I don’t agree with the ideas and conclusions presented in this lecture, but it is interesting and instructive to watch nonetheless. – Anthony
Earnest C. Watson Lecture by Professor Tapio Schneider, “Clouds and the Climate Tipping Point.” Low clouds over subtropical oceans cool Earth’s climate because they reflect most of the sunlight shining on them back to space.
It is unclear, however, how the clouds themselves change with climate; this gives rise to large uncertainties in climate change projections. Tapio Schneider’s lecture will show how advances in computing and satellite observations are enabling breakthroughs in the accuracy of climate projections. Such advances have already revealed a tipping point of the climate system: if greenhouse gas concentrations rise high enough, subtropical low clouds may melt away, triggering dramatic global warming.
Tapio Schneider is the Theodore Y. Wu Professor of Environmental Science and Engineering at Caltech in the Division of Geological and Planetary Sciences; and Jet Propulsion Laboratory Senior Research Scientist.
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Dunno. I’ll wait for Willis to chime in. I don’t know this guy. Willis I trust.
Well just look at the way he attempts to calculate “climate sensitivity to CO2” , implicitly ASSUMING that CO2 is the sole change of natural global temperature change and ignoring the BASIC PHYSICS of gas solubility being a function of temperature and , just like lying Al Gore, omits to mention the inconvenient truth that changes in CO2 lag changes in temperature in the geological proxies.
The carbon proxies he says are soil analysis of carbon isotopes, to a proxy of atmospheric CO2.
What he is calculating is the sensitivity of atm CO2 to temperature change, not the other way around.
He then uses this suggest that climate models are not sensitive enough to CO2 and goes into whether they get cloud gestimates right or not.
The FAKE assumption that not only is AGW due to CO2 but the whole of Earth’s geological history has been controlled by CO2 now seems to go without question
Exactly. “It is unclear, however, how the clouds themselves change with climate;” is the wrong way round. The whole narrative has been the wrong way round since the IPCC got underway. When we eventually learn how the climate changes with clouds, we will have started on the road to understanding.
Yep, but sadly they’ve wasted the last 40y and untold treasure trying to establish a politically motivated position instead of trying to understand the fundamental working of climate.
MAY
MIGHT
COULD
They simply “Don’t Know” and so predict Worst Case as inevitable
Don’t forget the real danger words – ‘and projections indicate that…’
Computers treat assumptions and ‘what if’ data as fact. ANY computer program containing any assumptions will NOT project accurately.
“The FAKE assumption that not only is AGW due to CO2 but the whole of Earth’s geological history has been controlled by CO2 now seems to go without question”
That assumption is not made, as it is not the case, and so it does not “go without question”.
From:
https://www.ipcc.ch/site/assets/uploads/2018/02/WG1AR5_Chapter05_FINAL.pdf
“5.3.2 Glacial–Interglacial Dynamics
5.3.2.1 Role of Carbon Dioxide in Glacial Cycles
Recent modelling work provides strong support for the important role of variations in the Earth’s orbital parameters in generating long-term climate variability. In particular, new simulations with GCMs (Carlson et al., 2012; Herrington and Poulsen, 2012) support the fundamental
premise of the Milankovitch theory that a reduction in NH summer insolation generates sufficient cooling to initiate ice sheet growth. Climate–ice sheet models with varying degrees of complexity and forced by variations in orbital parameters and reconstructed atmospheric CO2 concentrations simulate ice volume variations and other climate characteristics during the last and several previous glacial cycles consistent with paleoclimate records (Abe-Ouchi et al., 2007; Bonelli et al., 2009;Ganopolski et al., 2010) (see Figure 5.3).
There is high confidence that orbital forcing is the primary external driver of glacial cycles (Kawamura et al,. 2007; Cheng et al., 2009; Lisiecki, 2010; Huybers, 2011). However, atmospheric CO2 content plays an important internal feedback role. Orbital-scale variability in CO2 concentrations over the last several hundred thousand years covaries (Figure 5.3) with variability in proxy records including reconstructions of global ice volume (Lisiecki and Raymo, 2005), climatic conditions in central Asia (Prokopenko et al., 2006), tropical (Herbert et al., 2010) and Southern Ocean SST (Pahnke et al., 2003; Lang and Wolff, 2011), Antarctic temperature (Parrenin et al., 2013), deep-ocean temperature (Elderfield et al., 2010), biogeochemical conditions in the
North Pacific (Jaccard et al., 2010) and deep-ocean ventilation (Lisiecki et al., 2008). Such close linkages between CO2 concentration and climate variability are consistent with modelling results suggesting with high confidence that glacial–interglacial variations of CO2 and other GHGs explain a considerable fraction of glacial–interglacial climate variability in regions not directly affected by the NH continental ice sheets (Timmermann et al., 2009; Shakun et al., 2012).
In short, CO2 is a feedback generated by global temp changes caused by changes in the Earth’s orbital parameters.
Well if orbital changes are the “primary forcing” and CO2 is only consequence of that forcing , why is he not including the “primary forcing” in his simplistic formula for climate sensitivity? “Sensitivity to what ? CO2 by definition of the way he calculates it.
