C02 as a greenhouse gas

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Geoff

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Jun 18, 2004, 9:56:56 AM6/18/04
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Water vapor constitutes 97% of atmospheric greenhouse gases 3% C02
with trace amounts of methane and ozone. What are the relative
strengths of these gases to trap heat in the atmosphere? (For example
is C02 5 times more efficient as a greenhouse gas than water vapor, or
all they all the same?)

Thanks

Geoff


Ian St. John

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Jun 18, 2004, 10:34:00 AM6/18/04
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It is not that simple. Every GHG has a different 'global warming potential'
based on both it's IR windows and it's concentration and it is not even
linear. Beyond that the different GHGs tend to 'steal the other guys
thunder'. That is, an IR photon that *would* have been trapped by X may be
trapped by Y first. You can only look at it from the point of view of 'what
if there were no <...> and see how much that would affect the total.

http://www.radix.net/~bobg/climate/halpern.trap.html
Table 2.2 Contributions of atmospheric ratiation absorbers
to thermal trapping

Species removed % trapped radiation remaining
All 0
H2O CO2 O3 50
H2O 64
Clouds 86
CO2 88
O3 97
None 100
Data from Rev. Geophys. & Space Sci. 16 (1978) 465

Beyond that we also have to consider the 'persistence' of the GHGs. If you
removed ALL of the CO2, the water would eventually freeze out of the
atmosphere and you would be left with a negligeable (3% from O3) GH effect.
That is because the concentration of H2O is dependent on temperature (
feedback effect ) and it's atmosphereic lifetime is at most a few days. As a
CAUSE of the current surface temperature, water is negligeable. As a
*contributor* to the greenhouse effect, it is substantial ( though not that
much bigger than CO2. )

>
> Thanks
>
> Geoff


Geoff

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Jun 18, 2004, 11:39:22 AM6/18/04
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"Ian St. John" <ist...@noemail.ca> wrote in message
news:t3DAc.39098$nY.12...@news20.bellglobal.com...

Given this set of numbers what is the response to the argument that
since C02 is such a small fraction of the greenhouse gas potential
(from my reading O3 is about twice as efficient as H2O, CO2 about 35%
more efficient) and that there is nothing to do about water vapour
anyway, why spend so much time, effort and resources on something that
accounts for a very small percentage of the atmosphere's capacity to
create a greenhouse effect?

Thanks
Geoff

<snip>


David Ball

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Jun 18, 2004, 12:30:08 PM6/18/04
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On Fri, 18 Jun 2004 09:39:22 -0600, "Geoff" <gghi...@nospam.ca>
wrote:

Because CO2, Methane, etc have a direct influence on the
radiation balance. Water vapour has a secondary effect through
feedback processes. CO2 causes the temperature of the planet to
change. This changes other atmospheric processes like evaporation,
advection, convection, ... which then alter the water vapour levels in
the atmosphere. The real problem is not the concentration of the
primary GHG but the rate that they are changing.

w...@bas.ac.uk

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Jun 18, 2004, 12:47:45 PM6/18/04
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Um, did you ever stop to wonder where you got that 97% figure from, and
if it was correct or not? It isn't. 50% is more like it.

http://en.wikipedia.org/wiki/Greenhouse_effect

-W.

--
William M Connolley | w...@bas.ac.uk | http://www.antarctica.ac.uk/met/wmc/
Climate Modeller, British Antarctic Survey | Disclaimer: I speak for myself
I'm a .signature virus! copy me into your .signature file & help me spread!

Thomas Palm

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Jun 18, 2004, 2:11:03 PM6/18/04
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"Geoff" <gghi...@nospam.ca> wrote in news:cav2bo$4tg$1...@news.ucalgary.ca:

> "Ian St. John" <ist...@noemail.ca> wrote in message

>> http://www.radix.net/~bobg/climate/halpern.trap.html


>> Table 2.2 Contributions of atmospheric ratiation absorbers
>> to thermal trapping
>>
>> Species removed % trapped radiation remaining
>> All 0
>> H2O CO2 O3 50
>> H2O 64
>> Clouds 86
>> CO2 88
>> O3 97
>> None 100
>> Data from Rev. Geophys. & Space Sci. 16 (1978) 465
>
> Given this set of numbers what is the response to the argument that
> since C02 is such a small fraction of the greenhouse gas potential
> (from my reading O3 is about twice as efficient as H2O, CO2 about 35%
> more efficient) and that there is nothing to do about water vapour
> anyway, why spend so much time, effort and resources on something that
> accounts for a very small percentage of the atmosphere's capacity to
> create a greenhouse effect?

That is a bogus argument created by people who just don't want to do
anything about climate change, often because they are in the business of
emitting CO2. We may not be able to control water vapor directly, but warm
air in general contains more water so a small warming from CO2 will be
amplified as the water contents of the atmosphere increases. It is a lot
more useful to consider the question: will adding more CO2 cause enough
climate change to be a problem, and the answer to that question is yes.

You have to keep in mind that the total greehouse effect on Earth is about
35 C so even a fairly small change of it is going to be significant.

charliew2

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Jun 18, 2004, 2:49:55 PM6/18/04
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Thomas, water vapor is definitely different than CO2. Water vapor acts as a
heat transfer medium, meaning that it condenses several thousand feed up in
the atmosphere, releasing its heat of vaporization as it radiates IR
radiation into outer space. It also forms clouds as it is condensing,
increasing the albedo of earth. The point? Everyone focuses ONLY on the
fact that water vapor is a positive feedback relative to CO2 increases. In
point of fact, if this logic were true, ANY small temperature increase would
cause a fairly quick and rapid positive feedback runaway in global
temperatures. In my opinion, it's time to consider that there are also
negative feedbacks involved regarding water vapor.

Lloyd Parker

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Jun 18, 2004, 11:04:10 AM6/18/04
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In article <cav2bo$4tg$1...@news.ucalgary.ca>,
CO2 is the one that's increasing artificially, due to human activities; thus,
it's the one that's mostly responsible for the addtional warming. In
addition, since it's the one people are responsible for, it's the one people
can do something about.

A virus may raise your body temp. from 310 K ro 314 K. This seems like an
awfully small %, doesn't it? But it's enough to kill you (106 F).

Lloyd Parker

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Jun 18, 2004, 11:01:40 AM6/18/04
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In article <causbj$1tq$1...@news.ucalgary.ca>,
Not really relevant to the current warming because:

1. Water is easily and quickly removed from the atmosphere by nature (as
rain). So it's in balance. It's CO2 (along with CH4, CFC, etc.) that's
increasing.

2. We're talking about the _added_ warming that's occurring, not the natural
warming due to the natural greenhouse effect.

Phil Hays

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Jun 18, 2004, 3:23:01 PM6/18/04
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"charliew2" <char...@ev1.net> wrote:
>Thomas Palm wrote:
>> "Geoff" <gghi...@nospam.ca> wrote:
>>> why spend so much time, effort and resources on something
>>> that accounts for a very small percentage of the atmosphere's
>>> capacity to create a greenhouse effect?

>> That is a bogus argument created by people who just don't want to do
>> anything about climate change, often because they are in the business
>> of emitting CO2. We may not be able to control water vapor directly,
>> but warm air in general contains more water so a small warming from
>> CO2 will be amplified as the water contents of the atmosphere
>> increases.

>Thomas, water vapor is definitely different than CO2. Water vapor acts as a
>heat transfer medium, meaning that it condenses several thousand feed up in
>the atmosphere, releasing its heat of vaporization as it radiates IR
>radiation into outer space. It also forms clouds as it is condensing,
>increasing the albedo of earth. The point? Everyone focuses ONLY on the
>fact that water vapor is a positive feedback relative to CO2 increases. In
>point of fact, if this logic were true, ANY small temperature increase would
>cause a fairly quick and rapid positive feedback runaway in global
>temperatures. In my opinion, it's time to consider that there are also
>negative feedbacks involved regarding water vapor.

Positive feedback doesn't mean instability or runaway. Charlie, you
should have enough control systems background to understand that. If
you don't, then crack open the books and look up "Nyquist stability
criterion". Or be net aware and google for it:

http://www.chem.mtu.edu/~tbco/cm416/nyquist.html


--
Phil Hays
Phil_hays at posting domain should work for email

Thomas Palm

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Jun 18, 2004, 5:10:19 PM6/18/04
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"charliew2" <char...@ev1.net> wrote in
news:10d6edv...@corp.supernews.com:

> Thomas Palm wrote:
>>> Given this set of numbers what is the response to the argument that
>>> since C02 is such a small fraction of the greenhouse gas potential
>>> (from my reading O3 is about twice as efficient as H2O, CO2 about
>>> 35% more efficient) and that there is nothing to do about water
>>> vapour anyway, why spend so much time, effort and resources on
>>> something that accounts for a very small percentage of the
>>> atmosphere's capacity to create a greenhouse effect?
>>
>> That is a bogus argument created by people who just don't want to do
>> anything about climate change, often because they are in the business
>> of emitting CO2. We may not be able to control water vapor directly,
>> but warm air in general contains more water so a small warming from
>> CO2 will be amplified as the water contents of the atmosphere
>> increases.
>
> Thomas, water vapor is definitely different than CO2. Water vapor
> acts as a heat transfer medium, meaning that it condenses several
> thousand feed up in the atmosphere, releasing its heat of vaporization
> as it radiates IR radiation into outer space.

This is included in all climate models. Any short description is going to
have to ignore some effects, as you prove in your next sentence.

> It also forms clouds as
> it is condensing, increasing the albedo of earth.

If you want to drag clouds into the picture you should mention that clouds
also reflect IR from the ground keeping heat in. Whether the net effect is
positive or negative depends on the altitude and thickness of the clouds.

