Bishop Hill The IPCC versus Stevens
Mar 20, 2015 Climate: sensitivity I've updated Nic Lewis's graph of his new climate sensitivity estimates by adding the IPCC's likely range of 1.5°C–4.5°C as a grey box. Something of a contrast here I would say.
;)
The situation for TCR is only marginally better.
;)
Bishop Hill
In the comments at CA, Shub and Nic Lewis point to another important implication of the Stevens paper:
SHUB: Do low estimates for aerosol cooling imply the 1940-1978 drop in global temperatures were not due to coal plant emissions from post-war industrialization?
LEWIS: Yes, they strongly suggest that the main reason for global temperature going down rather than up from 1940 to the mid-1970s despite quite strong greenhouse gas forcing (+0.7 W/m2 for long-lived GHG, +0.85 W/m2 including ozone) lay elsewhere. Internal variability (here the AMO) seems the obvious cause. On Steven’s best estimates, aerosol forcing became a bit under -0.3 W/m2 more negative during this period. Sulphate emissions from coal plants etc. grew rapidly and reached their peak level in the mid/late 1970s.
Reader Comments (134)
It works perfectly. Do the calculation yourself. Since there is no atmosphere, you can approximate each square metre of the moon as an independent absorber and emitter. Consider 1 square metre at the equator at at a time when that patch is pointing directly towards the Sun. If there is blackbody energy balance you would expect
(pi R_sun^2 sigma T_sun^4)/(pi a^2) = sigma T_ss^4,
where some of the variables should be obvious, but a is the distance of the Moon (Earth) from the Sun and T_ss is the temperature of the subsolar point (i.e., a one square metre patch on the surface of the Moon directly facing the Sun). Look up the numbers, solve the equation, and compare what you get with the values in your link. If you want to get more complex you can do the above and include corrections for latitude and longitude.
ATTP:
If the feedback from CO2/H2O AKA global warming is so strong, how does the earth oscillate in and out of ice ages?
What is the additional negative forcing, in phase with Milankovitch periodicities on the temperature downswing but not present on the upswing, that gets you back to an ice age after the dominant effects of CO2/H2O accelerating the warming?
" Paleoclimate - how did we move into and out of glacial periods if ECS is this
low?"
Ice and snow cover does a great job of reflecting sunlight straight back out to space hence you get a very non linear melting/warming effect as the ice sheets retreat. Obviously we are still recovering from the last glaciation by the fact the oceans are much colder than the atmosphere/surface.
Facepalm.
Please actually consider what I wrote, not what you thought I wrote. Of course it is trivial to substitute in the Bond albedo to the SB equation and agree with the notional 270 degree black body average. However the measured temperature of the moon is on average much, much lower. Your attempt at an answer to the conundrum doesn't even begin to address the necessary physics.
To Rob Burton: MY question was how do you get BACK to an ice age after all the warming caused by the feedback from CO2/H20? As the ice sheets retreat the Earth reflects less, and at the same time apparently we have an increasingly positive feedback system from CO2/H20.
So what even greater negative forcing overcomes all this and gets us back to an ice age?
It,
You claimed that the simple BB doesn't work without an atmosphere and I was simply pointing out that without an atmosphere you would typically need to treat every patch as largely independent since there is no easy way to transfer energy across latitudes and longitudes. If you do that, you recover the temperature variations on the Moon that the data that you linked to shows. That shows that the simple BB does work.
Also, we refer to the equilibrium temperature of the Earth as being 255K because that is the temperature a blackbody emitting the same amount of energy as the Earth would have. What I think you would need to do for the Moon is to calculate how much energy it is emitting (by considering every patch of the surface) and then equate that to a BB temperature. The NASA link is simply averaging the temperature, which isn't necessarily the same thing.
thinkingscientist,
The current idea (and I accept that there isn't a defintive mechanism) is that both the move into and out of glacial periods is triggered by orbital forcing. The small changes in the orbital eccentricity and inclination change the Solar insolation and also where the insolation dominates. For example, the overal change in insolation is small, but the changes at high northern latitudes can be high. If we're in an inter-glacial, then this orbital variation can reduce the insolation at high northern latitudes causing the Northern ice sheets to start growing. This increases the albedo and we start cooling. As we cool, the oceans take up more CO2, so atmospheric CO2 drops, which also produces cooling. Consequently, we move back into a glacial. That's my understanding, at least.
