Home/BlogI’ve been wading through James Hansen’s recent 52-page unpublished paper explaining why he thinks the cooling effect of manmade sulfate aerosols has been underestimated by climate modelers.
This is the same theme as the “cooling from Chinese pollution is canceling out carbon dioxide warming” you might have heard about recently.
As I read Hansen’s paper, I stumbled upon a sentence on page 23 that sounds like one I just wrote in a new paper we are preparing. I’m going to use Hansen’s statement — which I agree with — because it provides a good introduction to understanding the basics of climate change theory:
“…surface temperature change depends upon three factors: (1) the net climate forcing, (2) the equilibrium climate sensitivity, and (3)…..the rate at which heat is transported into the deeper ocean (beneath the mixed layer).”
To better understand those 3 factors, consider what controls how much a pot of water on the stove will warm over a short period of time. The temperature rise depends upon (1) how much you turn up the stove, or cover up the pot with a lid (“forcing”); (2) how fast the pot can lose extra heat to its surroundings as it warms, thus limiting the temperature rise (“climate sensitivity”); and (3) the depth of the water in the pot.
Most people working in this business (including the IPCC) agree that probably the biggest uncertainty in determining the extent to which manmade global warming is something we need to worry about is #2, climate sensitivity.
But not Hansen.
Hansen believes he knows climate sensitivity very accurately, based upon paleoclimate theories of what caused temperature changes hundreds of thousands to millions of years ago, and how large those temperature changes were. Most of Hansen’s climate sensitivity claims are based upon the Ice Ages and the Interglacial periods.
I must admit, it astounds me how some scientists can be so sure of theories which involve events in the distant past that we cannot measure directly. Yet we measure the entire Earth every day with a variety of satellite instruments, and we are still trying to figure out from that abundance of data how today’s climate system works!
In Hansen’s case, in order to explain the amount of warming in recent decades, he thinks he knows #2 (the climate sensitivity) is quite high, and so he has been experimenting with various realistic values for #3 (the assumed rate of heat diffusion into the deep ocean) and has decided that factor #1 (the radiative forcing of the climate system) has not been as large as everyone has been assuming. Again, this is in order to explain why surface warming has not been as strong as expected.
Now, I tend to agree with Hansen that the main portion of that forcing, from increasing CO2 (a warming effect), is known pretty well. (Please, no flaming from the sky dragon slayers out there…I already know about your arguments). So in his view there MUST be some cooling influence canceling it out. That’s where the extra dose of aerosol cooling comes in.
All modelers have already fudged in various amounts of cooling from sulfate aerosols in order to prevent their climate models from warming more than has been observed. But Hansen ALSO thinks that the real climate system does not mix heat into the deep ocean as fast as the IPCC climate models do.
Unfortunately, correcting this error (if it exists, which I think it does) would push the models in the direction of too much surface warming. Therefore, Hansen thinks this must then mean that the IPCC models are assuming too much forcing (the only remaining possibility of the 3 factors).
Of course, as Hansen correctly points out, accurate global measurements of the cooling effect of aerosols are essentially non-existent. How convenient. This means that modelers can continue to use increasing amounts of sulfate aerosols as an “excuse” for a lack of recent warming, despite the lack of quantitative evidence that this is actually occurring.
As I sometimes point out, this line of reasoning verges on blaming NO climate change on humans, too.
It is unfortunately that so few of us (me, Lindzen, Douglass, and a few others) are actively researching the OTHER possibility: that climate sensitivity has been greatly overestimated. Lindzen and Choi have a new paper in press on the subject, and Braswell and I have another that I expect to be accepted for publication in the next few days.
I sort of understand the reluctance to research the possibility, though. If climate sensitivity is low, then global warming, climate disruption, tipping points, and carbon footprints all suddenly lose their interest. And we can’t have that.
I agree with Hansen that our best line of observational evidence is how fast the oceans warm — at all depths. Our recent work on estimating climate sensitivity from the rate of warming between 1955-2010 at different depths has been very encouraging, something which I hope to provide an update on soon.