He is calculating that is exactly the same way as it is calculated for recent changes again under the assumption that CO2 is totally responsible for any changes in global temperature.
So thanks for the IPCC position on primary forcing of geological changes which totally backs up my point that what he is engaging in is not science but disinformation.
Anyone involved in climate modelling and holding a chair factulty position in climate study must know that. So not only is it misleading but knowingly and intentionally so. We have a word for that.
That is indeed the case but that is diametrically the opposite of what he is doing. He is dividing temp change by CO2 ratio ( ie the radiative forcing ) thus calculating , supposedly, the “sensitivity” of world temperature to changes in CO2.
If he knows, as you state, that CO2 is a response to temperature change he would do it the other way up and use change in CO2 , not the ratio.
“sensitivity of CO2 to temperature change ” = dCO2/ dT in ppm / kelvin
Quite clearly he is out to promote the idea of current “climate change” begin driven by CO2 and attempting to falsely use geological changes to “prove” CO2 is the control knob and that historic changes in natural processes can tell us how climate will respond to anthopogenic emissions.
This is the same scientific fraud which Al Gore attempted in his Convenient Untruth fictional drama. Gore may have some grounds for plausible deniabilty on the grounds he is an uneducated goof. Professor of climate engineering Schneider does not have that luxury.
Professor of Environmental Science and Engineering
Ah, so that’s where he is heading with all this. He wants to play God. That helps to understand he need for catastrophic tipping points.
Roy Spencer addresses the junk modelling on cloud tipping point.
To run a high-resolution atmosphere-ocean computer model one has to make a lot of simplifying and constraining assumptions, such as a “slab thickness” of the ocean layer constraint, making a closed system for circulations, etc. for computability… i.e. computer run-time and other stabilizing linearizations. As such they are mere computational “tricks” that are likely only valid over narrow, limited ranges. Anyone who has designed and played around with physical models of complex system understands what can be produced in silico frequently has no bearing on what happens in reality.
So when you then push the model beyond its applicable linear response range, and then see an unstable non-linear behavior arising, you should understand you’ve hit and gone beyond the boundary of what your model can tell you. This appears as a “tipping point” in the output.
But as we all know, main-stream climate science long ago discarded healthy skepticism in exchange for alarmist conclusions in order to get published.
“The first principle is that you must not fool yourself and you are the easiest person to fool.”
-Dr. Richard Feynman, Nobel Laureate Physicist
Of course today, mainstream climate science violates Dr Feynamn’s First-Principle Caution with abandon.
To actually think that clouds in a maritime air-mass with abundant warm water and convective processes will simply hit a point that clouds disappear (water vapor fails to condense into droplets under adiabatic cooling) is simply foolish. They likely just pushed the model outside its boundary limits of applicability, saw some non-linear behavior and thought this happens in the real world…
Fooled themselves if they believe that. And then they feed it pablum-like to an ignorant news media of journalists… climate porn is the real output here in this study.
They probably evaporated their 1m thick “ocean” and created 1000mm of TPW !
“To actually think that clouds in a maritime air-mass with abundant warm water and convective processes will simply hit a point that clouds disappear (water vapor fails to condense into droplets under adiabatic cooling) is simply foolish.”
Not to a meteorologist it isn’t.
It is down to the height at which convective condensation occurs.
If higher than the height of the low level inversion that lies over the ocean (when ocean colder than is normal, such that convection is capped there).
then dry convection (as below condensation level when thermals reach the stratocumulus layer) – the cloud will be broken and could dissipate.
Should the RH rise in tandem within the rising thermal, then this would not be the case, however it is thought that in a warming world evaporation will decrease due to reduction in wind strength.
Well I am a meteorologist and what you state or quote makes no sense.
Why would there be a dry adiabatic lapse rate occurring below the CCL if the surface layer is cut off from a stratocumulus base by having a temperature inversion? In such a case, there is no convective warming from the surface to generate a dry adiabatic lapse rate.
If the stratocumulus layer is to be broken in such a condition, it would be caused by the opposite of what you state. The top of the cloud layer would have dry air above it, allowing for strong radiational cooling off of the cloud tops, destabilizing the layer, and thus entraining dry air into the cloud from above and vaporizing it.
Warmers get nearly everything backwards when you look into their weak and mostly wrong assumptions.
Well I am a meteorologist and what you say makes no sense.
Why would there be a dry adiabatic lapse rate extending to the top of a temperature inversion from a stratocumulus cloud base from a colder than average ocean surface?
Below the CCL, there would be no convection generated from the ocean surface due a temperature inversion, therefore, no dry adiabatic lapse rate from the stratocumulus base to the inversion top. It would be something less to reflect no convective surface warming due to the underlying colder surface.
If this condition led to stratocumulus cloud break up of such a layer, it would come from having dry air above the cloud tops, allowing for radiational cooling of the cloud tops, destabilizing the cloud layer and mixing it with the dryer air in the layer above the clouds, thereby evaporating them.
