I’ve Looked at Clouds from Both Sides Now -and Before
by Roy W. Spencer, Ph. D.
…sometimes, the most powerful evidence is right in front of your face…..
I never dreamed that anyone would dispute the claim that cloud changes can cause “cloud radiative forcing” of the climate system, in addition to their role as responding to surface temperature changes (“cloud radiative feedback”). (NOTE: “Cloud radiative forcing” traditionally has multiple meanings. Caveat emptor.)
But that’s exactly what has happened. Andy Dessler’s 2010 and 2011 papers have claimed, both implicitly and explicitly, that in the context of climate, with very few exceptions, cloud changes must be the result of temperature change only.
Shortly after we became aware of Andy’s latest paper, which finally appeared in GRL on October 1, I realized the most obvious and most powerful evidence of the existence of cloud radiative forcing was staring us in the face. We had actually alluded to this in our previous papers, but there are so many ways to approach the issue that it’s easy to get sidetracked by details, and forget about the Big Picture.
Well, the following graph is the Big Picture. It shows the 3-month variations in CERES-measured global radiative energy balance (which Dessler agrees is made up of forcing and feedback), and it also shows an estimate of the radiative feedback alone using HadCRUT3 global temperature anomalies, assuming a feedback parameter (λ) of 2 Watts per sq. meter per deg (click for full-size version):
What this graph shows is very simple, but also very powerful: The radiative variations CERES measures look nothing like what the radiative feedback should look like. You can put in any feedback parameter you want (the IPCC models range from 0.91 to 1.87…I think it could be more like 3 to 6 in the real climate system), and you will come to the same conclusion.
And if CERES is measuring something very different from radiative feedback, it must — by definition — be radiative forcing (for the detail-oriented folks, forcing = Net + feedback…where Net is very close to the negative of [LW+SW]).
The above chart makes it clear that radiative feedback is only a small portion of what CERES measures. There is no way around this conclusion.
Now, our 3 previous papers on this subject have dealt with trying to understand the extent to which this large radiative forcing signal (or whatever you want to call it) corrupts the diagnosis of feedback. That such radiative forcing exists seemed to me to be beyond dispute. Apparently, it wasn’t. Dessler (2011) tries to make the case that the radiative variations measured by CERES are not enough energy to change the temperature of the ocean mixed layer…but that is a separate issue; the issue addressed by our previous 3 papers is the extent to which radiative forcing masks radiative feedback. [For those interested, over the same period of record (April 2000 through June 2010) the standard deviation of the Levitus-observed 3-month changes in temperature with time of the upper 200 meters of the global oceans corresponds to 2.5 Watts per sq. meter]
I just wanted to put this evidence out there for people to see and understand in advance. It will be indeed part of our response to Dessler 2011, but Danny Braswell and I have so many things to say about that paper, it’s going to take time to address all of the ways in which (we think) Dessler is wrong, misused our model, and misrepresented our position.
@- Stephen Wilde says: October 9, 2011 at 10:09 pm
“Of course, but the only molecules affected then evaporate earlier than they otherwise would have done and take away ALL the added energy with them due to the net cooling effect of the evaporative process.”
Okay, you claim you can get rid of all the extra energy without any rise in temperature by evaporation.
But the 1LoT means that energy is now as latent heat of water vapor. And the water vapor as a GHG is adding to the ‘greenhouse’ effect.
“Thus nothing left to add to system temperature because it gets converted to latent heat sooner, is transported upward sooner and is radiated away to space sooner.”
No, the latent heat energy is returned to the atmosphere at a lower temperature than the temperature at evaporation so the rate of energy emission is much less than it would be from the evaporating surface.
You get an increase in the water cycle, not necessarily more clouds, but more water vapor in the atmosphere acting as a GHG.
“But the 1LoT means that energy is now as latent heat of water vapor. And the water vapor as a GHG is adding to the ‘greenhouse’ effect.”
Apparently not because global humidity seems not to change much. Instead the water cycle gets faster (or larger) with no significant increase in total water vapour at any given time. The extra evaporation is matched by extra condensation. AGW theory somehow leaves out the condensation side of things.