I think James “Coal Trains of Death” Hansen’s mother was scared by reading Velikovsky!!
Yahoo. You write so clearly. And you put your examples in real world terms that we laymen can understand. Thanks.
Kuhnkat
I think you and I are the only ones that still remember Velikovsky. His view of catastrophic events in the past, vs the theory of uniformity (Lyell’s, heavily supported by Darwin) has been slowly accepted over the last few decades.
I remember that Velikovsky’s Venus temperature prediction made Sagan invent the greenhouse theory for Venus. That’s what got Hansen started.
“I remember that Velikovsky’s Venus temperature prediction made Sagan invent the greenhouse theory for Venus. That’s what got Hansen started.”
Really? I remember Velikovsky. I didn’t know that he exercised Hansen.
It amazes me that we don’t have any observational evidence of the forcing effect of aerosols. Everyone knows they cause cooling, but no one knows how much. It seems like a worthwhile investment … I recall Hansen and others agitating for a relatively inexpensive piece of satellite equipment that would do just that years ago.
“Nailed!”
c.f. wattsupwith that on Hansen’s 2008 AGU presentation
If aerosol cooling is much greater than currently expected, then doesn’t that have significant impact in how you need to think about the historical record, and not to the AGW’ers advantage? How much of the early recovery from the Little Ice Age was caused by the move away from unfiltered wood and coal burning for household heating? How much of the end of the 70s cooling was caused by better clean air laws? How much of the 90’s heating was caused by the collapse of the dirty industries of the Soviet bloc?
Nicely done.
HERE WE GO AGAIN WITH MAN BEING THE CAUSE OF CLIMATE CHANGE. PATHETIC!
Geo you are EXACTLY correct. Sulfate aersols due to man are NOT the cause of the lack of warming. That is as stupid as saying co2 is the cause of warming.
Hansen and others don’t believe in past history ,even recent past history as was the the case during the Dalton and Maunder Minimum cooling events ,where no,I will repeat NO, man made aersols were present.
Point one -NET CLIMATE FORCING. Why don’t we try the sun for this one and all it’s associated feedbacks.
This is just ridiculous.
I would bet my last dime that it is not sulfate aersols as a result of man or co2 as a result of man that is somehow IMPACTING earth’s climatic system. This is ridiculous.
Also another point to consider is volcanic activity up to say the last 3 years or so has been very quiet contributing to less sulfur dioxide (cooling effects) to earth’s climatic system, not more.
Hogwash,hogwash to this.
Buzz Belleville,
“Everyone knows they cause cooling, but no one knows how much.”
I question this “popular wisdom”, as in point of fact not all aerosols or effects of them do cause cooling and I don’t think the net effect’s sign is that obvious at all. For instance, the forcing from Black Carbon Soot may be quite substantial, and currently underestimated.
In response to the idea in general that Hansen has come to believe that the aerosol forcing must be underestimated by current science, I find it fascinating how climate alarmists take advantage of our profound lack of understanding of the climate to, whenever possible, argue for the extreme tails of even the “mainstream” distributions of estimates, always pushing uncertainty as arguing for the high end, catastrophic warming. They should realize that in all probability if we ever do pin down things like aerosols, simple statistical arguments point to them likely having egg on their face when their arguments for the tail ends of these distributions toward warming being a bigger problem are very far removed from reality. But for now, they have the fact that we are so ignorant of the actual effects of aerosols as a convenient refuge for their extremism.
The thing that makes me wonder on that paper (I did not really read it) is how directly does Sea level translate to earth surface albedo (Fig.4 b->c). Polar caps area, sea/dry land ratio, vegetation/desert ratio, cloud cover … and the result is indistinguishable from linear?
According to Nicola Scafetta:
“The climate system is clearly characterized by a 60-year cycle. We have seen statistically compatible periods of cooling during 1880-1910, 1940-1970, 2000-(2030 ?) and warming during 1850-1880, 1910-1940, 1970-2000.”
See http://www.oarval.org/ClimateChange.htm
(Celestial Origin of the Climate Oscillations)
Another possibility?