Sorry, should have said "in a glacial" not "in an inter-glacial" above.
ATTP:
So you really don't know the answer, do you? You see, when I asked you the self-same question that has now been asked by at least two other commenters, all you could do was patronise me.BTW: When you were made aware of the fact that NASA had measured the moon @270K (ave 206K) you ignored the measured figure and came back with formula as a means of BS-ing the question. Don't you accept real measurements? What did you get your formula to come up with?
Anders asks:
Paleoclimate - how did we move into and out of glacial periods if ECS is this low?
Because the icecap isulates circulating warm equatorial water which accumulates enegry under it until it melts through from below as insolation increases above. Whoosh - lots of energy escapes and humidity feeds back.
Greenhouse effect - how can it be 33K if ECS is this low?
Because oceans get warmer under the zenith Sun than any stupidly misconcieved 255K limit, dummy.
Harry,
I think the 206 is at the Equator only. I haven't done the complete calculation but if you wanted to know the effective temperature of the Moon you should really determine the average amount of energy it radiates per square metre per second and then convert that into a BB temperature. Averaging the actual temperature is not the right way to do that.
" MY question was how do you get BACK to an ice age after all
the warming caused by the feedback from CO2/H20? "
What CO2 water feedback?. I can't see how CO2 influences glaciation at all.
ATTP:
So I can take it you feel the same about the GAT (whatever that is). Interesting times."Paleoclimate - how did we move into and out of glacial periods if ECS is this low?
Greenhouse effect - how can it be 33K if ECS is this low?
Mar 20, 2015 at 9:19 AM | Unregistered Commenter...and Then There's Physics"
Paleoclimate analysis of both CO2 and dust(aerosol) would imply that warming and cooling is more likely to be caused by the >3-orders of magnitude change in atmospheric aerosols, than in atmospheric CO2.
If one were to run paleoclimatic models that include both aerosols and CO2, one could see if the 'forcings' attributed to each makes sense.
Greenhouse effect - how can it be 33K if ECS is this low?
I would hazard a guess that the system, which is a biotic and aqua planet, is rather more complex than you imagine and that the phase-transitions of water blow away simple analysis.
Harry,
Well, in that case we're average anomalies, rather than actual temperatures. Plus, in that case we're interested in how it is changing, rather than it's actual value.
Rob,
Well, if CO2 levels drop, we will cool. This will lead to a reduction in water vapour and other feedback effects, leading to further cooling.
Note how the Pinatubo aerosols are modeled in the IPCC reports. Very cold!
And:
If you bothered to look at the link you would see the temperature curves through time at one longitude at an assortment of latitudes on the moon. The average and instantaneous temperature at the equator is naturally the highest, but is still way below the theoretical black body temperature which is supposedly an average for the entire body. You have completely missed the effects of emissivity (and its lack of relationship to Bond albedo, which is concerned with reflection) and the long lunar night.
And - you call yourself a physicist.
It,
I'll try one more time, although given your tone I know I shouldn't. At least think about this, just for a moment. If you want to determine the average BB temperature of the Moon you need to determine the average of the energy emitted per second per square metre and then convert that into a BB temperature. This is not going to be the same as the average of the temperatures.
Consider the following as a simple test. If you look at the figure in your link, we could crudely estimate the equator as spending half the time at 300K and half at 100K. This gives an average temperature of 200K. Now consider the energies. The average energy emitted per square metre per second is:
(sigma 300^4 + sigma 100^4)/2 = 235 W/m^2.
Now use this to estimate an effective BB temperature from
sigma T^4 = 235 \Rightarrow T = (235/sigma)^0.25 = 254 K.
So, higher than the average temperature of 200K. That's only crude and I'm not claiming that it's the right answer, but it's clear that the effective BB temperature is not the same as the average of the temperatures and can be much higher. Well, assuming I've done that correctly.
"Consider the following as a simple test. If you look at the figure in your link, we could crudely estimate the equator as spending half the time at 300K and half at 100K"
You cannot 'average' temperature like this you idiot.
Attp
" As we cool, the oceans take up more CO2, so atmospheric CO2 drops"
So CO2 follows temperature - that's what I always thought.
ATTP:
Like I said, no self awareness. Tsk tsk.ATTP:
I was not aware that GAT (whatever that is) was expressed in anomalies. That's new.ATTP says
Ok, agreed.
Agreed, and we go back to an ice age.
