@physicistdave...<blockquote>Geoff, a negative feedback does not give zero change: it just reduces the effect from what it otherwise would be — i.e., the multiplier is positive but less than 1.0.</blockquote><blockquote>The reason is simple to explain to anyone who understands control theory: indeed, anyone who understands control theory already knows the answer.</blockquote><blockquote>To try to explain it non-mathematically, well… if the total effect ended up being exactly zero, then there would be nothing there to continue driving the negative feedback. You need some non-zero residual effect to keep the negative feedback occurring and thereby continue to cancel out much of the initial effect.</blockquote>You're wrong. When it comes to climate change, “<i>feedbacks</i>” are a myth: <i>i.e.</i> a loose metaphor intended to incent some action or thought.
IIRC Richard Lindzen once told Congress that “<i>global average temperature</i>” doesn't actually do anything or have any effect. (OTOH I couldn't find it with a quick Google search, so perhaps my recollection is wrong.) But this makes the point. What matters is what the temperature <b>at each point</b> does, after whatever effect increased GHG's have <b>at that point.</b>
As a result, the effect of more CO2 could be represented in a change to the temperature field <b>at each point,</b> with a set of follow-on changes including increased evaporation, that could easily drive increased cloudiness and albedo at other points.*
What this means is that the "driving effect" of increased CO2 <b>excluding</b> any contribution from changes to evaporation and precipitation (as cloud droplets) of water could be summed/averaged to one number, say 1.2°C, while the "resulting effect" <b>including</b> those contributions could be a smaller number, such as 0.8°C, 0°C, or even some negative number such as -0.4°C.
This in turn means that any attempt to apply “<i>control theory</i>” is invalid. When you say “<i>if the total effect ended up being exactly zero,</i>” the total effect on the <b>entire temperature field</b> would be present, and continue to have follow-on effects, but the <b>average</b> isn't something that can be used in any good mathematical analogy using “<i>control theory</i>”.
It could easily end up “<i>being exactly zero</i>”, although as I said above it would be very unlikely. To the extent that “<i>ECS</i>” (or “<i>TCR</i>”) actually exist as invariant numbers, a PFD for the value should have a tail that extends past zero. IMO a small tail, but real.
This is why things like “<i>feedbacks</i>” (and “<i>forcings</i>”) are myths, a point that must always be kept in mind when considering subjects like climate change. If the overall effect can be <b>proven</b> by observations to work in a way that could be described by “<i>control theory</i>”, then it can be used as an <b>explanatory analogy</b> for those who don't understand how the actual evolution of the system works, as integrated by the effects of various interacting factors at <strike>various </strike>every point.
But it doesn't really apply.
<b>*</b> Actually, the effect of more CO2 should be represented as a change to the <b>derivative WRT time</b> of the temperature field at any one point, or even more precisely as <b>one term</b> of a sum representing that derivative, with other terms from other sources (such as evaporation and conduction to surrounding air) also changing.
Comment on A War Against Fire by AK
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Comment on A War Against Fire by AK
To the extent that “ECS” (or “TCR”) actually exist as invariant numbers, a PFD for the value should have a tail that extends past zero.
S/B “PDF” of course. Fat finger.
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Comment on A War Against Fire by Turbulent Eddie
VVhy do you vvrite that?
Oscar VVilde vvrote:
VVas he vvrong?
I vvonder.
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Comment on A War Against Fire by stevenreincarnated
Your mistake is in your initial assumption that the feedback loops would be the same. Here are a couple of papers that argue depth of solar penetration affects ocean currents.
http://link.springer.com/article/10.1007/s00343-015-3343-3
http://www.tellusa.net/index.php/tellusa/article/view/25313
If the depth of penetration actually does affect ocean currents then it is reasonable to expect that SW and LW radiation will not have the same feedbacks. There are also arguments regarding the latitude of the forcing. I believe it was the IPCC 3 report that listed different sensitivities for different forcings based upon primarily latitude, but to be honest I didn’t find their differences large enough to do a follow up. The SW vs LW is much more interesting as it could completely change arguments regarding sensitivity.
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Comment on A War Against Fire by blouis79
Of course the very phrase “equilibrium climate sensitivity” is an oxymoron.
But I am still waiting to see an experiment to determine if the radiative equilbrium temperature of any passively heated sphere is space is determined only by the solar “constant” and is independent of *any* surface property.