Dr Spencer here perhaps seems to assume, as does the IPCC, that the system is linearly driven. He writes:
“To better understand those 3 factors, consider what controls how much a pot of water on the stove will warm over a short period of time. The temperature rise depends upon (1) how much you turn up the stove, or cover up the pot with a lid (“forcing”); (2) how fast the pot can lose extra heat to its surroundings as it warms, thus limiting the temperature rise (“climate sensitivity”); and (3) the depth of the water in the pot.”
His statement here of factor (2) is correct as it stands, but his use of the word “sensitivity” might be interpreted or misinterpreted to mean that the sensitivity is near enough linear as postulated by the IPCC “forcings and feedbacks” formalism. If the system is pinned by a dynamic phase boundary, then its ‘sensitivity’ will be essentially non-linear and will appear to have a “negative feedback” in the language-abusive IPCC terms, and as I think Dr Spencer may perhaps partly suspect, though I have no explicit justification to claim this based on what he has actually said.
It seems to me that if there is not such an essential non-linearity with phase pinning, then in the language-abusive terminology of the IPCC, the system might well have a “positive feedback” as in the beloved scenario of the IPCC, contrary to what I perhaps mistakenly understand of Dr Spencer’s belief. Sad to say I see very little explicit discussion of this question in what I read.
The difference is between a saucepan on the stove that has not yet come near boiling and one that is boiling. The non-boiling case more or less follows Newton’s law of cooling, which is linear, and its steady-state temperature is driven linearly by how hard you turn on the gas. The non-linear ‘quasi-boiling’ case is phase pinned and the water keeps a nearly steady temperature no matter how much you turn up the gas.
The ‘quasi-boiling’ bubbles to which I refer are the protected hot towers of deep tropical convection of Riehl and Malkus 1958. Christopher Game
I am talking about the non-boiling case. Change the analogy to heating of any object, without a phase change. Same argument holds.
Christopher, if I explicitly stated all of the conditions associated with my illustrations so that there was no chance of you misinterpreting them, by blog posts would then approach the length of your comments. 😉
As I read the IPCC “forcings and feedbacks” formalism, its real meaning is that the system, in response to a big pulse of CO2 addition, can be one of two kinds: a kind that will warm at first rapidly and then will continue to warm a lot more, but slowly, and I read this as the “positive feedback” story; or a kind that will warm at first rapidly and then soon will cool a bit back towards the pre-CO2 temperature, and I read this as the “negative feedback” story. The IPCC lives and dies on the “positive feedback” story. I do not know if this is how Dr Spencer reads it. Christopher Game
Negative feedback does not mean there will be eventual cooling after warming. It just reduces the rate of warming, and the new equilibrium temperature state..
Of course, if there are non-linear effects operating, it is theoretically possible to go in the other direction. But I have not seen any evidence of this.
I tend to think of the “feedback” as sort of like the infamous Keynesian “multiplier” (although describing economics with mathematical models is fundamentally wrong, and probably not so with a physical system like climate) as mathematically it acts to either amplify or proportionally lessen the effects of a “forcing”, so that in this sense it does not reverse the sign of the change, but determines whether it is larger or smaller than the change one would have expected if there were no feedback. Of course, in economics, if we allow for the moment the absurdity of modeling human action with formulas, the critical importance of whether the “multiplier” for government spending would be greater or less than one (analogous to positive and negative feedback) is whether the government would effectively cause the economy to lose money, or whether it would result in enough economic “boost” to cover the cost of the initial expenses plus interest. Similarly, whether the feedback is positive or negative determines whether the warming from increasing CO2 will be large or small.
Dr. Roy, you write:
“Hansen believes he knows climate sensitivity very accurately, based upon paleoclimate theories of what caused temperature changes hundreds of thousands to millions of years ago, and how large those temperature changes were. Most of Hansen’s climate sensitivity claims are based upon the Ice Ages and the Interglacial periods.”
I don’t know about you, but I cannot believe Hansen actually believes sensitivity can be estimated from the change in temperature that occurs from Ice Ages to Interglacial Periods.