> The point?
> Everyone focuses ONLY on the fact that water vapor is a positive
> feedback relative to CO2 increases. In point of fact, if this logic
> were true, ANY small temperature increase would cause a fairly quick
> and rapid positive feedback runaway in global temperatures. In my
> opinion, it's time to consider that there are also negative feedbacks
> involved regarding water vapor.

Everyone making models know all this and do not concentrate only on the
positive feedbacks. As Phil Hays already pointed out, a positive feedback
doesn't mean instability. I've seen somewhere that for the simplest 1D
models without clouds the system does become unstable for a wet surface
about ~28 C due to the non-linearity of water vapor concentration, but
GCM:s do take lots of other effects into accounts making this instability
disappear.

Ian St. John

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Jun 18, 2004, 5:59:04 PM6/18/04
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You clipped the point that H20 is temperature dependent and not 'persistent'
so it cannot be a *cause* of global warming so much as a feedback to
existing warming.

> (from my reading O3 is about twice as efficient as H2O, CO2 about 35%
> more efficient)

Note that, because of the competition between different species, the
variations in concentration, and the 'diminishing returns' of high
concentration the 'marginal effect' of changes in amount are different for
each species and for their current concentrations. You cannot say how
efficient their GWP is except at specified concentrations.

> and that there is nothing to do about water vapour anyway,

One must include it to understand the whole picture, even if it cannot be a
control on the process.

> why spend so much time, effort and resources on something that
> accounts for a very small percentage of the atmosphere's capacity to
> create a greenhouse effect?

I'm not sure I follow. Based on current concentrations ( see chart above )

O3 is 3%
CO2 is 12%
H20 is 36%

Obviously we could make more change in GW by a small 'percentage' change in
the H2O concentration, but this is totally impractical since we have no way
to control evaporation, and while it forms a large factor in the GW effect,
the MASS of water that provides this change is HUGE compared to CO2. Water
vapor forms 2% to 3% of the atmosphere, say 25,000 ppm! To change it by 10%
( equivalent to reducing CO2 by 30% ) you would need to remove 2,500 ppm of
water, a huge feat even if we had the technology to do it and it would last
for, at most, two days before returning to normal from evaporation. Totally
impossible to keep up that kind of effort for long.

To attack it from the point of view of O3 is equally silly, since, if we
could do anythign at ALL about O3, we would have eliminated it to clean up
the smog of the '70s. It is created by photodissociation of O2 by UV rays
and unless we wanted to shade the planet from the sun, we are going to have
to live with it.

However, CO2 is both small in mass, as is an obvious targets, since not only
are changes in the concentration 'persistent' for hundreds of years, and the
quantities that need to be manipulated much smaller, but we have a very good
technological grip on all the processes that are changing the concentration
today. I.e. fossil fuel combustion.

Is this too deep for you?


>
> Thanks
> Geoff
>
> <snip>


Michael Tobis

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Jun 18, 2004, 6:17:30 PM6/18/04
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"charliew2" <char...@ev1.net> wrote in message news:<10d6edv...@corp.supernews.com>...

> The point? Everyone focuses ONLY on the
> fact that water vapor is a positive feedback relative to CO2 increases. In
> point of fact, if this logic were true, ANY small temperature increase would
> cause a fairly quick and rapid positive feedback runaway in global
> temperatures.

Not all amplifiers are unstable.

> In my opinion, it's time to consider that there are also
> negative feedbacks involved regarding water vapor.

Well, there are some attenuating feedbacks regarding clouds, but the
water vapor greenhouse feedback dominates.

Note that even weather models need to get this particular feedback
right, because water vapor enhancement of radiative forcing is big
enough and fast enough to affect weather on weather prediction time
scales. So we have plenty of evidence that we have this feedback about
right.

It's about twenty years too late to be arguing on this point. Not that
that would stop anyone. (sigh)

mt

Ian St. John

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Jun 18, 2004, 6:20:05 PM6/18/04
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In many ways.

> Water vapor acts as a heat transfer medium, meaning that it condenses
> several thousand feed up in the atmosphere, releasing its heat of
> vaporization as it radiates IR radiation into outer space.

The change in density for a specific change in altitude determines when a
packet of air is 'unstable' and will drive convection. This 'lapse rate' is
pretty much set in stone by the physics of air and water vapor, and their
densities. While changes in convection are possible, they do not really
have much effect on the global temperature since even at the top of the
troposphere, the IR is still mostly returned to the earth. Only at the
'equipotential point' where the atmosphere is thin enough to stop convection
forces is it possible to have a radiative emission that balances incoming
solar radiation and so the temperature at the surface is set by the height
of this 'radiating surface' times the lapse rate to the ground. Change in
heat transfer in the convective ( troposphere ) part of the atmosphere will
have ZERO effect on global warming.

> It also
> forms clouds as it is condensing, increasing the albedo of earth.

http://earthobservatory.nasa.gov/Study/Iris/iris2.html
"Based upon CERES data, Lin's team concluded that the reduction in cloudy,
moist skies allows extra sunlight to warm the surface by up to 1.8 Watts per
square meter-a small but positive net energy flux (Lin et al. 2001).
"Our results are based upon actual observations that are used to drive
global climate models," Lin concludes. "And when we use actual observations
from CERES we find that the Iris Hypothesis won't work.""


> The point? Everyone focuses ONLY on the fact that water vapor is a
> positive feedback relative to CO2 increases.

Nope. They focus on the 'climate sensitivity' which subsumes changes in
cloud cover, water vapor feedback, and albedo to result in a 'fudge factor'
for how all other processes react to a forcing.

> In point of fact, if
> this logic were true, ANY small temperature increase would cause a
> fairly quick and rapid positive feedback runaway in global
> temperatures.

Now Charliie!. I am beginning to think that you are uneducated, much less an
engineer. You have to have a 'positive feedback' factor above unity to have
a 'runaway'. The feedback from water is about 0.6 so it causes a change of
about 1.5 times the original forcing ( series summation ).

> In my opinion, it's time to consider that there are
> also negative feedbacks involved regarding water vapor.

In my opinion, it is time you stopped adding stupid opinions and went back
to school to get your GED.

P.S. yes they MAY be negative feedbacks with water vapor. When we find one,
we will let you know... In the meantime, don't let your imagination run away
with you.

charliew2

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Jun 18, 2004, 9:24:02 PM6/18/04
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OK. I'll rephrase. Positive feedback, in the absence of offsetting
negative feedbacks, leads to runaway. The talk in this newsgroup about the
positive feedback from water vapor IMPLIES that there are only positive
feedbacks. This simply isn't true, whether or not you use Nyquist in your
argument. Naturally, the public hasn't a clue, and such "grandstanding"
looks to me like attempts to use scare tactics to win your argument. Tsk,
tsk!

charliew2

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Jun 18, 2004, 9:30:32 PM6/18/04
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I'm not trying to "stop anyone". I'm arguing that a layman will tend to
conclude that the comments about water vapor being a positive feedback means
that CO2 increases causing higher temperatures necessarily means some type
of runaway temperature increase via positive feedback from water vapor
(e.g., Roger Coppock's assumption of an exponential temperature increase).
Runaways just flat ain't gonna happen, and the public needs to hear that.


Steve Schulin

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Jun 18, 2004, 9:29:01 PM6/18/04
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In article <bcaf804.04061...@posting.google.com>,
m...@3planes.com (Michael Tobis) wrote:

Fortunately, we have the last about 20 years experience to help
understand. Karner [J. Geophys. Res., 10.1029/2001JD002024, 2002]
concludes that negative feedback has dominated the climate system during
1979-2001. Here's how he puts it in the final paragraph of conclusions
section:

"The revealed antipersistence in the lower tropospheric temperature
increments does not support the science of global warming developed by
IPCC [1996]. Negative long-range correlation of the increments during
last 22 years means that negative feedback has been dominating in the
Earth climate system during that period. The result is opposite to
suggestion of Mitchell [1989] about domination of a positive cumulative
feedback after a forced temperature change. Dominating negative feedback
also shows that the period for CO2 induced climate change has not
started during the last 22 years. Increasing concentration of greenhouse
gases in the Earth atmosphere appeared to produce too weak forcing in
order to dominate in the Earth climate system. Estimate of the adjusted
radiative forcing due to changes in the concentrations of the so-called
greenhouse gases since preindustrial times is 2.45 Wm-2 [IPCC, 1996]. If
the increase was during 15 years, its annual increment (0.16 Wm-2) would
be comparable to standard deviation of the daily increment of solar
forcing at the top of the atmosphere (0.18 Wm-2). The observed global
warming in surface air temperature series [Jones et al., 1999] is more
likely produced due to overall nonstationary variability of the Earth
climate system under anti-persistent solar forcing."

Very truly,

Steve Schulin
http://www.nuclear.com

Jim Norton

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Jun 18, 2004, 10:27:33 PM6/18/04
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Steven Milloy, in his latest ignorant rant, clames much the same thing, with
somewhat different numbers. He then claims that most of the carbon dioxide is
from natural sources, so humans aren't causing global warming at all. Of
course he neglets to mention that the increase in CO2 is from people:

http://www.foxnews.com/story/0,2933,123013,00.html

==============================


Anti-environmental myths
http://info-pollution.com/myths.htm
Practical skepticism
http://info-pollution.com/skeptic.htm

Ian St. John

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Jun 18, 2004, 10:26:42 PM6/18/04
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charliew2 wrote:
> Phil Hays wrote:
<snip>

>> Positive feedback doesn't mean instability or runaway.
>
> OK. I'll rephrase. Positive feedback, in the absence of offsetting
> negative feedbacks, leads to runaway.