Ok, agreed. So CO2 follows temperature. So the global warming effect must be small otherwise Milankovitch could not overcome it.
Lets start at the beginning.
1. We are in an ice age
2. Milankovitch periodicity changes insolation at high latitudes causing melting of ice sheets causing warming
3. CO2 comes out of oceans and starts causing global warming, apparently exacerbated by multiplying factor of H2O in the form of water vapour. This forcing is apparently significant in this model, because Milankovitch alone is not enough to give us all the warming (so the story goes).
4. So having reached a high CO2 in atmosphere, how does the piddly little Milankovitch effect overcome the greenhouse effect from all that CO2 and return us to ice age?
Either the CO2/water vapour effect is big and this would be a one time event ice age to interglacial
OR
Milankovitch rules and we have periodic ice ages and CO2/water vapour effect is small.
Trying to invoke a significant CO2/water vapour effect does not allow you to return to the ice age. CO2/water vapour cannot cause cyclicity unless you can explain why it cycles. And if it depends on Milankovitch cycles itself then it is an effect, not a cause, and will always lag temperature....
The simplest model is that Milankovitch controls ice ages. If CO2/water vapour (GW) create significant warming, the combined effect will be Milankovitch + GW. If you then subtract Milankovitch as its forcing wanes due to orbital periodicity, you are still left with GW...and no ice age ever again.
The 1910-1940 warming rate initially plotted steeply and this rate of warming was adjusted downward with the ship/bucket story. The rationale behind the move was that the temperature change looked too abrupt and therefore was obviously wrong. The 1940-1970 cooling was equally abrupt for which Jones, and others, proposed the aerosol cooling-based adjustments that moderate the rate, i.e., the rate of cooling was adjusted downwards. Estimates for sensitivity are then tuned against the instrumental record. Clearly there is no beginning or end to the chain of inference.
ATTP, do you feel the sting of hypocrisy being able to insult/denigrate anyone at will? :)
Is it me? I normally like having people come on here and challenge our views, ideas, science, but this ATTP chap takes the biscuit. First off, as physicists go he doesn't seem to be in the Premier League, but simultaneously gives the impression he thinks he's the Lionel Messi of physics. Secondly patronising doesn't do him justice and thirdly his ignorance is staggering.
He does exist he's called Ken Rice and seems to be a family man, an academic who clearly doesn't work on Fridays and one who believes ice ages are triggered by a reduction of water vapour in the atmosphere.
No wonder SkS won't let him into the gang hut.
:) Mike, consider this. If the adjusted global record is the standard, the new aerosol 'forcing' can't cool enough to produce even the reduced rate of cooling. No wonder the models can't warm the 1910-40's enough, can't cool the 1940-70s enough, can't cool the 1998-2014 enough ...
Does anyone else find it interesting that Nic Lewis posted up a thread at Climate Audit, then Bishop Hill summed it up in a couple of quick posts and at this moment in time Professor "and Then There's Physics" has posted close to twenty comments casting aspersions on Nic's post at Bishop Hill and close to zero comments at Climate Audit?
Has "and Then There's Physics" been banned from Climate Audit? (I really doubt it)
Does "and Then There's Physics" have difficulty following Bishop Hill's link to Nic's original post? (I really doubt it)
Does "and Then There's Physics" believe the people following Bishop Hill are more likely to be swayed by pedantic swagger?
ATTP:
I would agree. So please explain why you argued earlier in this post that, based on SB calculation using AVERAGE insolation the BB temp would be 255 K, but its actually about 288 K and therefore 33 K is the global warming effect?
You can do the averaging, but you cannot put average insolation into S-B and get a correct answer because its a T^4 function. Still, you can continue arguing until you are blue in the face. You have made the classic mistake of many who turn up here and think that we are all ignorant.
So, at the equator with the sun directly overhead the S-B equation would give a surface temperature of around +88 deg C (360 K). Of course it never gets to that temperature because of the incredible properties of water and huge heat transport mechanisms a la convection. So the temperature stays pretty much in the 30 - 36 degC range. CO2 is utterly dwarfed by these mechanisms.
And while we are on the subject, Milankovitch related insolation changes at the poles are of the order of 100 W m^2 Ie very big and you don't need piddly CO2 effects to explain ice ages. CO2 is a follower, it has a bit part.
Harry Passfield: "I was not aware that GAT (whatever that is) was expressed in anomalies. That's new."