As we know (and Hansen must also know), the warming of about 5 C that occurs from glacial to interglacial is driven by the large change in the Earth’s orbit relative to the Sun, which changes the angle of the incident energy, which in turn ultimately changes the distribution of the energy into the system quite dramatically. This combined with the positive feedback effect from the melting of surface ice is enough to overcome the net negative feedback on the system and cause a 5 C rise. But you can’t equate the positive feedback effect of melting ice from that of leaving maximum ice to that of minimum ice where the climate is now (and is during every interglacial period). Also, there is no such change occurring in the orbit in the current climate either, and we are very nearing the end of this interglacial period – meaning if anything the orbit has already flipped back in the direction of cooling and glaciation.
Meanwhile, Hansen et. al still cannot explain why incremental GHG ‘forcing’ will be amplified by over 400% when solar forcing is only amplified by about 60%. This is the Achilles heel of the entire AGW theory and seems to have everyone totally stumped all over the internet.
Dr Spencer writes: “Negative feedback does not mean there will be eventual cooling after warming.”
I say that the words are used so loosely and variously that one can often hardly guess what they might be intended to mean.
It is possible to have a rapid warming phase followed by a slower cooling phase, not cooling down past the starting temperature to produce eventual cooling with respect to it, but still settling to a steady state cooler than the peak of the rapid warming phase; this would be called “negative feedback” and is the most obvious interpretation of the term as used by the IPCC and is not ruled out a priori, though Dr Spencer seems to know that it will not happen, while he still believes in negative overall feedback, as do we all.
Sometimes the word “feedback” is intended to refer to the overall stability, and sometimes it is intended to refer to a component contributory moiety of the overall feedback. There is no easy way to guess what is meant on each occasion. I think Dr Spencer usually uses it to refer to overall stability, while the IPCC nearly always uses it to refer to the several component contributory moieties of the overall feedback. In some cases they are talking past each other.
The so-called “Planck response” is rapid, while for example water evaporation or cloud responses could be significantly slower. If there are several component response mechanisms with various rate coefficients, there can be various patterns of time response. The IPCC “forcings and feedbacks” formalism seems to postulate four or five “feedbacks” and this strongly suggests four or five distinct rate coefficients, with consequences.
Here are some various examples of simple hypothetical climate system dynamic response patterns:
Linear response (rate coefficient the same for positive or negative displacement), first order, one positive real rate coefficient: an explosion, ruled out by present observations. Would be called overall positive feedback or runaway effect.
Linear response, first order, one negative real rate coefficient: behaves as with Newton’s law of cooling. Would be called negative feedback, would not show overshoot to an abrupt step stimulus. Most compatible with Dr Spencer’s “heating of any object, without phase change”. Not easily compatible with the IPCC concept of feedback because it has only one rate coefficient, not four or five.
When I speak of “phase” here I refer to some kind of abrupt change of dynamical regime such as the onset of convection in a system previously free of convection. I used the term “quasi-boiling” to refer to a system pinned near the onset of some more efficient heat transport mechanism such as convection.
Linear response, second order, two different negative real rate coefficients, showing overshoot and partial cooling restoration towards but not reaching or passing the previous state. Would be called negative feedback. A likely interpretation of the IPCC concept of “negative” feedback. Not compatible with Dr Spencer’s “heating of any object, without phase change”. Rejected by Dr Spencer.
Linear response, second order, two different negative real rate coefficients, showing a rapid warming response followed by a more prolonged further warming response. Would be called “positive feedback” by the IPCC; their favoured case. Perhaps to some degree compatible with Dr Spencer’s “heating of any object, without phase change”. Perhaps the difference between Dr Spencer and the IPCC here is just as to how much more prolonged and how much further. The process here has overall negative feedback, but the IPCC finds some contributory component destabilizing moiety in the feedback which it lovingly calls “positive feedback” because it is rhetorically effective to do so.
In particular, warming causes increased water vapour column amount which the IPCC thinks tends to cause very much more prolonged and very much further warming; there is some plausibility in this. To counter this water vapour feedback contributory component moiety, for a quick settling to a steady state of the warming, the clouds would need to provide a negative contributory component moiety to the feedback effect. If such a moiety were very strong, it might lead to an overshooting response pattern. Dr Spencer is investigating the cloud effects, I think.