Some argue that absoprtivity and emissivity of a selective surface at thermal equilibrium can be unequal. This notion contradicts KIrchoff.
One could argue that my proposition is just a restatement of Kirchoff’s Law. Simple conceptually and mathematically but hard for people to get their head around, like the acceleration of a hammer and an feather under gravity in a vacuum.
Anyone with access to a physics lab please help…… there is only one right answer.
And BTW I have not seen any results of any thermodynamic experiment demonstrating thermalisation of IR by *any* GHG. Radiative transfer data all comes from an experimental setup within an IR reflective chamber with IR pumped in and no prospect of free emission of IR to zeroK.
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Comment on A War Against Fire by blouis79
The essential physics is the classical analysis of the radiative equilibrium temperature of a sphere. This assumes of course that the sun is the major source of heat.
Would an earth with no sun be zero K? Obviously not, since it has a molten core.
Classical physics still says that heat energy causes temperature to rise. This statement is undeniable. Bodies of water with a high specific heat can absorb more erngy without warming as much.
Fossil fuel burning represents release of stored potential energy which stared from sunlight a long time ago. Any scheme to try to absorb sunlight and immediately use it as energy which ultimately ends up as heat in the atmosphere does nothing except add more heat to the earth. Only transforming solar energy to stored chemical potential energy uses up the heat energy.
In homes, solar is completely useless for combating warming caused by heat energy.
Nothing I have said is scientifically controversial. Except in the religous war over global warming and GHGs.
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Comment on NOAA fails walrus science by 50+ Failures and Deceptions of Global Warming Models and Climate Scientists | UnderstandItAll
[…] 1D) FAIL: The Walruses are not dying off. […]
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Comment on A War Against Fire by Arch Stanton
KOKO Knows…
the signs and has a future in sales.
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Comment on A War Against Fire by Bad Andrew
…but the temperature can still go down.
Andrew
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Comment on A War Against Fire by JCH
It is interesting. Don’t know if SW with low penetration is the same as LW.
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Comment on Global Temperature Trends After Detrending with the AMO by RichardLH
Thank you Steve: A good word picture I had not considered putting forward.
I do wish to take up one point however, what you say is true for a single anomaly series. When talking about more that one, extra steps may need to be taken.
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Comment on A War Against Fire by Jim D
You can compare effects by quantifying the forcing change. Doubling CO2 has a forcing effect of 3.7 W/m2 which is equivalent to adding 1% to solar forcing. This may not seem much, but the sun never varies more than ~0.1% even between periods like the Maunder Minimum and now, or between sunspot maxima and minima, but even those changes are detectable in the temperature record. Doubling CO2 is an order of magnitude larger in a quantitative sense. We are already at 2 W/m2 which is why heat records are being broken all the time. It is very straightforwards.
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Comment on A War Against Fire by curryja
yes I’ve spotted this
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Comment on A War Against Fire by Steven Mosher
Geoff. Don’t be stupid.
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Comment on A War Against Fire by Steven Mosher
Not an oxymoron.
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Comment on A War Against Fire by David Wojick
We have been discussing this in my Climatechangedebate.org Yahoo! group. Fascinating emails. Looks like dangerous OA is entirely speculative. Asserting conjectures as facts is bias #11 in my taxonomy of 15 funding induced biases:
http://object.cato.org/sites/cato.org/files/pubs/pdf/working-paper-29.pdf
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Comment on A War Against Fire by Steven Mosher
Seems a fair question. What part would need to have been included to avoid the apparent charge of selective quotation. I read the whole piece and it’s introduction and am confused as to what is selective about judiths selection other than the mere fact that she didn’t use 100% percent of the piece.
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Comment on A War Against Fire by andywest2012
Heh, already instilling the cultural narrative into children worldwide, they’re now making a start on apes. Cultural narratives often include an urgent agenda of self-replication via every possible route, I guess they really are leaving no possibility aside here ;)
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Comment on A War Against Fire by David Wojick
Blouis, I think you have completely missed the point of my comment, which is simply that ECS is an abstraction which is undefined and may well be irrelevant in the real world. Moreover, ECS has nothing to do with the heat released by fossil fuel combustion. That is just another aspect of the abstraction.
Bad Andrew has it right. The real temperature can still go down. A positive ECS in no way prevents this.
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Comment on A War Against Fire by climatereason
This is the one that was edited and released for the Paris climate summit wasn’t it? Someone is getting desperate. Lets hope it was all tongue in cheek
tonyb
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