Charlie. Your ignorance is exposed. Only a feedback greater than unity
causes a 'runaway'. A negative feedback can ALSO be a 'runaway' in the
opposite direction. The reason that water vapor doesn't cause a 'runaway' is
that he positive feedback factor is 0.6, less than unity.

Where did you go to school and which grade was your highest grade actually
passed? Three? Four?


Phil Hays

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Jun 18, 2004, 10:51:17 PM6/18/04
to

I would not expect that a controls engineer would make such a blunder.
Explain using math, please. Please do it using the Nyquist stability
criterion, as I would expect a control engineer to understand. Or use
either of the first or second methods of Liapunov.

Or try this simple discrete time example:

X(t+1) := k*X(t) + Y(t)

This is a first order discrete time system. If k is negative, the
feedback is negative. If k is positive, the feedback is positive.
What range of k is stable?

I'll start by giving a few free hints:

k < -1 is unstable. Try -1.1 and find out.

k = .1 is quite stable. Try it and find out. This is a simple
example that anyone that can add and multiply can verify for
themselves that positive feedback does not meen runaway.

Now, do you want to buy a clue?


> The talk in this newsgroup about the
>positive feedback from water vapor IMPLIES that there are only positive
>feedbacks. This simply isn't true, whether or not you use Nyquist in your
>argument. Naturally, the public hasn't a clue, and such "grandstanding"
>looks to me like attempts to use scare tactics to win your argument. Tsk,
>tsk!

Clues for sale or rent,
hints for just fifty cents.
No trolls, no spam, no twits.
Only fools smoke them cigarettes.

Josh Halpern

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Jun 18, 2004, 11:56:33 PM6/18/04
to

w...@bas.ac.uk wrote:

>Geoff <gghi...@nospam.ca> wrote:
>
>
>>Water vapor constitutes 97% of atmospheric greenhouse gases 3% C02
>>with trace amounts of methane and ozone. What are the relative
>>strengths of these gases to trap heat in the atmosphere? (For example
>>is C02 5 times more efficient as a greenhouse gas than water vapor, or
>>all they all the same?)
>>
>>
>
>Um, did you ever stop to wonder where you got that 97% figure from, and
>if it was correct or not? It isn't. 50% is more like it.
>
>http://en.wikipedia.org/wiki/Greenhouse_effect
>

Let me point out that talking about "efficiency as a greenhouse gas" can
be misleading. Such efficiency is usually measured on a per molecule
basis.
The agreed name for it is "greenhouse potential" and CO2 is arbitrarily
assigned as unity. The efficiency as a greenhouse gas depends on the
ability to absorb IR light withing the emission envelope of a ~ 290K black
body and the atmospheric lifetime, as well as various overlaps with other
components

The real high GWP are from perfluorinated compounds, and thereby lies
some interesting tales.

Here is a table
http://www.ldeo.columbia.edu/edu/dees/ees/climate/slides/table_2.html

Since the effect of any component depends on the concentration of that
component you can have something with a small greenhouse potential and
a large concentration, having a large effect.

Since water vapor concentration is controlled by temperature and not
emission, it is not generally included in such tables.

josh halpern

>
>-W.
>
>
>

David Ball

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Jun 19, 2004, 1:01:00 AM6/19/04
to
On Fri, 18 Jun 2004 20:24:02 -0500, "charliew2" <char...@ev1.net>
wrote:

Charlie, you're popping off again without having a clue what
you're talking about. Cloud produces both a positive and a negative
feedback depending on the time of year. What's worse is that you don't
have a clue.

David Ball

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Jun 19, 2004, 1:02:05 AM6/19/04
to

Steve, if I saw what you're pushing lying in the street, I'd
step over it.

charliew2

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Jun 19, 2004, 1:56:05 AM6/19/04
to

How about I buy you a clue from a simple, real world (not college textbook,
oversimplified) example? Let's say that you have a cruise control on your
car. You speed up to the desired speed, and press the button to engage the
speed control. When the speed drops below the setpoint, the controller lets
up on the accelerator pedal, and when you go faster than desired, the
controller pushes down on the accelerator pedal. In this instance, the
controller acts such that it adds to the deviation from setpoint, which is a
classic example of positive feedback.

I have to conclude that my definition of positive feedback is different than
yours. Your simple example is talking about stability, which is distinctly
different than positive feedback. Negative feedback systems can be stable
or unstable, depending on what the overall "loop" gain is (combination of
process gain and controller gain). From my experience, ALL positive
feedback systems are unstable. Of course, I wouldn't expect you to
understand the subtle difference.


>
>> The talk in this newsgroup about the
>> positive feedback from water vapor IMPLIES that there are only
>> positive feedbacks. This simply isn't true, whether or not you use
>> Nyquist in your argument. Naturally, the public hasn't a clue, and
>> such "grandstanding" looks to me like attempts to use scare tactics
>> to win your argument. Tsk, tsk!
>
> Clues for sale or rent,
> hints for just fifty cents.
> No trolls, no spam, no twits.
> Only fools smoke them cigarettes.

Indeed.


Thomas Palm

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Jun 19, 2004, 2:42:18 AM6/19/04
to
"charliew2" <char...@ev1.net> wrote in
news:10d75tm...@corp.supernews.com:
> I'm not trying to "stop anyone". I'm arguing that a layman will tend
> to conclude that the comments about water vapor being a positive
> feedback means that CO2 increases causing higher temperatures
> necessarily means some type of runaway temperature increase via
> positive feedback from water vapor (e.g., Roger Coppock's assumption
> of an exponential temperature increase). Runaways just flat ain't
> gonna happen, and the public needs to hear that.

Nope, that was not what you were arguing or you'd have said so from the
start. You were just into your usual game of trying to give the impression
that everyone else is overstating the problem. When you said that "it's

time to consider that there are also negative feedbacks involved regarding

water vapor." you basically accused everyone else of being fools or
dishonest for not having done so. As it is clear you just don't know very
much about the climate it would be better if you had a somewhat less
arrogant attitude.

As for the feedback, what you fail to take into account in your fear about
a runaway greenhouse effect is the stabilizing effect of the T^4 dependence
on thermal radiation from Earth, which provides a strong negative feedback.
That way you can have positive feedback from water wapor and still not have
a runaway effect.

James Annan

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Jun 19, 2004, 5:56:44 AM6/19/04
to
charliew2 wrote:

> I have to conclude that my definition of positive feedback is different than
> yours.

And, surprise surprise, yours is bogus, incomplete, or plain wrong, or
some combination of all three.

Which is pretty much par for the course for your "contributions" to this
newsgroup.

James
--
If I have seen further than others, it is
by treading on the toes of giants.
http://www.ne.jp/asahi/julesandjames/home/

Phil Hays

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Jun 19, 2004, 9:39:50 AM6/19/04
to

And the answer is??


>> I'll start by giving a few free hints:
>>
>> k < -1 is unstable. Try -1.1 and find out.
>>
>> k = .1 is quite stable. Try it and find out. This is a simple
>> example that anyone that can add and multiply can verify for
>> themselves that positive feedback does not meen runaway.

Did you verify that positive k was stable, at least for k = .1?


>How about I buy you a clue from a simple, real world (not college textbook,
>oversimplified) example? Let's say that you have a cruise control on your
>car. You speed up to the desired speed, and press the button to engage the
>speed control. When the speed drops below the setpoint, the controller lets
>up on the accelerator pedal, and when you go faster than desired, the
>controller pushes down on the accelerator pedal. In this instance, the
>controller acts such that it adds to the deviation from setpoint, which is a
>classic example of positive feedback.

I could again ask you to treat this as an engineering problem. Give
your definitions. Write the equations. But would you do that? Could
you do that?

Or I could write about any of several well known systems that use
positive feedback, like a regenerative radio receiver.

Or I could point out that this "cruise control" example of yours could
be the same as my simple example if the controller was discrete time
and was slow enough. In other words, the "cruise control" would take
a speed measurement once every n seconds, then set the accelerator
based on that measurement, where n is large enough to have the car to
have responded to the change in throttle.

Or I could work through a more complex example.


>I have to conclude that my definition of positive feedback is different than
>yours.

If so, then your definition doesn't match your observations about
water vapor.


> Your simple example is talking about stability, which is distinctly
>different than positive feedback. Negative feedback systems can be stable
>or unstable, depending on what the overall "loop" gain is (combination of
>process gain and controller gain).

You told me that positive feedback is unstable. I gave you an example
of a system with positive feedback that was stable. What is subtle
about that?


> From my experience, ALL positive
>feedback systems are unstable.

I've used a regenerative radio receiver.


> Of course, I wouldn't expect you to
>understand the subtle difference.

Did you work my example? Need a hint?


Clues for sale or rent,
hints for just fifty cents.
No trolls, no spam, no twits.
Only fools smoke them cigarettes.

Steve Schulin

unread,
Jun 19, 2004, 10:28:37 AM6/19/04
to
In article <e5i7d09v8kohmt32f...@4ax.com>,
David Ball <wra...@mb.sympatico.ca> wrote:

While Mr. Ball's tilt may seem a constant, his reply here may be
indicative of a wobble. Compare with his tactics desribed back in July
2001:

Ball "Control Triangle" Tactic A:

When someone posts something from other than peer-reviewed journal, Mr.
Ball is wont to comment disparagingly on its heredity, while ignoring
any substantive points. Such is the case with an article posted to start
the thread titled "Climate models cannot yet successfully simulate
present climate conditions [Baliunas]". That thread is archived at
http://groups.google.com/groups?q=schulin+baliunas+models&hl=en&safe=off&
rnum=1&selm=75b8395d.0107070327.1cf14130%40posting.google.com

Mr. Ball didn't actually participate in that thread. This of course was
his right. But that didn't stop him from commenting on it with a series
of insults and quibbles, ignoring all the examples of how poor the two
models used in impacts assessment performed, in a different thread,
archived at
http://groups.google.com/groups?hl=en&safe=off&th=13a64710c7f322b4,73&see
km=9iskn8%245cvc%241%40newssvr06-en0.news.prodigy.com#p

He called the article "stupid", "nonsense", and opined "Most people who
know better realize the piece from Ms. Baliunas for what it is." He
noted the author's charged language. He wondered aloud if I had learned
propaganda techniques at her knee. But not once did he address the
obvious ridiculousness of predicting impacts with models that don't even
stay within 200% on precipitation or 10?F on temperature.

