Skeptic: "Ah, good. MW has posted that chart from the IPCC's report*. Now look closely. Do you see that it shows 390 W/m2 being radiated from the surface, a tenth of which goes straight back into space (it's not at a frequency that clouds or other greenhouse gases can stop), and out of the remaining 350 W/m2, 324 is back radiation?"
Warmenist: "Yes, I can see it. What's your point?"
Skeptic [triumphantly]: "We've agreed that carbon dioxide concentrations have gone up (by a third, in your terms; by 0.01% in my terms); and I've conceded that this may well be due to man-made emissions. But look, you keep talking about 'runaway global warming' and 'tipping points', but according to that chart, increasing the amount of carbon dioxide in the atmosphere can't make the slightest bit of difference.
We are already getting 93% of infra-red radiation from the earth's surface reflected back to us (324 W/m2 out of 350 W/m2)**. Notwithstanding the fact that water vapour is a far more important factor, even if we doubled or trebled the amount of carbon dioxide in the atmosphere, the most that could be reflected is 350 W/m2.
We're getting a total of 522 W/m2 energy anyway (198 W/m2 from the sun and 324 W/m2 in back-radiation); in the highly unlikely scenario that all 350 W/m2 infra-red radiation from the surface were reflected back down to us, the total energy hitting the surface would only go up to 548 W/m2, that's an increase of 5%, absolute worst case, even before taking into account that a warmer surface means more cloud cover which cools us down again, and so on"
Warmenist: "Ah yes, but what about methane? Have you ever thought about going vegetarian?"
* The global radiation budget as published in IPCC TAR Chapter 1.2.1, from here.
** Logic says that this 93% figure is wildly exaggerated. Gases cannot 'reflect' infra-red, individual molecules or atoms can merely absorb and immediately re-emit it. Assuming the direction in which infra-red is re-emitted is entirely random, and at a molecular or atomic level it almost certainly is, then 50% will be re-emitted downwards and 50% will be re-emitted upwards into space. In the interests of getting an answer to this, I have posted the same question over at Devil's Kitchen.
Quick update
6 hours ago
17 comments:
http://www.carbon-info.org/carbonnews_028.htm
Bad trees!
STB.
STB, brilliant.
"by a third, in your terms; by 0.01% in my terms". No it fucking isn't "by 0.01%", it's by 0.01 percentage points. So much confused shite results from people saying percent when they mean percentage points that I'd like to kick the cunts to kingdom come.
D, it went up from 0.03% to 0.04%. That's why I said "up by 0.01%".
Here's an interesting chart I found on WUWT.
http://i27.tinypic.com/14b6tqo.jpg
It shows the number of stations included in the production of data with the average temperature anomaly.
Someone's been cherry picking again.
AC1, the Americans had their own ClimateGate to match the University of East Anglia's shenanigins.
"it went up from 0.03% to 0.04%. That's why I said "up by 0.01%"." Yeah, but you are wrong. It went up 33%. It went up .01 percentage points. Or, if you like finance lingo, it went up one basis point. But what it didn't bloody do is go up .01%.
D, I am quoting a typical conversation between Greenie & Skeptic. The Skeptic is allowed to play down the increase just as much as the Greenie is allowed to exaggerate it, yes? In defence of the Skeptic, he did also say "up by a third in your terms".
Mark,
I've been trying to find out if this makes sense but the articles I have read are a a bit vague, perhaps someone else can help.
In the radio world people often talk about High Fequencny (HF) radio waves being "bounced" or "reflected" off the upper atmosphere. This is incorrect, they are refracted in the same was as light passing in to water is refracted. The amount of refraction is dependent on the difference in the density of the boundary of mediums it travels through.
HF is affected more at the E and F layers of the Ionosphere (http://en.wikipedia.org/wiki/Ionosphere). To understand how it works imagine that in the E and F layers there is an infinite amount of layers each of slightly different density, as the radio wave passes through each layer it is refracted a tiny amount until eventually it is refracted back to earth.
There is energy loss in each refraction and as our radio signals are not a single frequency there is some scattering, in the same way light is scattered and we get rainbows.
That's the simple explanation and I was wondering if the same applies to IR, maybe in one of the other layers? Even if it does it does seem implausible that 93% is refracted. I would need to go and dig out some old text books to get the loss equation for HF and as they are propping up my monitor it with take some time so I'll do it later.
TGS, the analogy with radio waves pre-supposes that higher layers are THICKER than lower layers - if they were THINNER, then radio waves hitting them at an angle would be bent upwards into space and not reflected down.
In any event, radio waves going up vertically would pass straight through and not be refracted at all, which brings me back to the theory that at least half must go straight out of the atmosphere.
You need expoPercent :)
http://motls.blogspot.com/2010/01/exponential-percentages-useful-proposed.html#more
Mark W,
As noted at DKs establishment in answer to your question, infra-red radiation emitted is NOT 'reflected' by greenhouse gases in the atmosphere. It is absorbed and re-radiated by the gases.
Since it is re-radiated in all directions, some will escape to space, and some will be re-absorbed by the earth.
AC1, that guy is beyond me.
Chuckles, thanks. Of course it's "absorbed and re-radiated", I was using "reflect" as short-hand. But do you reckon it'd be no more than half re-radiated back down to earth? I can't see any other possibility, unless TGS is right (and to be fair, he is a radio engineer-type expert).
There is supposedly a 'whole lotta shaking going on' in all of this, but if we accept the radiation budget assumptions as true, and assume equilibrium conditions, it's fairly easy -
The re-radiated back down number must be 324, as otherwise the 235 emitted to space would be bigger.
i.e. If it's not being radiated into space, it is staying in the earth/atmospheric system, and is part of the AGW/greenhouse gas system.
Whether those assumptions are justified, and whether it has any relevance in the greater scheme of things, is another matter entirely.
Chuckles, let's take the numbers at face value (I always prefer taking the other side's figures and using them as evidence against their conclusion).
Of course, they do not split the 324 w/m2 up into
a) The Boyle's Law effect (atmos pressure at ground level means that temperatures are higher than average temperature of atmosphere, the whole Counting Cats logic).
b) The extra bit that arises because CO2 absorbs/re-emits infra-red (which I insist cannot be > 50%).
There is a greenie argument that says infra-red passes straight through N or O (let us assume this is true) but heats up CO2, and that the CO2 then in turn heats up the surrounding N or O.
Surely, the CO2 can only re-emit the infra-red? "Being hot" and "emitting infra-red" are the same thing, so if N and O allow infra-red from earth's surface straight through, they will allow infra-red from CO2 straight through as well?
"let's take the numbers at face value"
In that case, I've got a bridge you may be interested in....
If you examine the left hand side of the diagram, there is a claim of 168 units arriving at the surface from our friendly neighbourhood sun.
Right next to that are 24 and 78 units leaving via a couple of heat transfer mechanisms. Total 102.
168-102=66.
Do not take your eyes of the paper, but move your gaze slowly to the right. There we have our mighty 390 units leaving and 324 units careering back.
I wonder what 390 minus 324 equals?
The system is in equilibrium, albeit a dynamic one, and all the round-tripping on the right hand side does not add any energy to the mix.
Chuckles, yes of course all the + and - numbers balance out, that was the first thing I checked. But what's the proportion between a) and b) in my previous comment? That is what I want to know.
Even if b) is not true - and CO2 does indeed "warm up" and convert infra-red into actually heat that is transferred to surrounding N and O molecules, then that sort of gives and extra input into the a) part of the formula.
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