to
> > imply. There doesn't seem to be any doubt that CO2 levels are up by 30%
> > and are continuing to go up. There doesn't seem to be any doubt as to
> > the source of this CO2. Shouldn't we be cautious about performing such
> > an experiment on the atmosphere, particularly if we aren't exactly sure
> > what is happening?
> >
> > Other:
> > http://www.guardian.co.uk/world/2009/apr/05/ice-shelf-wilkins-antarctic
> >
> > kyle
> > _______________________________________________
> > Forum for Physics Educators
> > Phys-l@carnot.physics.buffalo.edu
> > https://carnot.physics.buffalo.edu/mailman/listinfo/phys-l
> >
> > _______________________________________________

--
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 "When applied to material things,
the term "sustainable growth" is an oxymoron."
	Albert Bartlett

 kyle forinash   812-941-2039
  kforinas@ius.edu
  http://Physics.ius.edu/
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