Ball "Control Triangle" Tactic B:

When someone posts something from peer-reviewed literature, Mr. Ball is
wont to comment disparagingly on the poster's "appeal to authority". The
most incredible example of this is how he has, to this day, ignored the
paragraphs from the NRC committee report that were posted in direct
response to his question "Please explain your reservations on climate
models and provide some insights into how such models can be improved."
That thread is archived
http://groups.google.com/groups?hl=en&safe=off&th=13a64710c7f322b4,76&see
km=75b8395d.0107191438.4e757df3%40posting.google.com#p

Ball "Control Triangle" Tactic C:

When someone makes an unreferenced comment, Mr. Ball is as wont to call
poster names as to demand citation. If you choose to bring up a
citation, he belittles you for dealving into matters too complex for
mere interested citizens to understand. If you don't, he claims victory
by your silence.

--- END OF EXCERPT FROM JULY 2001 POST ---

Very truly,

BallB...@nuclear.com
http://www.nuclear.com

Eric Swanson

unread,
Jun 19, 2004, 10:33:07 AM6/19/04
to
In article <10d7lg9...@corp.supernews.com>, char...@ev1.net says...

>
>Phil Hays wrote:
>> "charliew2" <char...@ev1.net> wrote:
[cut]

>How about I buy you a clue from a simple, real world (not college textbook,
>oversimplified) example? Let's say that you have a cruise control on your
>car. You speed up to the desired speed, and press the button to engage the
>speed control. When the speed drops below the setpoint, the controller lets
>up on the accelerator pedal, and when you go faster than desired, the
>controller pushes down on the accelerator pedal. In this instance, the
>controller acts such that it adds to the deviation from setpoint, which is a
>classic example of positive feedback.

Your example is confusing at best. The fact that the entire system is working
against a large drag is lost in your description. The forward loop is the
"amplifier" of the engine working against that drag. The feedback is the
difference between the set point and actual speeds, thus, it's negative.
There is a minus sign in the summing junction, if you will, thus the low speed
produces a positive signal into the controller, increasing the power output.
If the speed exceeded the set point, the signal from the summing junction would
be negative.

But, does your controller actuate the brake when the speed becomes too great?
Not likely. At highway speeds on gentle slopes, the dissipation from air
drag is often enough to slow the vehicle. Some speed controllers are unstable
and tend to "oscillate" under certain conditions. Consider going down a hill
with a slope for which the vehicle would have a terminal velocity slightly
below the set point. Then, the controller would boost the speed to a
point above the set point, then shut off until the speed slows below the
set point. The result would be some "hunting", ie, oscillation, the severity
of which would depend upon the time constants or delay in the controller.

>I have to conclude that my definition of positive feedback is different than
>yours. Your simple example is talking about stability, which is distinctly
>different than positive feedback. Negative feedback systems can be stable
>or unstable, depending on what the overall "loop" gain is (combination of
>process gain and controller gain). From my experience, ALL positive
>feedback systems are unstable. Of course, I wouldn't expect you to
>understand the subtle difference.

Yes, your example is one of negative feedback which can be unstable.

I suspect that complicated systems with multiple feedbacks, some of
which are positive, can be stable as long as the net effect is a
negative feedback. With the climate system, there is so much dissipation
that the result is highly damped and a slight increase in one variable
with positive feedback will not cause the system to shift into a runaway
(explosive) condition.

That said, there are likely to be thresholds in the system which could lead to
bistable conditions, such as the THC, which is thought to have several stable
states. If an overall warming results in the crossing of a threshold, it may
not be possible to return the climate to it's previous state by removing the
forcing which caused the change of state, as there is the prospect of
"deadbands" associated with the threshold type nonlinearity. The existance
of Ice Ages and Interglacials confirms that there are at least 2 stable states
for the climate system and there is the possibility of others.

--
Eric Swanson --- E-mail address: e_swanson(at)skybest.com :-)
--------------------------------------------------------------

David Ball

unread,
Jun 19, 2004, 11:24:21 AM6/19/04
to
On Sat, 19 Jun 2004 10:28:37 -0400, Steve Schulin
<steve....@nuclear.com> wrote:
Nothing of significance. As such, it was deleted. Perfesser,
any time you want to get down and dirty and discuss the science just
say the word. Of course, that will require you to understand the
basics, be open to other viewpoints and admit when you are wrong,
three things that you don't seem to have the ability to do.
BTW, have you figured out how something that doesn't change,
wobbles?

Steve Schulin

unread,
Jun 19, 2004, 1:21:10 PM6/19/04
to
In article <fhm8d0d9389q61uvi...@4ax.com>,
David Ball <wra...@mb.sympatico.ca> wrote:

In fact, the part you snipped was an illustration of how you, though
unwavering in your deceit, wobble on the application of tactics over
time.

charliew2

unread,
Jun 19, 2004, 2:13:25 PM6/19/04
to

I agree 100%. The T^4 effect guarantees that the GHG "problem" is
inherently stable.


charliew2

unread,
Jun 19, 2004, 2:14:25 PM6/19/04
to
James Annan wrote:
> charliew2 wrote:
>
>> I have to conclude that my definition of positive feedback is
>> different than yours.
>
> And, surprise surprise, yours is bogus, incomplete, or plain wrong, or
> some combination of all three.
>
> Which is pretty much par for the course for your "contributions" to
> this newsgroup.
>
> James

I'm not surprised by your comments, James. People like you don't know the
difference between a positive process gain and positive feedback.


charliew2

unread,
Jun 19, 2004, 2:19:01 PM6/19/04
to

The answer is that "k" in your equation is equivalent to a positive process
gain, not positive feedback.

Or you could think about the cruise control example before responding. A
cruise control with positive feedback can never hold a desired speed
setpoint.

>
> Or I could work through a more complex example.
>
>
>> I have to conclude that my definition of positive feedback is
>> different than yours.
>
> If so, then your definition doesn't match your observations about
> water vapor.

That's correct, it doesn't.

(cut)

David Ball

unread,
Jun 19, 2004, 2:27:15 PM6/19/04
to
On Sat, 19 Jun 2004 13:21:10 -0400, Steve Schulin
<steve....@nuclear.com> wrote:

>In article <fhm8d0d9389q61uvi...@4ax.com>,
> David Ball <wra...@mb.sympatico.ca> wrote:
>
>> On Sat, 19 Jun 2004 10:28:37 -0400, Steve Schulin
>> <steve....@nuclear.com> wrote:
>> Nothing of significance. As such, it was deleted. Perfesser,
>> any time you want to get down and dirty and discuss the science just
>> say the word. Of course, that will require you to understand the
>> basics, be open to other viewpoints and admit when you are wrong,
>> three things that you don't seem to have the ability to do.
>> BTW, have you figured out how something that doesn't change,
>> wobbles?
>
>In fact, the part you snipped was an illustration of how you, though
>unwavering in your deceit, wobble on the application of tactics over
>time.
>
>Very truly,
>

Why do you end your posts with this? You couldn't tell the
truth if your life depended on it.

Thomas Palm

unread,
Jun 19, 2004, 2:59:14 PM6/19/04
to
"charliew2" <char...@ev1.net> wrote in
news:10d90l3...@corp.supernews.com:

> Thomas Palm wrote:
>> As for the feedback, what you fail to take into account in your fear
>> about a runaway greenhouse effect is the stabilizing effect of the
>> T^4 dependence on thermal radiation from Earth, which provides a
>> strong negative feedback. That way you can have positive feedback
>> from water wapor and still not have a runaway effect.
>
> I agree 100%. The T^4 effect guarantees that the GHG "problem" is
> inherently stable.

Why the quotation marks around "problem"? Can't you just for once discuss
an issue in a scientific manner without trying to drop hints that we really
shouldn't worry? Why did you even bring up the possibility of a runaway
effect if you don't believe in it and no one else had mentioned it?

The situation isn't inherently stable, though. Given a sufficiently strong
positive feedback there will be a runaway effect. Fortunately we don't seem
to be close to any such point at the moment, but there is nothing
inherently impossible that it could happen. It did, after all, happen on
Venus.

Phil Hays

unread,
Jun 19, 2004, 3:55:09 PM6/19/04
to

The process gain is unity. If the feedback term "k" is zero, then the
output X follows the input Y with a gain of one, and with a time
delay. I'm sure an experienced controls engineer could write a
similar equation with a non-unity process gain.


>>>> I'll start by giving a few free hints:
>>>>
>>>> k < -1 is unstable. Try -1.1 and find out.
>>>>
>>>> k = .1 is quite stable. Try it and find out. This is a simple
>>>> example that anyone that can add and multiply can verify for
>>>> themselves that positive feedback does not meen runaway.
>>
>> Did you verify that positive k was stable, at least for k = .1?

Well, did you?


