Martin, you expect science to provide Rhoda with measurements that show direct connection between CO2 and temperature rise and yet you are content to rely on hand waving ("the only conceivable source...") to explain spring melting. Measuring solar radiation at 150,000km distance from the source is not what I would call direct, but maybe you have a different definition of the word "direct". Measuring the vibrational and radiative changes in an ice crystal that result once the SW radiation from the sun has been absorbed, reradiated as infrared distributed by GHGs, reabsorbed etc is not something I think you could do directly.

We do understand in detail the behaviour of CO2 with respect to infra red radiation, the gas laws of the atmosphere etc. These things have been measured directly over the last century an more. We know for sure that an increase in CO2 causes energy to accumulate on Earth. The unknowns are secondary, such as the level of feedbacks, time constants, circulatory changes etc. But the primary change, the accumulation of energy, is not reasonably in dispute. And we can measure that in ocean temperature changes.

Mike the direct correlation is between CO2 increase and energy accumulation. Energy accumulates until temperatures have increase sufficiently to restore balance. This may have been mis-sold by the entire climate science community as implying a linear correlation to land surface temperatures - or there may have been a variety of messages some more balanced than others; I don't know. We know now that those who proposed a linear correlation were probably wrong. Gee, I apologise to you on their behalf. But let's put that behinds us because it does not change the fundamental correlation of CO2 to energy accumulation.

ssat, you said, "Note "Higher up is colder.". This is not 'Higher up becomes warmer'. He is specifically saying that more GH gases reduce the outgoing radiation, upset the radiative balance and add energy into the system. An entirely different description to a greater height for OLR increasing surface temperature via the lapse rate." Maybe you are missing the unspoken corollary - that the radiative imbalance causes temperatures to change until the "higher up" does indeed become warmer and the imbalance is gone.

Mike, its also one of EM's favourite habits: Switching from arguing about temperatures (because they are not going up as the models predicted) to talking about energy accumulation instead while omitting to acknowledge that energy accumulation cannot be determined in the real world without first measuring temperature changes.

Raff,

" Maybe you are missing the unspoken corollary - that the radiative imbalance causes temperatures to change until the "higher up" does indeed become warmer and the imbalance is gone."

Not at all. That is exactly my point. Now consider how long it takes for that radiative imbalance to be gone: a) the time it takes for a photon to be thermalised by an additional CO2 molecule, or b) the time it takes for that thermalised CO2 to conduct to a non-GHG or c) a fortnight or d) ...?

Mike, if I Google "energy accumulation" climate change I get 64000 hits. If I search Google scholar for the same I get 1640 hits. What you are noticing is that the term "energy accumulation" is used in scientific discussions, which would of course be unfamiliar to many regulars here. All the same I am flattered that you cannot tell me apart from a physicist.

It doesn't really concern me that you and others refuse to accept the GHE. In fact it is a positive boon - any time anyone suggests skeptics have some credibility, I just point them here.

michael, energy accumulation and temperature change are two sides of the same coin. If you find it confusing, bear in mind that accumulation of energy results in a temperature change, then you'll be alright.

ssat, er what? See my comment to Mike, above.

Ssat

"Now consider how long it takes for that radiative imbalance to be gone: a) the time it takes for a photon to be thermalised by an additional CO2 molecule, or b) the time it takes for that thermalised CO2 to conduct to a non-GHG or c) a fortnight or d) ...?

The correct answer is d)

The radiative imbalance disappears when the climate has heated up enough and the heat capacity is very large.

Raff

"er what"

It was a simple question: how long does the radiative imbalance last for each additional molecule, mole or tonne of CO2? You said "until the radiative imbalance is gone". Just wondering how long 'until' would be. Of course, if it was a nanosecond then there would be no acumulated energy to worry about so I would be interested to know how long it actually is.

ssat, this discussion has been going on for ten pages and the process by which the GHE occurs has been well described by SoD, amongst others. Your question gives the impression that you haven't understood any of it.

"michael, energy accumulation and temperature change are two sides of the same coin. If you find it confusing, bear in mind that accumulation of energy results in a temperature change, then you'll be alright."

Aug 31, 2014 at 11:54 PM | Unregistered CommenterRaff

But 'accumulating energy' is not how the coming catastrophe is being sold. 'Thermageddon' is declared when the temperature has gone up 2 degrees C. If we can accumulate energy without the temperature going up very much at all, thermageddon is presumably postponed - quite a lot? So maybe we have quite a lot more time to sort the problem out? Maybe we don't need to decarbonise quite so fast - and expensively?

SoD;

The correct answer is d)
The radiative imbalance disappears when the climate has heated up enough and the heat capacity is very large.

Thank you for that. It would seem that we have now arrived at the question of climate sensitivity to anthropogenic CO2.

Ssat:

"It would seem that we have now arrived at the question of climate sensitivity to anthropogenic CO2."