First off you've spotted the problem, you can't have a global average temperature of a planet that varies between -80C and +50C that would be plain daft, but if you want to get a signal from the temperature record you can take the global average temperature and then, provided it was measured in exactly the same way, with exactly the same locations, the anomaly from the original average could have some useful information in it. So if the GATA is higher it would indicate that the Earth has warmed, and if it is lower the Earth has cooled.
It's one of those things that climate scientists do that would be ripped to pieces if anything important depended on it. Most people understand that an average which is comprised of temperatures of -80C and +50C is useless (not out visitor apparently), however it's become accepted that the GATA has a signal in it and to argue against this is unscientific. So most people don't argue because they're chasing a bigger picture i.e. are the policies useful.
Personally I don't believe it would take too long to prove the GATA was a waste of space and meaningless in terms of providing evidence of anything.
Guy's
You're wasting bandwidth trying to discuss anything with ATTP. He is a legend in his own mind, he is right and you're wrong and nothing will ever change that.
He seems to be incapable of considering data in an objective manner. Heaven forbid you ask him to consider that climate might just be a chaotic multivariate entity for which, despite all our efforts,we do not yet know what all the variables are, never mind their relative importance and expected range of values.
thinkingscientist,
Because 225K is the average BB temperature based on the energy emitted from the Earth into space and 288K is the average BB temperature based on the energy emitted from the surface. Hence, the difference is 33K.
I don't know what you're getting at here. I've only ever been talking about an average BB temperature based on the average energy emitted per square metre per second (i.e., the temperature of a BB emitting the same amount of energy per square metre per second).
I've never claimed that people here are ignorant. Maybe you shouldn't assume that's what I think?
ATTP:
Weird. I thought you understood the physics. In S-B the average energy emitted is based on the temperature at that point. At the equator with the sun overhead the S-B temperature would be +88 degC. You need to integrate across the surface of the earth, in T^4 (in Kelvin), not average the insolation across a circle.
But you are still happy to say:
In one swoop of averaging we conclude the GH effect is 33K......as others pointed out above, the S-B equation doesn't even work correctly for the surface temperature of the moon, and that doesn't even have an atmosphere. Still, never let facts get in the way of a good theory, eh?
So what temperature do you get if you calculate the actual S-B T^4 temp over a hemisphere facing the sun and then average that? I'll give you a clue - its a lot higher than 255K.
thinkingscientist,
Yes, I know, that's what I'm trying to say. You integrate over the entire planet/Moon to determine the total amount of energy that it is emitting per second and then divide by the total surface area to get an average per square metre per second. You can then use that to determine an average BB temperature by simply solving (for T)
sigma T^4 = average energy emitted per square metre per second
Yes, it does. The moon absorbs about 308 W/m^2 of energy from Sun (average over the entire surface of the Moon). This means that to be in energy equilibrium it must emit the same amount of energy per square metre per second (determined by integrating over the entire surface of the Moon and then dividing by the surface area). This is the same amount of energy per square metre per second emitted by a BB with a temperature of 271K. Therefore the effective temperature of the Moon is 271K.
Maybe you should consider that this was a somewhat ironic thing to say:
Yet again ATTP shows that he understands neither heat transfer, fluid flow nor thermodynamics. Remind us, what branch of physics is his "speciality". Is it the physics of green?
Jeff,
It's because I feel so welcome here :-)
Always the talking prat:
You never do intend to tell the truth here false one.
You are here solely to spin false premise and waste as much commenter time and research as you possibly can.
Phrased simply; you are a waste of everyone's time, especially your own.
It might save time and indignation for ATTP to give Harry an atmospheric science textbook so he can tear out the pages with which he disagrees.
Yeah, as several people have pointed out, a high ECS is a very poor explanation for the glaciation cycles - and there are numerous better alternatives. Obviously I have my pet explanation (fractal dynamics) which explains the cycles far better than a high ECS.
Many people have now pointed this out and it is clear from a lack of response from ATTP suggests to me he has no answer to it.
Another aside: even though the 33K figure is problematic for so many reasons discussed above, and even though water vapour dominates the GHG effect on earth anyway, it is also important to note that the logarithmic nature of CO2 GHG "forcing" makes it difficult to determine what is a large temperature delta. After all, a logarithmic forcing can regress infinitely - you just keep halving it. Of course, there will come a point where the logarithmic relationship will break down - since homoeopathic quantities of CO2 clearly won't have any effect. But without determining where that transition happens, what counts as a large temperature difference?