>>> How about I buy you a clue from a simple, real world (not college
>>> textbook, oversimplified) example? Let's say that you have a cruise
>>> control on your car. You speed up to the desired speed, and press
>>> the button to engage the speed control. When the speed drops below
>>> the setpoint, the controller lets up on the accelerator pedal, and
>>> when you go faster than desired, the controller pushes down on the
>>> accelerator pedal. In this instance, the controller acts such that
>>> it adds to the deviation from setpoint, which is a classic example
>>> of positive feedback.
>>
>> I could again ask you to treat this as an engineering problem. Give
>> your definitions. Write the equations. But would you do that? Could
>> you do that?
>>
>> Or I could write about any of several well known systems that use
>> positive feedback, like a regenerative radio receiver.
>>
>> Or I could point out that this "cruise control" example of yours could
>> be the same as my simple example if the controller was discrete time
>> and was slow enough. In other words, the "cruise control" would take
>> a speed measurement once every n seconds, then set the accelerator
>> based on that measurement, where n is large enough to have the car to
>> have responded to the change in throttle.
>
>Or you could think about the cruise control example before responding. A
>cruise control with positive feedback can never hold a desired speed
>setpoint.

Yes, Charlie, but that doesn't mean that it is not stable or will
"runaway", which is what you were claiming. All implementable
feedback systems will have an error between the desired and actual
output. It is true that your "cruise control" with positive feedback
will have a larger steady state error ("DC") than a "cruise control"
that just sets the throttle to a fixed value. It might, however, have
less dynamic error ("AC"), because it might be more stable. Showing
this requires some more involved math, or a computer model of a
system, or an experiment with the right real system.


>> Or I could work through a more complex example.
>>
>>
>>> I have to conclude that my definition of positive feedback is
>>> different than yours.
>>
>> If so, then your definition doesn't match your observations about
>> water vapor.
>
>That's correct, it doesn't.

Care to explain?

Phil Hays

unread,
Jun 19, 2004, 4:12:01 PM6/19/04
to
"charliew2" <char...@ev1.net> wrote:

If the process gain was zero, what would the output be?

If the feedback was zero, what would the output be?

Does that shoe leather taste nice?

charliew2

unread,
Jun 19, 2004, 6:35:04 PM6/19/04
to
Phil Hays wrote:
> "charliew2" <char...@ev1.net> wrote:
>
>> James Annan wrote:
>>> charliew2 wrote:
>>>
>>>> I have to conclude that my definition of positive feedback is
>>>> different than yours.
>>>
>>> And, surprise surprise, yours is bogus, incomplete, or plain wrong,
>>> or some combination of all three.
>>>
>>> Which is pretty much par for the course for your "contributions" to
>>> this newsgroup.
>>>
>>> James
>>
>> I'm not surprised by your comments, James. People like you don't
>> know the difference between a positive process gain and positive
>> feedback.
>
> If the process gain was zero, what would the output be?

If the process gain is zero, the output would be zero, as process gain is
the ratio of output over input.

>
> If the feedback was zero, what would the output be?

That depends on what the input is, and what the transfer function is.

>
> Does that shoe leather taste nice?

You know, Phil, it is becoming obvious to me that the jargon used by most
members of this NG is distinctly different than expected. In addition,
since there are at least 50 years of established process control theory and
jargon, it would be nice if you considered that adoption of an established
jargon would be beneficial to furthering your global-warming/climate-change
goals of educating the public (if you have such goals). If anyone in the
future ever starts thinking about process control of global mean
temperature, the conflict between your choice of jargon and the process
control community is going to make it very difficult for you and the process
control guys to understand each other.

Just a suggestion.


Michael Tobis

unread,
Jun 19, 2004, 6:38:48 PM6/19/04
to
Well, this one had me stumped at first, but fortunately "with enough
eyeballs, all bugs are shallow".

There's a remarkable discussion on
http://www.ukweatherworld.co.uk/forum/thread-view.asp?threadid=6723&start=16&posts=24

The short answer to the quandary that Schulin presents us with is that
this result is just a recycling of the suspect Spencer and Christy MSU
data again.

Yes, it's an outlier, but its the same old outlier, which is why
nobody outside the "what-me-worry" press has taken any note of it.
This paper has not really changed anybody's thinking about the
istuation. It's the same old story in a new bookjacket.

There are, after all, strong reasons to believe that the
Spencer/Christy trend is an instrument artifact, not a real
observation. Several other interpretations of the same MSU data show a
warming trend.

Let me quote from the referenced website:

=== begin quote

When looking at statistics you have to look carefully at the
assumptions and background. For example, we know that the climate has
long-term anti-persistency, since otherwise we would end up with a
runaway greenhouse effect. The antipersistency of the climate is not
in contradiction with the IPCC - in fact, models are rather too
antipersistent (they're good at predicting stable climates, not good
at predicting rapid change). In fact, this paper
( dead link to http://ory.ph.biu.ac.il/~havlin/PS/gvbbhs419.pdf )
complains that the models "the models underestimate the long-range
persistence of the atmosphere"

[Persistency, for those who don't know and are reading this, can be
described very basically as a measure of how recent increases effect
future increases. So, if temperature has been going up recently, and
that makes it more likely that it will go up in the future, then it's
persistent.)

Secondly, the Karner paper uses the MSU2 data of Christy et al. We
already know that something is going on in this dataset that is not
compatible with the model predictions. Karner shows that these data
show antipersistency - as might be expected from the observation that
the trend is flat. If CO2 is rising, yet the troposphere is not
warming, then you would expect that there must be a negative feedback
in operation - what Karner has done is to demonstrate the
statistically.

Thirdly, he uses the solar data of Frohlich & Lean. Notably, this is
the dataset that finds no increase in solar brightness over the past
20 years. i.e. it is incompatible with sceptic arguments. Karner finds
that he persistency of this dataset is similar to that of MSU2.

What are we to make of all this? Well, firstly, when something
perturbs the troposphere something acts to return it to normal. This
could, for example, result from el nino followed by la nina (which is
probably the dominant annual-scale fluctuation in the troposphere.
Cooling caused by Pinatubo was followed by warming as the effects wore
off. Etc. There is, however, some persistency (since H>0).

The persistency is similar to the solar persistency. This is hard to
interpret. What it doesn't mean is that there is any correlation
between solar and MSU2 (there clearly isn't). It means that the sun's
output has a similar tendency to return to normal as MSU2. Maybe it's
just coincidence. Maybe there is some complex reason for this - but
Karner doesn't speculate!

===

end quote

Thanks to Tom Rees of Brighton UK for this very helpful analysis.

Let me say that I'm amazed that JGR let such a strong statement about
IPCC into the final article. I think Karner was out of line for
drawing such a strong conclusion from a single, controversial data
set.

mt

Steve Schulin <steve....@nuclear.com> wrote in message news:<steve.schulin-A7E...@comcast.dca.giganews.com>...


> In article <bcaf804.04061...@posting.google.com>,
> m...@3planes.com (Michael Tobis) wrote:
>
> > It's about twenty years too late to be arguing on this point. Not that
> > that would stop anyone. (sigh)
>

Phil Hays

unread,
Jun 19, 2004, 7:17:27 PM6/19/04
to
"charliew2" <char...@ev1.net> wrote:
>Phil Hays wrote:
>> "charliew2" <char...@ev1.net> wrote:
>>> I'm not surprised by your comments, James. People like you don't
>>> know the difference between a positive process gain and positive
>>> feedback.
>>
>> If the process gain was zero, what would the output be?
>
>If the process gain is zero, the output would be zero, as process gain is
>the ratio of output over input.

PH> X(t+1) := k*X(t) + Y(t)

PH> This is a first order discrete time system. If k is negative, the
PH> feedback is negative. If k is positive, the feedback is positive.
PH> What range of k is stable?

CW> The answer is that "k" in your equation is equivalent to
CW> a positive process gain, not positive feedback.

So if k is zero:

X(t+1) := Y(t)

or the output is equal to the input after a unit time delay.


>> If the feedback was zero, what would the output be?
>
>That depends on what the input is, and what the transfer function is.

Exactly.

X(t+1) := k*X(t) + Y(t)

"k" is the feedback term. Right?

So again, over what range of k is the system stable?


>> Does that shoe leather taste nice?

>You know, Phil, it is becoming obvious to me that the jargon used by most
>members of this NG is distinctly different than expected. In addition,
>since there are at least 50 years of established process control theory

Can we agree on definations from _Modern Control Engineering_ by
Ogata:

http://www.amazon.com/exec/obidos/search-handle-form/104-5888570-7249527


and
>jargon, it would be nice if you considered that adoption of an established
>jargon would be beneficial to furthering your global-warming/climate-change
>goals of educating the public (if you have such goals). If anyone in the
>future ever starts thinking about process control of global mean
>temperature, the conflict between your choice of jargon and the process
>control community is going to make it very difficult for you and the process
>control guys to understand each other.
>
>Just a suggestion.
>

charliew2

unread,
Jun 19, 2004, 7:18:54 PM6/19/04
to

OK, Phil. You be the controller, and act like the controller I talked
about. If the speed drops below your desired value, let up on the
accelerator pedal. If the speed goes above your desired value, push down on
the accelerator pedal. Also, the size of your "move" must be proportional
to the error. Try it, and get back to me.

> All implementable
> feedback systems will have an error between the desired and actual
> output.

That is why there is an integral term in a PI controller - to eliminate
offset relative to setpoint.

> It is true that your "cruise control" with positive feedback
> will have a larger steady state error ("DC") than a "cruise control"
> that just sets the throttle to a fixed value. It might, however, have
> less dynamic error ("AC"), because it might be more stable. Showing
> this requires some more involved math, or a computer model of a
> system, or an experiment with the right real system.
>

Gee, Phil, you really don't have a clue, do you? I suspect that all of your
process control experience is from a textbook, and none of it is from the
real world.