And this process has nothing to do with global warming or “climate change”
Warmers get most everything backwards when you look into their frivolous claims.
And Anthony: I should add one more thing. Low stratus and stratocumulus clouds like the kind you are talking about seldom have sharp dry cut-offs to water vapor immediately above. Most of the time, there is ample water vapor in the layer surrounding low ocean clouds on both ends to where radiational cooling off of low cloud tops ever breaks them up, in fact, often times such a process thickens the cloud layer because the water vapor immediately above which also radiates will condense if cooled by the IR radiation process be it off the cloud top or the water vapor moist layer that surrounds it.
Such low clouds are usually broken up by approaching weather disturbances, causing increased wind an mixing from atmospheric divergence.
Chich Weisse:
“Why would there be a dry adiabatic lapse rate occurring below the CCL if the surface layer is cut off from a stratocumulus base by having a temperature inversion? In such a case, there is no convective warming from the surface to generate a dry adiabatic lapse rate.”
That’s not what I said (or at least meant).
The stratocumulus layer (maritime) is situated under an inversion (or at least a point of inflection of LR) . Correct?
There is a DALR below it (or nearly at least).
The current situation is that the CCL occurs just below the inversion, such that convected WV condenses below it and spreads out to form the Sc layer.
Yes, I know I am teaching you to suck eggs (if that saying is known in the US) but this post is for non-met as well.
Now warm the surface and keep the RH constant. The CCL level remains the same.
Warm the surface and either reduce the RH or keep the same and the CCL rises.
Should that level rise into and particularly ABOVE the inversion/inflection layer then the maritime SC with break-up of dissipate.
Any clearer?
Anthony: Yes. It is clear enough now to realize your supposition is nonsense
But for fun, I take an example that is typical in an ocean stratocumulus layer where there is only a shallow inversion capped at 2000 ft MSL.
For the sake of argument, if you’re going to assume ocean conditions, ambient air temperatures in these regions from sub tropical to polar seldom change more than 5 degF from a daily diurnal heating cycle, such as what we might expect in the extratropical Pacific ocean.
So I start with a temperature of 55 degF and a wet bulb of 53.42 degF. That gives a surface relative humidity of 83%. Now if I warm the surface during the day and assume the lapse rate remains dry adiabatic, obtaining an afternoon temperature of 60 degF, and holding the relative humidity to the same value of 83% gives me a new wet bulb of 56.89 degF. In both cases, the CCL remains unchanged at 800 ft. MSL.
But what has changed is from the new wet bulb temperature that requires an additional 1.5 gKg-1 of sea water that has to be vaporized to maintain the 83% relative humidity. In order to accomplish this, the latent heat of vaporization for water compared to the specific heat of dry air at constant pressure requires that an additional 6.61 degF of sensible heat has to come from somewhere to maintain the surface relative humidity. And therein lies the problem. Because the specific heat of water is so high compared to dry air, there is no available thermal energy to accomplish the task of maintaining surface relative humidity with only a 5 degF diurnal heating cycle and that is the only way to raise the CCL to a higher level than the 800 ft. MSL value that it is at in this example.
It is well known that climate modelers program their computer codes to hold relative humidity constant as they raise the temperature. It is part of the phony positive water vapor feedback loop the models create to artificially inject more water vapor into the system, significantly increasing IR downwelling radiation, when in reality, in most cases, there is simply not enough energy that can be used within the environmental conditions to accomplish this.
This supposition of yours is nonsense, and just one of many reasons climate modelers are clueless and whose failed models give results like this that are not reproducible in the real world.
“This supposition of yours is nonsense, and just one of many reasons climate modelers are clueless and whose failed models give results like this that are not reproducible in the real world.”
Were that the case Chuck, then I spent my entire on-the-bench forecasting career with the UKMO (including a lengthy spell forecasting the the RAF for their low flying requirements in mountainous terrain) …. doing something that was “nonsense”.
On the contrary, Your rebuttal is “nonsense”.
And what’s more your ideological bias is showing.
I showed none in my OP – it was merely basic meteorology.
Meteorological 101.
Despite your numerical reasoning, it is trivial to realise that a reduction in evaporation will result in a higher CCL.
IT is no different to forecasting the daytime formation of Cu under a capping inversion, extrapolating to the ‘over-convection’ of it spreading out under said inversion and then the breakup/dissipation of the Sc layer as the CCL rises.
Whether by a reduction of the HMR or an increase in the surface temp – the result is the same – the Normand’s point will rise.
BTW: the forecasting of Sc persistence is a major part of the job of a forecaster in the UK.
So less of the “nonsense” please.
It has NOTHING to do with “clueless” climate modellers.
It is just basic meteorology.
Should the maritime inversion over cooler SST’s remain at the same height in a warmer world AND evaporation is reduced (relative) then the CCL level of Cu and hence Sc Cugen will rise and result in breakup of dissipation of said SC sheet.
Are you still refuting that basic meteorology?
If you do, then I am at a loss to see a basis for further communication.