Non-linear response, first order, one negative real rate coefficient having different values for positive and negative displacements. Compatible with phase pinning. Rejected by Dr Spencer without stated reason.
Christopher Game
I find it interesting that Hansen bases his views on climate changes in past eras since that demonstrates that natural causes can have a huge influence on climate. Doesn’t that imply that natural factors could swamp human emissions of greenhouse gases now? Obviously this is happening because the temperature record while it shows a small increase does not agree with the predictions of AGW theory.
As for the aerosols, how can they have a huge impact on global climate when 1) aerosols tend to stay localized and are short lived so can’t be a factor in global forcing 2) satellite data shows that aerosols are only having an impact on sunlight transmission over a small region of the earths surface 3) there hasn’t been much change in this picture since 2001 (if you look at NASA satellite images on optical depth from 2001 and 2011 they are not much different).
Christopher Game- I would be most interested on what your outlook is for the climate going forward and why? Your responses are always so complete and thoughtful.
Negative feedback by itself doesn’t mean there will be cooling but what if the negative feedback is amplified by some external factor like the interaction of solar activity with cosmic rays? The estimates of impact of solar activity on climate must be severely underestimated. What caused the earth to exit the last ice age? What caused the end of the younger dryas? What caused the earth to exit the little ice age? Clearly there are some large natural forces at work that would absolutely swamp manmade CO2 levels. What melted all those 2 mile thick sheets of ice? It was not CO2 or the “PDO”. What causes the PDO? Astronomical factors have to be involved. After all the sun is *the* energy source in the solar system. If you could shut the sun off for a few days I’d like to see how effective CO2 is at trapping heat under those conditions. Probably wouldn’t last very long.
Also looking at your satellite anomaly charts it is pretty clear the data is broken in two about the 1998 El Nino. What is the warming trend prior to 1998? Just looking at the graphs it doesn’t look like there is any statistically significant warming trend. Also it almost looks like the El Nino of 1998 actually caused the jump in the anomaly that has defined temperatures since. It is not physically plausible that carbon dioxide in the atmosphere could have done that.
Sorry I am new to this debate so I apologize to jumping to other areas of interest.
Dr Spencer previously discussed the likely possibility of a a chaotic internal component of climate dynamics; mathematically this requires at least a third order system (three rate coefficients) and strong non-linearity. Now Dr Spencer is talking about what looks like a first order linear model with just one rate coefficient, and rejects a second order non-linear model. Christopher Game
Dave I agree . YOU ARE SO CORRECT! Chris makes sense also.
Dr. Spencer is trying and is making a big effort, but I think he needs to start researching the astronomical side of things.
There are many good solar scientist that make a very good case for solar, not to forget past history. Past history is still where it is at for me. Until someone can prove solar had nothing to do with past history climatic changes , I wil continue to believe that solar activity will have everything to do with future climatic changes.
The big questions are the lag times that are involved and what degree of magnitude is needed. Example how quiet and for how long in duration must solar activity be to impact the climate? How much volcanic activity is needed? How many La Ninas? How cold and long lasting PDO, does it take to really impact the climate? The AO ,how negative ,and for how long? Clouds how much of an increase ,and for how long? When does that really impact albedo? Cosmic ray increase, again how much and for how long? Earth’s magnetic field ,how much weaker and for how long? Snow cover how much more is needed to impact the climate,and albedo? Etc Etc.
The vague and undefined and unjustified use of the word “amplified” grows like a cancer, following the precedent of its toxic abuse by the IPCC. Christopher Game
Christopher, you say:
“In particular, warming causes increased water vapour column amount which the IPCC thinks tends to cause very much more prolonged and very much further warming; there is some plausibility in this. To counter this water vapour feedback contributory component moiety, for a quick settling to a steady state of the warming, the clouds would need to provide a negative contributory component moiety to the feedback effect. If such a moiety were very strong, it might lead to an overshooting response pattern. Dr Spencer is investigating the cloud effects, I think.”