(cut)

I'm not going to argue the fine points with you anymore Phil. If you really
believe what you say, there's nothing I can say that will convince you.

Phil Hays

unread,
Jun 19, 2004, 7:56:36 PM6/19/04
to

Well, can you? Do you agree that the feedback term "k" can be
positive and the resulting system be stable? Could you write a
similar equation with a non-unity process gain?


>>>>>> I'll start by giving a few free hints:
>>>>>>
>>>>>> k < -1 is unstable. Try -1.1 and find out.
>>>>>>
>>>>>> k = .1 is quite stable. Try it and find out. This is a simple
>>>>>> example that anyone that can add and multiply can verify for
>>>>>> themselves that positive feedback does not meen runaway.
>>>>
>>>> Did you verify that positive k was stable, at least for k = .1?
>>
>> Well, did you?

Well, did you verify this?


>> All implementable
>> feedback systems will have an error between the desired and actual
>> output.
>
>That is why there is an integral term in a PI controller - to eliminate
>offset relative to setpoint.

The integral term eliminates DC offset, however, there will still be a
dynamic or AC error.


>Gee, Phil, you really don't have a clue, do you?

Oh, let me check.... Yes, I just got a fresh shipment in. How many do
you want to buy? I also have a good supply of hints, always just
fifty cents for a good customer like you.


>I'm not going to argue the fine points with you anymore Phil. If you really
>believe what you say, there's nothing I can say that will convince you.

Fine points? That's a joke, for this is such a simple and basic
example, none of them hard to understand or subtle. Just find the
range of k where the following equation is stable:

X(t+1) := k*X(t) + Y(t)

No fine point there, no sir. Just some basic math, well within anyone
with a high school education.

charliew2

unread,
Jun 19, 2004, 8:02:12 PM6/19/04
to
Phil Hays wrote:
> "charliew2" <char...@ev1.net> wrote:
>> Phil Hays wrote:
>>> "charliew2" <char...@ev1.net> wrote:
>>>> I'm not surprised by your comments, James. People like you don't
>>>> know the difference between a positive process gain and positive
>>>> feedback.
>>>
>>> If the process gain was zero, what would the output be?
>>
>> If the process gain is zero, the output would be zero, as process
>> gain is the ratio of output over input.
>
>> X(t+1) := k*X(t) + Y(t)
>
>> This is a first order discrete time system. If k is negative, the
>> feedback is negative. If k is positive, the feedback is positive.
>> What range of k is stable?
>
>> The answer is that "k" in your equation is equivalent to
>> a positive process gain, not positive feedback.
>
> So if k is zero:
>
> X(t+1) := Y(t)
>
> or the output is equal to the input after a unit time delay.
>
>
>>> If the feedback was zero, what would the output be?
>>
>> That depends on what the input is, and what the transfer function is.
>
> Exactly.
>
> X(t+1) := k*X(t) + Y(t)
>
> "k" is the feedback term. Right?
>
> So again, over what range of k is the system stable?
>
>
>>> Does that shoe leather taste nice?
>
>> You know, Phil, it is becoming obvious to me that the jargon used by
>> most members of this NG is distinctly different than expected. In
>> addition, since there are at least 50 years of established process
>> control theory
>
> Can we agree on definations from _Modern Control Engineering_ by
> Ogata:
>
> http://www.amazon.com/exec/obidos/search-handle-form/104-5888570-7249527

I'll have a look and let you know. My books are by Deshpande and Ash, and
Stephanopoulos, and they don't seem to use the same nomenclature that your
refrence does.

(cut)

charliew2

unread,
Jun 19, 2004, 8:31:45 PM6/19/04
to
Phil Hays wrote:
> "charliew2" <char...@ev1.net> wrote:
(cut)

>
> Can we agree on definations from _Modern Control Engineering_ by
> Ogata:
>
> http://www.amazon.com/exec/obidos/search-handle-form/104-5888570-7249527

Phil, I found the book at Amazon, but I don't intend to buy it just to look
up the definitions. However, a search through Google for "positive
feedback", and a search within results for "control systems", gave me
results which listed at least two different definitions of positive
feedback. All along, I had assumed that there was just one commonly
accepted definition. Obviously, this isn't true. Please post your
definition (from Ogata). Thanks.

Steve Schulin

unread,
Jun 20, 2004, 12:00:17 AM6/20/04
to

This quote about models underestimating long-range persistence is from
Govindan et al ["Global Climate Models Violate Scaling of the Observed
Atmospheric Variability", Physical Review Letters 89:28501, 8 July
2002]. The long range to which it explicitly refers is on the scale of
ten years. Karner, however, explicitly refers to periods as short as two
months.

BTW, the full quote from Govindan et al is "Since the models
underestimate the long-range persistence of the atmosphere and
overestimate the trends, our analysis suggests that the anticipated
global warming is also overestimated by the models." That is their final
sentence in the paper, before the Thank yous and endnotes.

>
> [Persistency, for those who don't know and are reading this, can be
> described very basically as a measure of how recent increases effect
> future increases. So, if temperature has been going up recently, and
> that makes it more likely that it will go up in the future, then it's
> persistent.)
>
> Secondly, the Karner paper uses the MSU2 data of Christy et al. We
> already know that something is going on in this dataset that is not
> compatible with the model predictions. Karner shows that these data
> show antipersistency - as might be expected from the observation that
> the trend is flat. If CO2 is rising, yet the troposphere is not
> warming, then you would expect that there must be a negative feedback
> in operation - what Karner has done is to demonstrate the
> statistically.

The use of MSU data seems quite reasonably explained in this case. He
chose it not for climatic importance per se, but for its methodical
character, he says. Karner discusses Hurrell et al's comparison of MSU
with gridded sonde data [BAMS 81:2165]. The relevance of criticisms (of
Spencer and Christy's decadal trends) to the daily time series' analysis
by Karner is not as clear as the commenter suggests.

>
> Thirdly, he uses the solar data of Frohlich & Lean. Notably, this is
> the dataset that finds no increase in solar brightness over the past
> 20 years. i.e. it is incompatible with sceptic arguments. Karner finds
> that he persistency of this dataset is similar to that of MSU2.

Willson and Mordvinov's "Secular Total Solar Irradiance trend during
solar cycles 21-23" [Geophysical Research Letters 30(5):1199
doi:10.1029/2002GL016038, 2003] explains why Frohlich & Lean failed in
long term trending. It's not at all clear that the type of degradation
they describe would make a difference in the persistency findings of
Karner.

> What are we to make of all this? Well, firstly, when something

> perturbs the troposphere something acts to return it to normal. ...

This sounds like a statement of dominant negative feedback to me.

> ... This


> could, for example, result from el nino followed by la nina (which is

> probably the dominant annual-scale fluctuation in the troposphere. ...

Well, this seems rather underwhelming as an explanation for two-month
timescale cited by Karner.

> Cooling caused by Pinatubo was followed by warming as the effects wore
> off. Etc. There is, however, some persistency (since H>0).

Good point, albeit quite a small part of the record.

>
> The persistency is similar to the solar persistency. This is hard to
> interpret. What it doesn't mean is that there is any correlation

> between solar and MSU2 (there clearly isn't). ...

Karner's Fig. 4 shows a striking correlation, contrary to this comment.
Paragraph 50 concludes "Variability of the solar forcing is quite
accurately followed by tropospheric temperature anomaly. This is an
indication that the solar forcing variability is actually the governing
one among other existing (random or not) forcings in the Earth climate
system."

>... It means that the sun's


> output has a similar tendency to return to normal as MSU2. Maybe it's
> just coincidence. Maybe there is some complex reason for this - but
> Karner doesn't speculate!

What speculation is needed to see that the dominance of positive
feedback, embraced by IPCC, and previously espoused as a settled matter
by you, is flatly contradicted by the statistically significant (at p >
.95) data?

>
> ===
>
> end quote
>
> Thanks to Tom Rees of Brighton UK for this very helpful analysis.
>
> Let me say that I'm amazed that JGR let such a strong statement about
> IPCC into the final article. I think Karner was out of line for
> drawing such a strong conclusion from a single, controversial data
> set.
>
> mt

Other than voicing strong opinions, you don't give any hint that you
actually read the Karner paper before endorsing Dr. Rees' comments. I'm
curious whether you read this Karner paper before expressing opinion
that he was out of line.

>
> Steve Schulin <steve....@nuclear.com> wrote in message
> news:<steve.schulin-A7E...@comcast.dca.giganews.com>...
> > In article <bcaf804.04061...@posting.google.com>,
> > m...@3planes.com (Michael Tobis) wrote:
> >
> > > It's about twenty years too late to be arguing on this point. Not that
> > > that would stop anyone. (sigh)
> >
> > Fortunately, we have the last about 20 years experience to help
> > understand. Karner [J. Geophys. Res., 10.1029/2001JD002024, 2002]
> > concludes that negative feedback has dominated the climate system during
> > 1979-2001.

Very truly,

Steve Schulin
http://www.nuclear.com

Phil Hays

unread,
Jun 20, 2004, 12:52:23 AM6/20/04
to
"charliew2" <char...@ev1.net> wrote:
>Phil Hays wrote:
>> "charliew2" <char...@ev1.net> wrote:
>(cut)
>>
>> Can we agree on definations from _Modern Control Engineering_ by
>> Ogata:
>>
>> http://www.amazon.com/exec/obidos/search-handle-form/104-5888570-7249527
>
>Phil, I found the book at Amazon, but I don't intend to buy it just to look
>up the definitions. However, a search through Google for "positive
>feedback", and a search within results for "control systems", gave me
>results which listed at least two different definitions of positive
>feedback. All along, I had assumed that there was just one commonly
>accepted definition.