And Anthony, a final point of clarification so you don’t misunderstand me. If you take these hypotheticals you give, and assume a dry adiabatic lapse rate, warm the surface such as in my example by 5 degF from 55 degF to 60 degF and do not add any further water vapor into the surface air, then, you would raise the CCL by 900 ft. to 1700 ft MSL.
But the problem with this is it is a dubious assumption at best. The lower tropospheric air in these regions is stratified by the surface ocean water itself, having an enormous heat capacity and because of this, only small seasonal temperature changes in the ocean surface temperatures occur compared to land, and during the higher sun angle months, the middle troposphere becomes significantly warmer, further reducing dry adiabatic tendencies as this leads to frequent and strong inversions, so a stratocumulus layer being broken up by surface convection is a very infrequent occurrence. It is almost always broken up by increased circulation and conditional instability from approaching weather disturbances, and as we know, they bring additional clouds, but usually at higher levels and with precipitation. Not a warming scenario and not a preconceived nonsensical notion as derived by Tapio Schneider.
Anthony: You said above and I quote: “Warm the surface and either reduce the RH or keep the same and the CCL rises.”
This is nonsense and I just demonstrated it. If the relative humidity is held constant, the CCL DOES NOT rise. It will rise if surface warming occurs that is not used up evaporating more sea water, remains as sensible heat energy, and can generate a dry adiabatic lapse rate as a result.
I explained in better detail and to clarify, why creating a hypothetical like this over extratropical and polar ocean surfaces is a dubious assumption and if it happens at all, it would be extremely infrequent just because surface convection from the ocean surface is not a pronounced feature by surface warming alone. It needs the help of conditional instability that can generate dynamic lift over thermodynamic.
“me. If you take these hypotheticals you give, and assume a dry adiabatic lapse rate, warm the surface such as in my example by 5 degF from 55 degF to 60 degF and do not add any further water vapor into the surface air, then, you would raise the CCL by 900 ft. to 1700 ft MSL.”
Exactly.
That you for agreeing to the obvious.
The CCL RISES.
Which is ALL I am contending.
A rule of thumb ( observed by me with the aid of a cloud-base recorder) has it that for every 1C rise in temp, the DP remaining the same, the the CCL will rise ~ 400ft.
The contention I rebutted in my OP, was that the theory suggests (whether you agree with it or not) that in a warmer world evaporation will reduce due lighter winds.
So given that 1C TEMP rise plus (say) a 1C DP drop, then the CCL WILL BE ~ 800 higher.
And should the capping inversion remain at the same height then dry thermals will encroach the SC Cugen layer.
Disregarding all else, what is in the least contentious in that from a meteorological pov?
It has been warmer than it is now during the current interglacial. link The supposed tripping point wasn’t triggered then. There’s also no actual evidence that there is any positive feedback that is applied to CO2 caused global warming.
Even if we burn all the possible fossil fuels, we’re not going to reach a temperature we haven’t seen in the last 10,000 years. In other words, we’re not going to get to any tripping points. That is except, of course, for the tripping point that will send us back into a glacial period.
This is the major weakness of the whole CAGW edifice. Why has this so-called tipping point never been observed in the past, when CO2 levels and temperatures were much higher than today?
This time it’s different. It’s man made CO2, and that’s much worserer.
Exactly. We can all relax; there is no need for panic – even if the world is warming a lot (which it doesn’t look to be). Simply remember that “tipping points” have never existed in 4.5 billion years – so are therefore unlikely all of a sudden to become possible in 2019 A.D.
I am no scientist so cannot validly judge the science behind this theory – but I think it looks very interesting.
bingo
I also have reservations about the supposed cooling effect of clouds, related to the fact that cloud formation is a thermodynamically reversible process. Precipitation, however, is different. Evaporation/Transpiration/Precipitation provides a “heat pipe” to the radiation zone which totally bypasses the supposed Greenhouse Effect and, with associated convection, provides a massively negative feedback which essentially obviates the “Greenhouse Effect.”
The question here is ‘what is high enough’ (or, too high, if we expect the result be CAGW).
Article excerpt, to wit:
But, but, but, ……. greenhouse gas concentrations in the tropical and subtropical atmosphere are already noted for averaging 4% or greater concentrations.
maybe 100% is ‘too high’? difficult to get air at that point. 4% is ‘high enough’ imo.
I thought higher temperatures would cause more evaporation and hence more clouds. Silly me.
Yes, and that is seen every single day in the ITCZ.
Definitely. Willis did that article in 2016. https://wattsupwiththat.com/2016/01/08/how-thunderstorms-beat-the-heat/
There is a threshold SST and it is very difficult to push past that, because thunderstorms form very rapidly as temperatures approach the threshold.
Yes. The evaporation and condensation of water is what is controlling the surface temperature, not CO2. These processes also control the rate of natural emissions of CO2. The rate of change in atmospheric dew point is a much better indicator of energy fluxes than atmospheric temperature. Evaporation is an endothermic process so the temperature at the interface between water and air will tend to be at the dew point(100% humidity). This is true for clouds as well as the surface of oceans. There is not much difference between the dew point at the surface and the dew point at the bottom of clouds, so the net radiant transfer of energy from the surface to clouds will be low. Also, the cold water in clouds absorbs much of the CO2 that has been emitted and returns it to the surface in cold rain. However, when the water freezes in the top of thunder clouds, the absorbed CO2 is released into the top of the atmosphere where it can more readily radiate it’s energy directly to space.