I think the biggest problem with IPCC’s ‘forcings and feedbacks formalism’ is the treating of GHG ‘forcing’ differently than the response of the surface to the massive flux of energy coming into from the Sun, which already includes the lion’s share of all the feedbacks in the system from decades, centuries, etc. of solar forcing. How could it not? Calling the often referenced 1.1 C of ‘intrinsic’ warming from 2xCO2, which is derived directly from the measured response of the system to solar forcing, ‘pre-feedback’ is why so many still believe in the fantasy of the 3 C rise when it’s impossibly outside the system’s bounds.
Responding to the post of RW of July 15, 2011 at 8:25 PM.
RW writes: “Calling the often referenced 1.1 C ‘intrinsic’ warming from 2xCO2, which is derived directly from the measured response of the system to solar forcing…” No. The 1.1C is not conceivably directly measurable. It is a purely virtual mathematical artefact. That “forcing” is a power per unit area, a rate of flow of energy, the 1.1C is a steady state increment of temperature. The two quantities of are very different kinds. The relation between them requires arbitrary assumptions for a model calculation. Everyone accepts that. One common assumption is that only one “feedback” is admitted to the calculation: the “Planck response”, which is admitted to be a kind of feedback by Lacis, if I recall aright. A directly measured response would have to be influenced by all the “feedback” mechanisms. That does not mean I am defending the formalism. Christopher Game
Christopher, you say:
“RW writes: “Calling the often referenced 1.1 C ‘intrinsic’ warming from 2xCO2, which is derived directly from the measured response of the system to solar forcing…” No. The 1.1C is not conceivably directly measurable. It is a purely virtual mathematical artefact. That “forcing” is a power per unit area, a rate of flow of energy, the 1.1C is a steady state increment of temperature. The two quantities of are very different kinds. The relation between them requires arbitrary assumptions for a model calculation. Everyone accepts that. One common assumption is that only one “feedback” is admitted to the calculation: the “Planck response”, which is admitted to be a kind of feedback by Lacis, if I recall aright. A directly measured response would have to be influenced by all the “feedback” mechanisms. That does not mean I am defending the formalism.”
The 1.1 C is indeed derived directly from the measured response of the system to solar forcing. How do you think they are getting this number?
3.7 W/m^2 from 2xCO2 only provides 0.7 C of ‘direct’ warming from the Stefan-Boltzman law. The additional 0.4 C comes from adding on net transmittance to space of about 0.62 or 2.3 W/m^2 (3.7 x 0.62 = 2.3 W/m^2), which is just the post albedo radiative power from the Sun divided by the surface radiative power (240/390 = 0.62). Or just by multiplying the +3.7 W/m^2 at the surface by the reciprocal of net transmittance (1/0.62 = 1.61), which is the amount the surface has to warm up to allow the 3.7 W/m^2 to leave the system to restore equilibrium. 3.7 W/m^2 x 1.61 = +6 W/m^2, which equals about a 1.1 C rise in temperature.
Call this ‘pre-feedback’ is the problem. It really represents an upper limit since of course only the Sun truly ‘forces’ the system. All GHGs do in theory is slightly modify the solar response which then requires a different equilibrium.
Christopher, you say:
“A directly measured response would have to be influenced by all the “feedback” mechanisms.”
Yes, the solar response includes all the ‘feedback’ mechanisms in the system. How could it not? This is my point. The Sun has been ‘forcing’ the climate system for billions of years…how could the all feedbacks not have manifested themselves yet after billions of years of solar forcing?
The reciprocal of net transmittance to space is the measured response of the surface to solar forcing (390/240 = 1.63), which just means it only takes about 1.6 W/m^2 of radiative surface emission to allow 1 W/m^2 to leave the system, and this already includes the lion’s share of the all the ‘feedabacks’ in the system (convection, latent heat of water, clouds, precipitation. etc., etc.). Afterall, the 390 W/m^2 emitted at the surface is just the net surface energy flux, which is itself the net result of all the complex processes and feedbacks in the system.