X(t+1) := k*X(t) + Y(t)

This is a first order discrete time system. If k is negative, the


feedback is negative. If k is positive, the feedback is positive.

What range of k is the system stable?

A very simple problem. Can't you solve it?

FerdiEgb

unread,
Jun 20, 2004, 6:33:05 AM6/20/04
to
"charliew2" <char...@ev1.net> wrote in message news:<10d9mrh...@corp.supernews.com>...

Charlie,

If there is a reaction of any system on an initial disturbance, then
this can be positive or negative. If the result of the reaction is not
going back to the original disturbed parameter ("open loop"), then it
is not of interest (in the case of climate), but may be used
"feedforward" to adjust other parameters to counter the effect (which
is used in many cases in the process industry). If the reaction
influences the disturbed parameter directly ("closed loop", see
http://www.tpub.com/content/doe/h1013v2/css/h1013v2_113.htm), then
this is a "feedback". That can be positive or negative too, depending
on the amplification factor of your equation. As long as this factor
is between -1 (negative feedback) and +1 (positive feedback) then the
total system remains stable.

To give an example, if the feedback amplification factor is as high as
0.5, then the values at different times, beginning at the original
disturbance looks like:

Initial disturbance: Y(t) = 1 °C
Feedback factor k = 0.5

X(t+1) := k*X(t) + Y(t)

X(t+1) = 0.5 °C + 1 °C = 1.5 °C

X(t+2) = 0.75 °C + 1 °C = 1.75 °C

X(t+3) = 0.875 °C + 1 °C = 1.875 °C

etc...

At last, in infinitum, the initial disturbance in temperature doubled
with a feedback amplification factor of 0.5. But this still is stable.

The point is, what is the real amplification factor for water vapour
from an initial disturbance (either solar or GHG induced)? According
to a geologist (see:
http://members.lycos.nl/ErrenWijlens/family/CVHE2001.htm):

"The water vapour feedback by Arrhenius is only a factor 1.3. This was
explained by him in 1901 and confirmed by Ramanatan and Vogelmann in
1997. Taking 3.7 W/m2 for CO2 doubling and the Stefan-Boltzmann
equation gives us 0.6833 degrees warming (Erren, 2002).
Including the water feedback gives 0.6833*1.3= 0.888 K Wich fits
beautifully in Douglas Hoyt's empirical range of 0.5 - 0.9 K for CO2
doubling."

Note that the factor 1.3 is the end result, not the amplification
factor, which is much smaller.

This doesn't include other feedbacks like cloud formation. In the
tropics (halve of the earth's surface), cloud formation and/or faster
circulation gives a negative feedback, some 2 W/m2 for an increase of
0.1 °C in SST, and some 7 W/m2 during an El Niño event. See:
http://www.atmos.ucla.edu/csrl/publications/pub_exchange/Wielicki_et_al_2002.pdf
(fig. 2). This is not included in the current climate models. Compare
that to the some 4 W/m2 that a CO2 doubling should induce.

Pre-industrial changes in CO2 levels seem to have no measurable
influence on temperature in a 50 ppmv range, see:
http://www.ping.be/~ping5859/co2_temp_ice.html and as you can see, CO2
follows temperature changes, doesn't induce them...

Ferdinand

Steve Schulin

unread,
Jun 20, 2004, 9:12:30 AM6/20/04
to
In article <bb19d0p8ll8mqr42b...@4ax.com>,
David Ball <wra...@mb.sympatico.ca> wrote:

> <steve....@nuclear.com> wrote:


> > David Ball <wra...@mb.sympatico.ca> wrote:
> >> <steve....@nuclear.com> wrote:
> >> Nothing of significance. As such, it was deleted. Perfesser,
> >> any time you want to get down and dirty and discuss the science just
> >> say the word. Of course, that will require you to understand the
> >> basics, be open to other viewpoints and admit when you are wrong,
> >> three things that you don't seem to have the ability to do.
> >> BTW, have you figured out how something that doesn't change,
> >> wobbles?
> >
> >In fact, the part you snipped was an illustration of how you, though
> >unwavering in your deceit, wobble on the application of tactics over
> >time.
> >
> >Very truly,
> >
> Why do you end your posts with this? You couldn't tell the
> truth if your life depended on it.

Happy Father's Day, Mr. Ball, to you and all the other Dads here.
Despite our differences of opinion, there's surely some common
sentiments amongst us that can be shared without rancor. One is the
virtually universal love parents have for their children, and the
corresponding desire to make the world a better place for them and
theirs.

Sincerely,

Steve Schulin

charliew2

unread,
Jun 20, 2004, 12:50:29 PM6/20/04
to
Phil Hays wrote:
> "charliew2" <char...@ev1.net> wrote:
>> Phil Hays wrote:
>>> "charliew2" <char...@ev1.net> wrote:
>> (cut)
>>>
>>> Can we agree on definations from _Modern Control Engineering_ by
>>> Ogata:
>>>
>>> http://www.amazon.com/exec/obidos/search-handle-form/104-5888570-7249527
>>
>> Phil, I found the book at Amazon, but I don't intend to buy it just
>> to look up the definitions. However, a search through Google for
>> "positive feedback", and a search within results for "control
>> systems", gave me results which listed at least two different
>> definitions of positive feedback. All along, I had assumed that
>> there was just one commonly accepted definition.
>
> X(t+1) := k*X(t) + Y(t)
>
> This is a first order discrete time system. If k is negative, the
> feedback is negative. If k is positive, the feedback is positive.
> What range of k is the system stable?
>
> A very simple problem. Can't you solve it?

Your nomenclature is different than what I have in my textbooks. However,
I'll take a guess. It looks to me like the system is stable for absolute
value of k less than 1.


charliew2

unread,
Jun 20, 2004, 12:55:19 PM6/20/04
to

I agree. Happy Father's day to all.


Psalm 110

unread,
Jun 20, 2004, 4:02:12 PM6/20/04
to
Steve Schulin <steve....@nuclear.com> wrote in message news:<steve.schulin-598...@comcast.dca.giganews.com>...

>
> Happy Father's Day, Mr. Ball, to you and all the other Dads here.
> Despite our differences of opinion, there's surely some common
> sentiments amongst us that can be shared without rancor. One is the
> virtually universal love parents have for their children, and the
> corresponding desire to make the world a better place for them and
> theirs.

> Steve Schulin

What a cheap ploy from a GLOBAL WARMING baby-killer -- yes there are
dad's who are sociopaths, who kill all their children and their wife,
then themselves. There are guys going to prison for child abuse every
day of the year.

People who love their children OBEY the Precautionary Principle, and
do not gamble with their children's environment.

AFTER you have demonstrated responsibility to the next generation, MR.
nuclear.com, BY DISPOSING THE ACCUMULATED NUCLEAR WASTES WE ALREADY
HAVE BACKED UP, then you may be considered a FORMER-sociopath.

Meanwhile you promote the position of paid liars from the Pollution
and Poison Industry, as if they were credible instead of proven
corrupt, and you have not yet evaluated the evidence which withstood
due process of law once in courtrooms already and found to be
incriminatting evidence of conspiracy.

http://sciencecop.joeuser.com/index.asp?c=1

http://sciencecop.joeuser.com/bloglist.asp

http://sciencecop.joeuser.com/index.asp?AID=18766


In 1993-1994 AdTI assembled a team of the most corrupt people working
in science to obscure the health hazards of smoking and second-hand
smoke from cigarettes. Many of the AdTI team players are still active
to this very day taking huge payments from various dirty industries to
confuse issues and smear the reputations of their opposition. Records
preserved after the great multi-billion-dollar lost federal lawsuit
cases by the tobacco industry are now online exposing the dirty tricks
played in secrecy back then. A network of science-villians was forged
by big-tobacco, and assembled by AdTI into a permanent cancer on
society. AdTI drove the getaway car for corporate serial murderers.

Alexis de Tocqueville Institution, which has often been little more
than a post office box and some fly-by-night rented offices, forever
lost its credibility, forever lost its right to participate in
American dialog, by devoting itself to intentional fraudulent
subversion of the American people.


http://tobaccodocuments.org/ti/TI31749097-9099.html
"Issue Report Environmental Protection Agency's Science", Date: 25 Sep
1993, Length: 3 pages By Jonathan Tolman and Cesar Conda. (Cesar V.
Conda was Alexis de Tocqueville Institution's Executive Director;
Jonathan Tolman was visting fellow of Alexis de Tocqueville
Institution -- this is an AdTI report.)

http://tobaccodocuments.org/lor/92756102-6120.html
"the Epa and the Science of Environmental Tobacco Smoke", Date: 1994
Length: 19 pages (draft of pre-publication report found in Lorillard
Tobacco Company files)
by Dr. S. Fred Singer, Professor of Environmental Sciences (on leave),
University of Virginia, and Senior Fellow Alexis de Tocqueville
Institution, and Mr. Kent Jeffreys, Adjunct Scholar Alexis de
Tocqueville Institution.

http://tobaccodocuments.org/lor/92756807-6876.html
"Science, Economics, and Environmental Policy: A Critical Examination
A Research Report Conducted by the Alexis De Tocqueville Institution"
Date: 11 Aug 1994, Length: 70 pages