Seems to me the clouds would just end up forming higher, because the atmosphere conditions that allowed them to form ( temp, humidity, sunlight ) would occur higher in warmer atmosphere.
They move higher at night, because of the radiation imbalance.
And also there might be a movement away from the preponderance of cumulus clouds to Altocumulus and Stratocumulus clouds. With more of these cloud types the atmosphere there could be a change in how efficiently the tropics cool.
Nature is not good at being represented by fixed parameters, as the biosphere changes nature will move to attempt to find a new equilibrium. That is the way nature goes — continually trying to find a new equilibrium as the planet chaotically and erratically changes. Rarely does nature find equilibrium, and when it does it’s only for a short time period (as a new loosely chaotic movement changes a parameter or three).
The computer model looks to have a static view of the atmosphere with the ‘cloud-top height’ and majority of cloud type being more or less fixed. If this is so then IMO, it is not realistic.
Notice the “hypothesis non-fingo” , a Newton classic : “It is unclear, however, how the clouds themselves change with climate; this gives rise to large uncertainties in climate change projections. ”
Not that clouds drive climate, are affected by GCR, Sun periodicities, no , just an occult “unclarity”.
This tradition started with Newton, the last alchemist, as biographer Maynard Keynes wrote. This is putting occult in place of science yet again, always the same imperial game.
Add in the witches brew of hysterical shrill claims , and presto the Renaissance is rolled back.
When these climate cultists say: “it is unclear how clouds change” … what they actually mean is that they had a look and it does the opposite of what is necessary for their crackpot ideas.
If you look for evidence of a tipping point, you may find that there may be one. That is not the same thing as revealing one
… low clouds may melt away, triggering dramatic global warming.
Oh, that beautiful magic word, “may”, again.
I think Tapio Schneider is suffering very serious Obelix – syndrome.
Oh I see. It’s the same old broken hypothesis, but Now With More Clouds!
The runaway feedback mechanism is a dead end. Geology says so. When are these guys going to stop denying basic science?
Professor Tapio Schneider obviously has no idea how the thermodynamic processes operate in the clouds. His naive explanations based on dubious assumptions are quite frankly nonsense. All hidden behind a raft of pretty pictures and graphs.
Nowhere does he mention the part played by the phase change of water which is the basic mechanism within a cloud structure and comprises a major contribution to the energy balances involved.
The convoluting thinking behind this lecture is a good example of why these models fail to mimic reality. GIGO comes to mind.
Hear, hear!
Oh I would guess the Professor does know a good deal about thermodynamic processes in the atmosphere, and quite well.
He’s just fallen in love with model madness. He believes his own junk model output, when healthy skepticism should inform otherwise, or he knows it is probably wrong but it presents an opportunity for his 15 minutes of fame and probably NSF grant renewals. And he is riding that pony for all the mileage he can get out of it.
Yes, repeating Al Gore’s fraudulent pretense that historical CO2 is the driving force behind temperature change when the phase lag alone strongly suggests otherwise is inexcusable from an informed scientist. That means he is knowingly misinforming and misrepresenting the historical link of temp and CO2 when clearly he knows better.
cynically jerking off the public purse for grants or throwing science under a bus to advance a political agenda seem the most likely explanation for this logical aberration.
It’s more likely that warmer water makes more clouds AS IS SEEN EVERY SINGLE DAY OVER THE TROPICAL OCEANS.
The EMERGENT (responsive to surface water warming) cloud formation keeps the waters from ever getting too warm EVERY DAY. After mid day storms that emerge from the emergent cloud formation, surface temperatures end up very significantly cooler than the temperatures that triggered the cloud formation. The storms also produce large dry air (downdraft) zones that then allow for greater IR radiation into space overnight.
Doubtless this video has found it’s way unto one of the wuwt threads: –
https://www.youtube.com/watch?v=NYoOcaqCzxo&list=PLHSoxioQtwZcog7iR-ka7EwaxB4ny8Dq-&index=16&t=0s
Pretty clear. Anything they can’t account for in the GCM’s gets auto transferred into the “It’s Our Fault” Category. Also pretty clear: – With weather at all scales being pushed around DIRECTLY by our electromagnetic connections to Sol, far beyond simple TSI as currently allowed for in the GCM’s, we are in realtime now 0bserving the consequences of the Eddy Minimum. Don’t sell your fur coat.
And as we all, as well, are in our Being and Mind – electromagnetic and ‘part of Nature’ – …consider Prayer – because with the Poles accelerating towards somewhere near Malay, with attendant “the Shields Won’t Take It, Captain” (Scotty), “Lights Out” may be far more imminent than most of us realize.
D
” if greenhouse gas concentrations rise high enough, subtropical low clouds may melt away,”
I suppose he really means “boil” away since water has already melted at 32F.