I agree with your criticisms of the IPCC’s ‘forcings and feedbacks’ formalism, but I think your overlooking the most egregious thing – that is the treating of GHG ‘forcing’ in a totally different way than solar forcing, which makes absolutely no sense at all.
Christopher,
The ultimate point is if watts are watts, what’s so special about additional watts from GHG ‘forcing’ that the system will respond to them so much greater than it does to watts forcing the system from the Sun?
For what physical or logical reason would GHG ‘forcing’ be amplified by 428% (0.7 C/3 C = 4.28) when solar forcing is only amplified by 63% (0.7 C/1.1 = 0.63)?
Instead of pointing out the numerous flaws in the ‘forcings and feedbacks’ formalism, you might ask those who believe in the 3 C rise why it doesn’t take 1077 W/m^2 of surface radiative power to offset the 240 W/m^2 of incident solar power? (16.6/3.7)*240 = 1077 W/m^2. Or you might also ask them to quantify specifically how the ‘feedback’ will cause so much more change on incremental GHG ‘forcing’ and why specifically it does not on the original 98+% (240 W/m^2) from the Sun?
And this is of course assuming all of the 3.7 W/m^2 of ‘forcing’ will be incident on the surface, which is highly contestable in an of itself.
RW, you continue to muddle yourself with talk of “amplification”, undefined, where, in properly defined physical/engineering terms, there is none; and of “feedback” in vague and undefined terms. Christopher Game
Christopher,
“you continue to muddle yourself with talk of “amplification”, undefined, where, in properly defined physical/engineering terms, there is none; and of “feedback” in vague and undefined terms.”
I agree technically it’s not ‘amplification’. However, what do you want to call it? The surface net response to solar forcing? The surface or system ‘gain’? What is the proper terminology?
As far as ‘feedback’ is concerned, there is the net feedback operating on the solar response of the whole system. There are also all the individual ‘feedbacks’ (positive and negative) whose combined effects make up the net feedback operating on the system.
Let me ask you this question. There is roughly 240 W/m^2 entering the system from the Sun, 240 W/m^2 leaving the system at the TOA, and the surface emitting about 390 W/m^2. The +150 W/m^2 (390 – 240 = 150), what do you want to call this?
RW, the problem is not finding a name. It is finding a physical understanding. Christopher Game
Christopher,
Let me ask you then – the +150 W/m^2 flux at the surface, where is it coming from?
If not from the effect of GHGs and clouds as well as all the accompanying physical processes of the system, then where?
Basically, what I’m getting at here is we don’t necessarily need to know all the physical processes and feedbacks in the system because we can measure the net effect of them all.
Although the forcing from aerosols may not be known there are good reasons for thinking that the trend, at least for sulfate aersols has been flat. If the trend is flat the forcing is constant and can’t slow or accelerate global warming.
Historical Sulfur Dioxide Emissions 1850-2000: Methods and Results Pacific Northwest Laboratories report: PNNL-14537. A
reasonable guess supplied results for the 1st decade of the 21st century not covered in the report.
This report is found at:
http://www.scscertified.com/lcs/docs/SO2%20Emissions.pdf
The basic reason why sulfate emissions have been flat is that as sulfur emission controls were added in the EU and USA this countered increased coal burning. The PNNL report shows flat emissions from 1975 to 2000 when the effect of CO2 was rapidly increasing.
It is interesting that Hansen published a paper showing sulfate forcing as nearly constant.
Science 3 June 2005 Earth’s Energy Imbalance:
Confirmation and Implications Figure 1 A – look at negative forcings.
RW, you think you can take quick and clever short-cuts, but the reality is that you can’t. Christopher Game
Christopher,
You’re a difficult guy to have conversation with.
Dr. Roy,
I think there is a strong, unstated feeling by many that emission of CO2 simply has to be reduced, because it’s ‘bad’. I understand the point, we all know that oil and gas won’t last forever. On the other hand, they keep outlasting all the predictions that have been made.
We know this cannot give realistic information because the earth wasn’t created until 6,000 years ago.