Academic Advisory Board -- Dr. Gary Anderson, Professor of Economics,
California State University-Northridge -- Dr. Nancy Bord (Yonge),
Visiting Scholar, The Hoover Institution, Stanford University -- Dr.
Gordon L. Brady, Associate Professor and Director Environmental
Studies, Sweet Briar College -- Dr. Jeffrey Clark, Professor of
Economics, University of Tennessee-Chattanooga -- Dr. Michael Darby,
Professor of Economics, and Director John M. Olin Center for Policy,
University of California, Los Angeles -- Dr. Robert Ekelund, Lowder
Eminent Scholar, Auburn University -- Dr. Michael Gough, Project
Director, Congressional Office of Technology Assessment -- Dr. William
Hazeltine, Environmental Consultant -- Dr. Thomas Hopkins, Gosnell
Professor of Economics, Rochester Institute of Technology -- Dr.
Dwight R. Lee, Ramsey Professor of Economics, University of Georgia --
Dr. Michael Marlow, Professor of Economics, California State
Polytechnic University-San Luis Obispo -- Dr. Thomas Gale Moore,
Senior Fellow The Hoover Institution, Stanford University -- Dr.
Malcolm Ross, Research Mineralogist U.S. Geological Survey -- Dr. S.
Fred Singer Professor Emeritus of Environmental Sciences, University
of Virginia and President Science and Environmental Policy Project
(SEPP) -- Dr. Gerhard Stohrer, Director of Chemical Risk Program,
Science and Environmental Policy Project, and former Department Head
Sloan-Kettering Institute for Cancer Research -- Dr. Mark Thornton,
Professor of Economics Auburn University -- Dr. Robert D. Tollison,
Duncan Black Professor of Economics and Director Center for the Study
of Public Choice, George Mason University -- Dr. Richard Vedder,
Professor of Economics, University of Ohio -- Dr. Richard Wagner,
Professor of Economics and Chairman, Department of Economics, George
Mason University

Author: Kent Jeffreys,
Principal Reviewer: Dr. S. Fred Singer,
Senior Staff and Contributing Associates:
Rachael Applegate, Bruce Bartlett, Merrick Carey, Cesar Conda, Gregory
Fossedal, Dave Juday, Felix Rouse, Aaron Stevens.

http://tobaccodocuments.org/ti/TIMN0339276-9278.html
Tobacco Institute "Communications Efforts September 1988", Date: Sep
1988, Length: 3 pages
Media Tours by Consultants
-- "Social Cost" media tours by George Mason University economists
Robert Tollison and Richard Wagner were launched in September in
Richmond, VA and Tulsa, OK. These tours discuss the Tollison/Wagner.
book, Smoking and the State, and the issues surrounding the misuse of
"social costs." Enclosed you will find the press kit used with the
media and reports on the press generated by the tour.

Robert Tollison and Richard Wagner were corrupt on the day they sat in
on the "impartial peer-review" of "Science, Economics, and
Environmental Policy: A Critical Examination, A Research Report
Conducted by the Alexis De Tocqueville Institution"

http://tobaccodocuments.org/pm/2501254705-4708.html
Proposal for the Organisation of the Whitecoat Project, Date: 22 Feb
1988 (est.), Length: 4 pages

SUMMARY OF THE WHITECOAT PROJECT
The Project is designed to support market-level ETS programmes within
the PM EEMA and EEC markets. The Objectives of these overall ETS
programmes are defined as:-
End Goals:
- Resist and roll back smoking restrictions.
- Restore smoker confidence.
Pre-requisites:
- Reverse scientific and popular misconception that ETS is harmful.
- Restore social acceptability of smoking.

http://tobaccodocuments.org/landman/2023856052-6057.html
The ETS Program for 1991, Date: 1990 (est.), Length: 6 pages

"Science Objectives" were estimated to cost a whopping $16,688,400 and
included "Develop and support activities and research which maintain
the controversy..." about secondhand smoke and "Maintain research
activity...to provide support for our position."

Among the "Science Objectives" were "Develop[ing] and support[ing]
activities and research which maintain the controversy" about tobacco
smoke.

http://tobaccodocuments.org/ti/TIOK0003644.html
Date: 31 Jan 1989, Length: 1 page

Professional fees and expenses paid Dwight Lee and Robert Tollison
$8,421.37. Up to nearly a million dollars per year budget is shared by
a half-dozen "whitecoats" deception agents in Tobacco Institute
budgetary records of this time period.

http://tobaccodocuments.org/ti/TIFL0536080-6087.html

Robert D. Tollison received these check numbers:
page 6:
Cumulative General Ledger the Tobacco Institute Inc. Period Ending
09-30-87
* Robert D. Tollison Check #42538 87-MAR-30 $16,450
* Robert D. Tollison Check #44247 87-MAY-29 $14,075
page 7:
* Robert D. Tollison Check #45160 87-JUL-07 $27,388
* Robert D. Tollison Check #45717 87-JUL-22 $7,750 (Totals paid over 5
months = $65,663.)

Gary Anderson - Tobacco Industry stealth consultant 1988-1996 --
http://tobaccodocuments.org/ti/TIDN0018432-8476.html (Tobacco
Institute) -- http://tobaccodocuments.org/atc/71008079.html (American
Tobacco Company) -- http://tobaccodocuments.org/ti/TIOK0021837-1844.html
(Tobacco Institute) --
http://tobaccodocuments.org/lor/88116221-6224.html (Tobacco Institute)
-- http://tobaccodocuments.org/atc/71081376.html (American Tobacco
Company) -- http://tobaccodocuments.org/atc/71081377.html (American
Tobacco Company) -- http://tobaccodocuments.org/lor/86015105-5117.html
(Lorillard Tobacco Company) --
http://tobaccodocuments.org/lor/86015122-5123.html (Lorillard Tobacco
Company) -- http://tobaccodocuments.org/lor/92761030-1042.html
(Lorillard Tobacco Company) --
http://tobaccodocuments.org/ti/TIDN0006954-6958.html (Tobacco
Institute) -- http://tobaccodocuments.org/ti/TIDN0011871-1904.html
(Tobacco Institute) --
http://tobaccodocuments.org/ti/TIDN0005687-5689.html (Tobacco
Institute) -- http://tobaccodocuments.org/ti/TIFL0536332-6369.html
(Tobacco Institute) --
http://tobaccodocuments.org/ti/TIFL0536164-6203.html (Tobacco
Institute) -- http://tobaccodocuments.org/ti/TIFL0538126-8164.html
(Tobacco Institute) --
http://tobaccodocuments.org/ti/TIDN0017394-7432.html (Tobacco
Institute) -- http://tobaccodocuments.org/ti/TI16551799-1815.html The
Tobacco Institute -- http://tobaccodocuments.org/pm/2074211106.html
(Philip Morris) --

Another CORRUPT link in the Alexis de Tocqueville Institution chain of
frauds -- Gordon Macklin, who was director during WorldCom's
$9,000,000,000.00 stock-manipulations frauds. Macklin did NOTHING
while WorldCom was looted, and he has done NOTHING to stop the
Microsoft-benefits of fraulent Ken Brown-AdTI attacks on
community-created public-spirited software that allows citizens free
choice to escape the Microsoft monopoly on operating systems and
productivity softwares. Brown has been caught telling lies, and it is
Macklin's legal duty to retract Brown's statements, fire Brown, and
apologize to the injured public.

http://www.usatoday.com/money/industries/telecom/2003-06-10-worldcomboard_x.htm

...

http://www.ecosyn.us/adti/Singer-Nightline.html
http://www.ecosyn.us/adti/Stohrer-Singer.html
http://www.ecosyn.us/adti/ADTI_Frauds_01.html
http://www.ecosyn.us/adti/Pelosi.html
http://www.ecosyn.us/adti/Singer-1993-1994.html
http://www.ecosyn.us/adti/Singer-Seitz.html

Phil Hays

unread,
Jun 20, 2004, 9:55:31 PM6/20/04
to
"charliew2" <char...@ev1.net> wrote:
>Phil Hays wrote:

>> X(t+1) := k*X(t) + Y(t)
>>
>> This is a first order discrete time system. If k is negative, the
>> feedback is negative. If k is positive, the feedback is positive.
>> What range of k is the system stable?

>I'll take a guess. It looks to me like the system is stable for absolute


>value of k less than 1.

So then we agree that positive feedback does not imply a unstable
system?

David Ball

unread,
Jun 21, 2004, 7:41:26 AM6/21/04
to
On Fri, 18 Jun 2004 18:11:03 GMT, Thomas Palm
<Thoma...@chello.removethis.se> wrote:

>"Geoff" <gghi...@nospam.ca> wrote in news:cav2bo$4tg$1...@news.ucalgary.ca:
>
>> "Ian St. John" <ist...@noemail.ca> wrote in message
>
>>> http://www.radix.net/~bobg/climate/halpern.trap.html
>>> Table 2.2 Contributions of atmospheric ratiation absorbers
>>> to thermal trapping
>>>
>>> Species removed % trapped radiation remaining
>>> All 0
>>> H2O CO2 O3 50
>>> H2O 64
>>> Clouds 86
>>> CO2 88
>>> O3 97
>>> None 100
>>> Data from Rev. Geophys. & Space Sci. 16 (1978) 465
>>
>> Given this set of numbers what is the response to the argument that
>> since C02 is such a small fraction of the greenhouse gas potential
>> (from my reading O3 is about twice as efficient as H2O, CO2 about 35%
>> more efficient) and that there is nothing to do about water vapour
>> anyway, why spend so much time, effort and resources on something that


>> accounts for a very small percentage of the atmosphere's capacity to
>> create a greenhouse effect?
>
>That is a bogus argument created by people who just don't want to do
>anything about climate change, often because they are in the business of
>emitting CO2.

Look at it from the public's perspective, a public that can
only view it in the most simplistic terms: this is a very compelling
argument. It's wrong, but that doesn't matter. If your goal is to fool
a majority of a scientifically uneducated populace, this is exactly
the kind of argument you make.


Robert Grumbine

unread,
Jun 21, 2004, 9:16:27 AM6/21/04