Oh, now a hard question.

In fact, it's not "climate sensitivity to anthropogenic CO2" or even "climate sensitivity to CO2", it's climate sensitivity to well distributed radiative forcing. Anyway, this is why the massive questioning of radiative physics basics with "why hasn't the surface temperature changed for 17 years" is so bemusing.

(Bemusing only in one sense, because I realize most people haven't understood the physics basics).

Anyway, radiative heat transfer, even through gases, can be turned into a simple 1d problem with a well understood equation from fundamental physics, and well known parameters measured in a lab and verified in the atmosphere. (Obviously the earth is 3d - you integrate this 1d equation over the surface of the earth).

Contrast that with turbulent flows of the atmosphere and the ocean. That problem is seriously difficult. See Turbulence, Closure and Parameterization.

So climate sensitivity to radiative forcing.. Is it a constant? Can it be measured? What do climate models tells us? What does past climate tell us? Probably needs a new discussion.

Martin A

The IPCC remit is to publish reports at intervals. These are expected to review the current state of the science and use it to project future conditions as a guide for those making policy. The IPCC regard CO2 increase as the driver for increased radiative forcing and the subsequent temperature change, and phrase their definition accordingly.

The more general definition could be used with any source of radiative forcing. For example, if the solar output increased by 1% it would probably increase temperature. Surface insolation is about 280W/M2. Simplifying a little, a 1% increase would add 2.8W. The IPCC estimate of the link between forcing and global temperature is 3.8W/C. The extra 1% solar forcing would produce 2.8/3.8 or 0.74C warming.

The same technique would apply to changes in albedo, cloud cover or any other forcing effect.I get requests here for ways to disprove AGW. How about good data showing changes in non-CO2 forcing which would generate the observed temperature changes?

"It's hard to disagree with unquantified statements." No it is not. Turn it round and you get:

We know for sure that an increase in CO2 causes energy to dissipate from Earth.

I disagree with that, quantified or not. You?

But to be "sure" about a thing that has been hypothesised but depends unverified assumptions and has not measured does not make sense.

Again no. I am sure that nothing I say will convince you to change your mind about CO2. I base that on assumptions about you gleaned from our short acquaintance. Do you think it makes no sense?

SoD's rephrasing of sensitivity to relate to radiative forcing, not CO2, is because it is the forcing that causes temperature change (and forcing need not come from CO2 change). And increased CO2 does result unequivocally in increased radiative forcing. He has an amusing piece for those who like to dispute it still.

Martin A

The measured insolation, OLR, DWLR, temperature and calculated energy budgets of this planet Venus, Mars and Titan are consistent with the physics of radiation and heat transfer derived from theory and confirmed by laboratory experiment. On Earth these are changing as one would expect if AGW is taking place, subject to the usual confidence limits and other noise generating variables.

Over the period for which we have direct measurements the only driving variable which has changed significantly is CO2 concentration.

That is probably as good as any of us will get without replicate planets on which to do controlled trials.

I did explain a little more about radiative forcing in Wonderland, Radiative Forcing and the Rate of Inflation (and a follow up part), because, like the rate of inflation, it's a handy ready reckoner, but doesn't give the whole story.

A while back papers would compare the GCM response of doubling CO2 vs a 2% increase in solar..

The link above mostly discussed a paper by Hansen and others:

"We examine the sensitivity of a climate model to a wide range of radiative forcings, including change of solar irradiance, atmospheric CO2, O3, CFCs, clouds, aerosols, surface albedo, and “ghost” forcing introduced at arbitrary heights, latitudes, longitudes, season, and times of day.."

Micky H Corbett

I haven't tried to do it myself, but NASA's Panoply software might help.

But that does not mean it is unreasonable to keep pointing out that the thing has not been directly shown in reality.

Well it depends upon the circumstances, the time and place. If you were to keep doing so amongst climate scientists who are very well aware of the limitations to their knowledge you might find that they considered it tedious and indeed unreasonable. But you are right, in the context of a blog the aim of which is (in the words of BBD over at ATTP's place) "to inject a constant stream of misinformation and fake controversy into the public discourse" it is of course entirely reasonable.

SoD, thanks for taking the time to post here.

I'm particularly interested in your responses to Martin-A above, most specifically relating to the "..it's climate sensitivity to well distributed radiative forcing" bit, which so often seems to imply some near-equilibrium considerations in frequent blog discussions at other locations.

I rarely, if ever, get much traction when posing questions that start with "...but much of the atmosphere is not in equilibrium, so would CO2 not actually increase radiative losses to space in certain regions such as, say, sub-tropical regions where there is 'adiabatic' warming of low-humidity air..."

Is that included in what you think is worth a separate discussion, or is it covered in your blog-posts mentioned above (it's a while since I've visited your site.)