But if he says “boil”, most people would laugh at him.
“clouds may melt away”
Sure. Who would give him any grant if they may not?
Are you sure? Venus showed that clouds hold heat in over the nighttime. Venus only gets 4% of the sunlight on the ground because its clouds are so reflective, yet ground temp on Venus is 900 degrees. So I DOUBT that clouds cool a planet, and instead consider clouds as major contributors to the greenhouse effect.
Clouds do both, and Venus is a great example of that.
Imagine an ideal heat loss scenario: during the day (sun-side) high albedo clouds reflect a larger amount of sunlight than low albedo ground (I seem to remember that contra Arthur C Clarke, Venus does not have oceans), then during the night no cloud cover forms, without radiant heat from the planet reflected back to itself you’ll dump any heat picked up during the day. In an ideal heat gain state you’d have clouds that are transparent to solar radiation (so it gets to the ground), but reflective to IR (so re-radiated heat gets trapped).
Examples on earth: winter nights with clouds are warmer than clear nights (your example), summer days with clouds are cooler than clear skies (solar radiation is stopped).
Robert Beckman wrote: “Examples on earth: winter nights with clouds are warmer than clear nights (your example), summer days with clouds are cooler than clear skies (solar radiation is stopped).”
So, therefore (says I), it could be quite difficult to calculate the effect of clouds overall, right, if one were forced to start from scratch, instead of actually observing the earth?
Now, what I really want to get to here, is that earlier in this thread,
“Mortimer” wrote: “Venus only gets 4% of the sunlight on the ground,
because its clouds are so reflective, yet ground temp on Venus is 900 degrees.”
Bringing up Venus is relevant, it seems to me, even though Venus is so different from Earth,
if it helps to illustrate some basic physics points.
What bugs me about discussions of Venus surface temperature, is that it often seems to me we are missing one of the most basic physics reasons why we would get a hot temperature down deep in a reasonably dense atmosphere (such as Earth’s atmosphere, Venus atmosphere, the atmosphere of Saturn’s moon Titan, or even the atmospheres of the gas giants as such). As it happens, there is a special mechanism, usually called “dry adiabatic lapse rate” that seemingly can explain the tendency for atmospheres to get hotter with depth, under some broad range of circumstances, *without* necessarily having to worry overmuch about IR properties of gases (at least not for just determining the gradient with depth anyway).
Now apologies in advance for throwing in a somewhat “calculus” looking web page, but the following University of Texas link sets this out much better than I ever could, I’m sure, see “The Adiabatic Atmosphere” at:
http://farside.ph.utexas.edu/teaching/sm1/lectures/node56.html
Now, the above article is oriented to describing how the “dry lapse rate” in temperature can be derived for the earth, also with some discussion of how to include moisture related effects (applying this to other planets would be a slightly different discussion, but with the basic principles being very much the same). The key quote from this, as to basic principles, is:
“Imagine a packet of air which is being swirled around in the atmosphere. We would expect it to always remain at the same pressure as its surroundings, otherwise it would be mechanically unstable. It is also plausible that the packet moves around too quickly to effectively exchange heat with its surroundings, since air is very a poor heat conductor, and heat flow is consequently quite a slow process. So, to a first approximation, the air in the packet is adiabatic. In a steady-state atmosphere, we expect that as the packet moves upwards, expands due to the reduced pressure, and cools adiabatically, its temperature always remains the same as that of its immediate surroundings.”
So there in a nutshell, is a good reason to think that the surface of Venus is going to be *very* hot, due to the effect of an atmosphere some ninety times as dense as earth’s, just *bearing down* on the surface with the full force of the resulting adiabatic convection effect!
Surely this has nothing necessarily much to do with the fact of very little sunlight reaching Venus surface?
Presumably then, there is some layer in the “heat engine” of Venus atmosphere where the sunlight *does* do a lot to determine temperature *there*,
but that “sun determined” level presumably could be quite high up above the surface as such.
The relevance of this to the earth, it seems to me, is that quite a lot of our own surface warming could be adiabatic in origin,with the lower level clouds not interfering with the ability of the sun to “set” a temperature somewhere in the mid troposphere.From there, things just get warmer the farther you go down.
In a way then, it’s almost a given that planets with some sort of quite heavy burden of “air” on them are going to have warm surfaces or warm layers lower down! I mean, why should everything depend on the amount of sunlight hitting the surface as such?
It is the Atmpospheric Pressure!
Or, pressure driving convection in a compressible fluid (i.e., a gas).
When I see tipping points mentioned, the discussion usually seems to start with the premise that there would be only one.
I see no reason why there couldn’t be many, each potentially causing a transition between closely related climate ‘micro-states’, actually helping to keep the climate in check and preventing any runaway thermogeddon so beloved by the alarmists.
“… subtropical low clouds may melt away, triggering dramatic global warming.”
And off course, no negative-feedback from evaporation and clouds formation … all the warming induced cloud formation will certainly hide under the oceans or migrate to Mars because climate change.
I wonder when the devastating tipping point triggered in Tapio’s brain.