If these are the best examples ATTP has got, this has to be the weakest scientific case I've seen in quite some time.
Russell - one of ATTP's textbooks? Have you ever tried tearing vellum?
ATTP,
I am glad that you came to post here and could have
a discussion with Nullius. Just because a few people
here are less polite is no reason for you to regret posting.
Attp:
So you agree we have to integrate across the surface as t^4, not use average insolation. So try answering my question then:
So what temperature do you get if you calculate the actual S-B T^4 temp over a hemisphere facing the sun and then average that? I'll give you a clue - its a lot higher than 255K.
When you answer tht, I'll pose the second part of the question
Good luck!
Shub (4:49 PM): where is this ship/bucket myth from? I first saw it a few threads back, where someone posted that the buckets were lowered to several metres below the surface, and that engine cooling water intakes were used instead. As the met readings were of sea-surface, that does not make any sense, apart from the simple fact that collecting a bucket-load of water from anywhere other than the sea surface on a moving ship would not be possible, and I doubt that any selected met ship (being primarily commercial vessels) would stop every six hours for a reading. Engine cooling intakes can vary from anywhere like 2 metres to 20 metres below the surface; hardly what one could consider scientific in its variability, let alone that the thermometers used in ER intakes are not of the standard that should be used for met readings.
thinkingscientist,
Look, I've rather lost interest. You've managed to largely misinterpret most of what I've said so far, so I have no confidence that it's going to change if we continue. If you're genuinely interested in a decent discussion, try posting a comment that is worth responding to. Alternatively, post a comment that fully explains your point. Games are tedious, especially when the person playing them hasn't been engaging in good faith in the first place.
ATTP:
Finally! Some measure of self-awareness! It is but the beginning...as was to be expected, ATTP has retreated to his sulk blog and moans about this blogpost. Interestingly, he is seeking to find support for his pet ideas:
So he obviously has no way of responding to the alternative theories thrown out by spence, thinkingscientist, nullius etc. However, he is not going after proof, because how can anyone prove these ideas without some form of data...which is either in short supply, inadequate or non-existent?
I note in passing that BBD (remember him?) is always keen to talk about recovery from ice age requiring high sensitivity...despite being unable to adduce any evidence whatsoever. It is a theological game to these people. They are debating about ideas without any data - angels on pinheads.
Very amusing. Expect a double cannonade from ATTP soon, buttressed by his faithful supporters.
diogenes,
Jeepers, you're sensitive. I think the exact words I used were It’s also mentioned on Bishop-Hill. That's a real moan a half.
I think Spence used some complicated words, which I - obviously - ignored. Nullius and I had a discussion and agreed. TS pointed out that if you average the temperature on the Moon it is less than the expected BB temperature, which is true and obvious and doesn't mean that the simple BB model doesn't work! What else am I meant to say?
ATTP
Imagine I take a block of carbon and place it in a vacuum chamber, with the walls of the chamber maintained at 77K, and wait for the block to reach 77K.
Now, I shine a solid state laser on to the face of the block. Now during the first second, does the absorption, emission and temperature of the block follow S-B's Law? No? What about the second second? How about in the first hour?
Think is that S-B applies to steady states or equilibria?
I can pump more energy into systems and not get a S-B relationship between temperature.
I am not sure if I illuminate sea water with the same amount of heat energy at 400 nm that I will get the same effect as with photons at 800 or 1600 nm. I suspect that if I radiate water at some wavelengths I am much more likely to have molecules on the surface undergo a liquid to gas transition, than using wavelengths that will only get absorbed deeper down.
The whole point about emissitivty=absorbance is rather fun when you look at the radiation, solar and atmospheric, radiating the oceans, and being absorbed at different depths.
Paul Matthews--
Here is the full paper. Sorry if someone has already linked--I scrolled down without reading intervening comments.
https://dl.dropboxusercontent.com/u/75831381/Stevens%20lower%20bound%20on%20aerosol%20forcing.pdf
No, Harry, you should take a look at a climate science textbook somewhat more up to date than the copy of Aristotle's Meteora that presently informs your discourse.
Here's a good place to start- unless you have a problem with Chicago School Economics"
http://geosci.uchicago.edu/~rtp1/PrinciplesPlanetaryClimate/index.html
Kaire !