“No, the latent heat energy is returned to the atmosphere at a lower temperature than the temperature at evaporation so the rate of energy emission is much less than it would be from the evaporating surface.”
The extra condensation at higher levels makes the energy content of those higher levels greater than it otherwise would have been. The air above is proportionately thinner than the air below so energy goes upward and out of the system faster than it would have done from the surface. You suggest that evaporation and condensation have a net warming effect for the system as a whole. That is not correct or possible and there is lots of established physics confirming that.
@- Stephen Wilde says: October 10, 2011 at 1:35 am
“Apparently not because global humidity seems not to change much. Instead the water cycle gets faster (or larger) with no significant increase in total water vapour at any given time.”
Wrong satellite measurement have detected an increase in specific humidity, the amount of water vapor present even if relative humidity, the degree of saturation of the atmosphere has remained constant. Hotter air carries more water for thesame relative humidity.
“The extra condensation at higher levels makes the energy content of those higher levels greater than it otherwise would have been. The air above is proportionately thinner than the air below so energy goes upward and out of the system faster than it would have done from the surface. ”
No, the surface emitts energy at a much higher rate because of its higher temp. E==T^4
If energy is transfered to a higher altitude but at a lower temperature half is STILL emitted downwards.
“Wrong, satellite measurement have detected an increase in specific humidity”
Very little and not accompanied by surface warming for more than 10 years which suggests natural forces dominate. Anyway the net position is unclear due to variability at different levels.
“If energy is transfered to a higher altitude but at a lower temperature half is STILL emitted downwards.”
But the downward portion does not all get as far downward as the surface because the atmosphere below is much denser than the atmosphere above. The net effect is faster loss to space than if the energy had remained at the surface all along.
How do you tax clouds?
We may need to replace the income from taxing plant food!
R. Gates says:
October 9, 2011 at 11:16 am
Taken directly from Dessler’s paper:
“And since most of the climate variations over this
period were due to ENSO, this suggests that the ability to
reproduce ENSO is what’s being tested here, not anything
directly related to equilibrium climate sensitivity.”
Question: Do you or do you not agree with this? Why or why not?
Over the short time period observed, it seems Dessler is quite correct: ENSO changes (specifically heat transport by the ocean) drives changes in surface temperatures which drive cloud formation. In short, during the short time frame involved, clouds are reacting to heat transport by the oceans, with whatever affects of clouds on actual surface temperatures to be very small when compared to the effects of ocean heat transport on surface temperatures.
————————————
And what makes the ENSO oscillate between warm and cool phases?
You skipped that step. Any CO2-based radiation involved in that?
And we are testing climate sensitivity here. A real world situation with real world measurements over a real time-frame.
Climate science relies on theory and CO2-based climate models while empirical measurements tells the real world story. Why does climate science seem to discount and ignore empirical measurements so often. The science would prefer to just change the measurements instead of trying to explain what is really going on.
Andy Dessler’s 2010 and 2011 papers have claimed, both implicitly and explicitly, that in the context of climate, with very few exceptions, cloud changes must be the result of temperature change only.
And even if Andy Dessler were correct, Willis’ work shows that the cloud change result does not imply that increased CO2 will lead to warmer climate.
I think you need a better explanation of exactly what the 3 lines in the graph represent.
I also think you might omit the words “forcing” and “feedback” and give a narration of the events and their causal connections in accurate temporal sequence.
Nick, if you can’t make that rather humble deduction for yourself based on part 6 of Dessler, I’m afraid I can’t help you. I don’t think anyone can help you.
Nick Stokes says:
October 9, 2011 at 3:02 pm
Eric Barnes says:
Eric, Roy says Dessler said “cloud changes must be the result of temperature change only”
I don’t believe he did. And I can’t find anything like that in your quote.
Re: http://wattsupwiththat.com/2010/08/05/co2-heats-the-atmosphere-a-counter-view/
I’m surprised this made it onto WUWT as it seems clearly wrong. The CO2 can be more excited than the N, and then there must be energy transfer. The notion that LTE demands they be the same is somewhat silly; LTE describes an equilibrium so if you assume equilibrium then you’re just assuming nothing changes and can’t therefore conclude on that basis “Hey, nothing changes!” In reality, of course, nearly all systems are only approaching equilibrium while being acted on by various distubances to that equilibrium.