I hadn’t time this morning to watch the entire video, but what I did watch was, I thought, quite interesting. The discussion of uncertainties with clouds was very interesting. I noticed two things I would object to immediately. The professor makes his rough estimate of delta CO2 by pointing to the upper reaches of proxy measurements of CO2 in the Eocene. The graph shows a tremendous range of CO2 estimates during the Eocene, though. No error bars shown at all. I’d say we don’t know what delta CO2 actually is over the time period in question. However, he assumes for purposes of his BOE estimate of sensitivity that CO2 is the sole driver of climate. Yet the map of the arctic shows how different the geography was. To what degree did this specific geography contribute to the times? How large is Delta temperature? The proxies all map closely to one another, but what are the error bars here?
Finally, by showing crocodiles in the Arctic, we are pretty sure the Arctic was warm. It was a lot warmer 8,000 years ago than it is now too. I am willing to bet the tropics were little different than today. Other than losing sea ice, is a warm Arctic a terrible thing? If sea level rises, it will do so over hundreds of years, and we can replace assets near coastlines over hundreds of years stepping back from the coast as we do so. We have to replace assets anyway. They wear out.
So many scientific people view changing climate as a pure scientific exercise, but it is not. It is just as much, perhaps more, an economic and political exercise. In graduate school I knew first-rate scientists, many of them were economic and political imbeciles. Completely impractical–prone to hubris and narrow thinking. Heaven help us if they become a dogmatic scientific priesthood.
“If sea level rises, it will do so over hundreds of years, and we can replace assets near coastlines over hundreds of years stepping back from the coast as we do so. ”
Which is what civilizations have done, always. Alarmists seem to think we’ve lost the ability to build things.
Buildings are temporary, and none are more so than places built close to oceans.
If you are within the historic storm surge zone, the dwelling you are living or working in is temporary.
This includes every place that might possibly be swamped due to rising seas.
Storm frequency dwarfs sea level rise as a limiting factor for near shore structures.
Building out of expensive real estate that is only a few feet above the sea continues to accelerate all around the world.
Even more tellingly, any time a storm wrecks buildings near oceans, or floods destroy buildings near rivers, they are rebuilt as rapidly as possible.
Wait and see what happens next time a place like New Orleans, or N.O. itself, is flooded or knocked down by water: If anyone is calling for the entire place to be condemned and the rebuild to take place on higher land, they will be ignore and even vilified, and typically by the same sort of people who are alarmists.
Lots of people are making lots of noise, but all they really want to do is raise taxes or force spending on some scheme which profits some particular group of people.
There are people in California who are pushing for condemning shoreline real estate, even though the sea level along the coast of that state has barely budged in over 100 years. Just wait and see how this plays out for a clue re what will happen when push comes to shove and rich people are about to have their homes condemned over nothing but hot air blathering and alarmist lies.
Almost all of the California coastline is near-vertical: A few feet of rocky or sandy beach in an inlet curve, then shear rocky cliffs up 45-65 feet, then the inland coastal road and another hillside rise to the top.
Very, very little (LA basin of Long Beach (hence the name!) and San Diego harbors for example) are “flat” coming inland. Even the LAX airport (its runways end right at the sea) is on a “cliff” 128 feet up above the narrow beach itself.
Internally, only the many square miles around the San Francisco Bay are “flat” – our house in Vallejo at the base of the Napa River was less than 15 feet above high tide level.
By the way, would that California measure for “shoreline” restrictions apply “up the river” towards Napa Valley, Sacramento, San Jose, SFO airport, San Francisco itself, Santa Rosa …. Let’s plow the Napa Valley to “preserve it”!
“Heaven help us if they become a dogmatic scientific priesthood.”
If?
It seems you have not been keeping up with current events.
This is exactly what has occurred.
But Heaven will not help us, we are going to have to do that ourselves.
I have searched the geological record over the past couple of billion years, and see no evidence of a “tipping point”. Whatever are these people talking aboug.
They are just spinning fantasy.
They make stuff up, pretend their ideas represent reality, and tell us all we need to believe them, or else!
In a nutshell, that is the entire story.
The Malinkovitch orbital changes of high latitude insolation forcings became a dominant climate forcing effect, a “tipping point” had been reached 2.6 Million years ago (Mya).
The Earth climate system clearly fell into a new Climate state during the Late Pliocene to Pleistocene transition 2.6 Mya. We call the Quaternary period of cyclic glaciations.
Full ice shield formation in Antarctica was in-place 3 Mya, the Panama Seaway was fully closed ending equatorial warm water flow from the Atlantic into the Pacific, altering Pacific cold water upwelling in the eastern Pacific. Greenland became fully glaciated.
The Ice Ages (glaciations) began, and cycled rapidly in 41 Kyr periods. That went on for ~1.5 million years, until a Mid-Pliestocene transition to 110 Kyr periods about 1.1 Mya.
Tipping points do occur in non-linear systems. But all the paleo evidence is atmospheric [CO2] is not causal in the dominant control of Earth’s climate, as [CO2] follows global temperature in the paleo climate records.
You must be careful about being rational down at the pub!
The tipping point is the other way. As the earth cools the moisture in the atmosphere snows out at the poles and THEN the tropical clouds melt away. CO2 also ‘melts away’ dissolving in the cooling seawater! Now there’s a theory you can get your teeth into, Doc.
Joanie Mitchell time again. Models just don’t know clouds, and water vapor is the primary greenhouse gas.
Right off the bat, he gives a long-winded whinge about AC and why he needs it, even though it might make him “intolerant” or “soft”, because “climate change”, of course. Soft in the head maybe. The biggest reason AC is used more today than say 50 or 60 years ago is that living standards are higher, and more people can afford it, plus, UHI today is more of a factor.
It is also cheaper to buy an AC unit than it used to be, and they are more efficient, and hence less costly to operate.
UHI may affect a larger amount of surface area, but within the places that are subjected to UHI, it has not changed much.
The thermal properties of concrete and masonry are the same as ever.
In many places, there may be some diminishment of the UHI effect, such as places where railroads have been turned into greenways, or where tree planting programs in inner cities have lessened the desert effect of a zero vegetation environment. Etc.
If the climate were as sensitive to warming as climate nutters like this keep saying … then why did the warming at the end of the ice-age come to an end? According to their pathetic assertions, once the world starts warming at the end of the ice-age, it would just keep warming and warming and warming and until the world were red hot.
How do we know their assertions are the crazed rantings of a climate cult? ….because if they were right, then they wouldn’t be around to make these crazy assertions because we’d all have fried long ago.
Indeed if these bozos understood what they were looking at they would come to the other conclusion: that the climate is extremely insensitive to increases in CO2 in the interglacial (the period we have now).
Ahem, cough, cough.
One popular geoengineering strategy proposed for countering imaginary global warming/climate change is reducing solar heating by increasing the earth’s albedo.
This increase is accomplished by various physical methods, e.g. injecting reflective aerosols into the atmosphere, spraying water vapor into the air to enhance marine cloud brightening, spreading shiny glass spheres around the poles with the goal of more reflection thereby reducing the net amount of solar energy absorbed by the atmosphere and surface and cooling the earth.
More albedo and the earth cools.
Less albedo and the earth warms.
No atmosphere means no water vapor or clouds, ice, snow, vegetation, oceans and near zero albedo.
Zero albedo and much like the moon the earth bakes in that 394 K, 250 F solar wind.
These geoengineering plans rely on the atmosphere cooling the earth and expose the error and delusion of greenhouse theory which says the atmosphere warms the earth and with no atmosphere the earth becomes a -430 F frozen ball of ice.
A failure of greenhouse theory means no CO2 global warming and no man caused or cured climate change.
Nick Schroeder, BSME CU ’78, CO PE 22774
Nick, you were good up the 394K baking part. Earth would get warmer as a result of absorbing the Sun’s radiation, which has much more “heat” in it than the “solar wind”.
If someone makes the rather Polyanna assumption that the Earth has an Albedo of 0.3, you can show that the Earth is about 33C warmer due to Greenhouse gases than it would be without those greenhouse gases. But the Albedo of clouds varies widely around 0.6, and the planet is 1/2 covered by cloud, 70% ocean at albedo about .05, so actually cloud cover controls the Albedo of the planet. And the amount of planet cloud cover is very likely primarily controlled by the temperature of the ocean surface.
So you are correct in the sense that without water vapour, there would be no clouds and the planet would be warmer as a result of decreased Albedo. However there is no failure of greenhouse gas theory here. There likely is a failure of cloud cover albedo parameters in the computer models.
DMac,
Posted a different reply further down the thread.
However, in some other words.
1. 288 K – 255 K = 33 C warmer with the atmosphere is rubbish. 288 K is a WAG pulled from WMO’s butt. NOAA/Trenberth use 289 K. UCLA Diviner mission uses 295 K. The 255 K is a theoretical S-B “what if” temperature calculation for a ToA average 240 W/m^2 (w/ atmosphere!!) ASR/OLR balance (1,368/4 *.7) based on a 30% albedo.
By definition “no atmosphere” includes no clouds, no water vapor, no oceans, no vegetation, no ice, no snow and an albedo perhaps much like the moon’s 0.11. 70% of the lit side would always be above freezing, 100 % coverage realized over the annual seasonal tilt, not that it matters since there would be no water to freeze.
Without the atmosphere the earth gets 20% to 40% more kJ/h depending on its naked albedo from a solar wind 20 to 30 C hotter not 33 C colder.
The atmosphere is not a greenhouse but like that reflective panel behind a car’s windshield.
Instead the idiots want to install more solar electric panels, absorbing even more of the sun’s energy, which degrades to heat after and even during use. Cost ineffective and damaging to their intent. Hopeless!
The albedo of the moon is 0.12.
IOW, 12 of incident radiation is reflected from the surface.
What the hell is this zero albedo crap you are asserting?
Only an imaginary surface has zero albedo.
Black hole? 😎
Sorry, 12% it should say.