Septic Matthew said:
“I also think you might omit the words “forcing” and “feedback” and give a narration of the events and their causal connections in accurate temporal sequence.”
Since you asked:
i) Solar variability alters the vertical temperature profile of the atmosphere from above as does oceanic variability from below.
ii) When the vertical temperature profile changes the surface pressure distribution shifts latitudinally.
iii) Cloud amounts change globally to alter solar energy uptake by the oceans as a result of those latitudinal shifts.
iv) Poleward shifts occur and the system gains energy from more sunshine into the oceans. Equatorward shifts occur and the system loses energy from less siunshine into the oceans.
v) The net thermal consequence of that latitudinal shifting is always opposite in sign to the forcing that causes it, hence the long term stability of Earth’s climate.
Although a warming system from poleward shifting allows more energy into the oceans the resulting faster exit of energy to space is enough to counter it.
Although a cooling system from equatorward shifting allows less energy into the oceans the resulting slower exit of energy to space is enough to mitigate the effects until the solar forcings change again. Except for larger long term solar changes that is which is where Milankovitch comes in.
In reply to Matt G @ur momisugly October 9, 2011 at 4:32 pm:
Can you provide a reference for your statement that clouds have declined about 5% from 1983 to 2001?
Has anyone researched the patterns of blogs on this site? It seem to me that they start off interesting with many interested contributors, and then gets bogged down in arguments between more knowledgeable people until finally it fizzles out inconclusively never to be heard of again. Then everyone hops on to the next topic and repeats the process. It starts to feel like a WUWT cycle of it’s own that is going nowhere. A strange process of information exchange that has no ultimate objective other than declaring itself to be alive and functioning. The articles are great but does anything ever get resolved?
“”””” richard verney says:
October 9, 2011 at 8:12 am
Re: DocMartyn says:
October 9, 2011 at 6:09 am
//////////////////////////////////////////
It is not really appropriate to get into this debate since it is O/T to the Spencer article.
I envisage that everyone accepts the statement that “…you know that matter radiates photons as a function of its temperature and emissivity. Cold objects radiate less energy than hot objects, if they have the same emissivity….” “””””
I’m not going to waste the space to post all of your post; you can go back and re-read it. But both of you are in need of some elementary physics schooling, that should be well understood by anybody who is reading here at WUWT.
For starters “heat” and “electromagnetic radiation” are not synonyms; in fact they have nothing to do with each other.
The earth receives virtually ZERO “heat” from the sun; it does receive vast amounts of “electromagnetic radiation”. EM Radiation in turn knows absolutely nothing about “Temperature”, which is a property that is uniquely confined to real matter (maybe anti-matter too). “Heat” is also a process (verb); not an object (noun). It is the process that increases the “Temperature” of some body of material. EM radiation requires NO material for its propagation, and it propagates at a velocity that is entirely dependent on the electrical and magnetic properties of free space; containing no real material at all.
Temperature is a measure of the mean kinetic (mechanical) energy of particles of real matter; and absent that matter, the word Temperature has no meaning whatsoever.
The heating process of course cannot (absent some outside influence) proceed from a source at one Temperature to a sink at some higher Temperature; the second law of thermodynamics precludes that; but EM radiation can freely travel from any source body to any sink, regardless of the Temperatures of either the source or the sink.
If you hold up a 16 ounce bottle of drinking water at about room Temperature, it will radiate (EM radiation) in all directons, at about 400 W/m^2, and some of that LWIR emission will eventually escape from the earth and proceed through space to the moon. let’s say we have a half moon, half in dark, and half in daylight. The day side is much hotter than your water bottle, while the dark side is much colder. Both halves will receive, and absorb the same amount of the LWIR from your water bottle.
Meanwhile, in a different direction, the same solid angle cone of EM radiation will proceed towards the sun, which is much higher Temperature than either side of the moon, as well as your water bottle. The sun will also receive and absorb the same amount of EM radiation as the moon did..
It is the “heating” process, which cannot proceed without expenditure of work from a cold body to a hot body. EM radiation which has NO understanding of Temperature whatsoever, can propagate from anywhere to anywhere else. LWIR emissions from high cold clouds, can and do radiate down to earth and get absorbed. The Temperatures have no effect on the transmission. The cloud source Temperature will determine HOW MUCH EM radiation is emitted from the clouds, or from the atmospheric gases for that matter; but that has no effect on where that radiation can travel.
“(for the detail-oriented folks, forcing = Net + feedback…where Net is very close to the negative of [LW+SW]).”
Negative forcing? Here? I must warn the others. Oh no, I’ve been shot!
“(for the detail-oriented folks, forcing = Net + feedback…where Net is very close to the negative of [LW+SW]).”
Synaptic overload? No, my seizures occur in the right hemisphere. OK, try again. Net is negative, feedback is small, so forcing must be negative. Yep, it still doesn’t make sense.
Stephen Wilde,
Is that what Dr. Spence intended to write? I mean, a translation, vs a correction?
Stephen Wilde: iv) Poleward shifts occur and the system gains energy from more sunshine into the oceans. Equatorward shifts occur and the system loses energy from less siunshine into the oceans.
Poleward shifts of clouds? Did Dr. Spencer’s post mention poleward shifts of clouds?
Septic Matthew:
It is what Roy could have written if he were to put his observations into a wider context.
He didn’t, so I’ve done it instead.
I’m curious, why no mention of ENSO? Several studies now (not just the recent one by Dessler) have discussed the importance of ENSO, especially on decadal time-scales. How can you simply ignore what is known to be an important modulator on ocean and atmospheric temperatures?
An Inquirer says:
October 10, 2011 at 8:55 am
http://isccp.giss.nasa.gov/index.html
The International Satellite Cloud Climatology Project (ISCCP). Datasets are obtained from passive measurements of IR radiation reflected and emitted by the clouds.
Climate4you has a lot of this data already in graph form ready for instant view.
http://www.climate4you.com/images/CloudCoverTotalObservationsSince1983.gif
Stephen Wilde: It is what Roy could have written if he were to put his observations into a wider context.
Could you explain for him what the red and black lines on the graph are?
“Could you explain for him what the red and black lines on the graph are?”
In my opinion, the main component would be variations in the amount of energy entering the oceans.
Though I’m open to alternative explanations and Roy might well have his own ideas for all I know. It will be interesting to see his main paper when it is published.
50.richard verney says:
October 9, 2011 at 8:12 am
My point is this. Merely because a low temperature object radiates energy, it does not follow that that energy can pass the threshold and get absorbed by a warmer object which is radiating energy at a higher state. may be it can, but may be it does not and this can be clarified only by properly constructed experimentation which to my knowledge has not been undertaken such that we simply do not know the answer to what is a very important issue in the climate science field.
This is a law, that heat always flows from hot to cold, because that is what is always observed, isn’t it? Like, rivers always flow downhill. It takes work to alter that. Sure locally, the river might hit a rock and some water forced back against the stream, but that is work done to change the direction. Heat always flows from hot to cold unless work is done to alter this. I thought this was basic knowledge. I really don’t know what to say about George E. Smith’s summary of what he thinks it is, but I too would like to see some real physical experiments proving it.. I hope he can provide these.
re: heat transfer from colder body to warmer body.
My 2c.
I believe it is “net” energy that flows downhill. Here is another perspective:
Consider the rate of cooling of a body at temperature T. Let Ta be the ambient temperature, less than T. According to newton’s law of cooling, dT/dt = -k(T – Ta).
Imagine body A to be emitting photons (which is independent of its surroundings, only on its temperature and emissivity).
The only way for A’s rate of cooling to decrease is when its emitted photons are replenished somehow from its cooler surroundings. In other words, there must be transfer of photons from the cooler surroundings to A. A similar argument could be made using EM waves instead of photons.
In the macroscopic view, heat still “flows” from hot to cold.
Thats my general idea anyway. I’m no physicist and English is not my first language but I think I have a valid point which can be refined by those more knowledgeable. I’ll be glad if someone points out the “error of my ways”.