Current trend of “global warming” isn’t enough to get there, says MIT scientist.
How Earth sheds heat into space
New insights into the role of water vapor may help researchers predict how the planet will respond to warming.
Just as an oven gives off more heat to the surrounding kitchen as its internal temperature rises, the Earth sheds more heat into space as its surface warms up. Since the 1950s, scientists have observed a surprisingly straightforward, linear relationship between the Earth’s surface temperature and its outgoing heat.
But the Earth is an incredibly messy system, with many complicated, interacting parts that can affect this process. Scientists have thus found it difficult to explain why this relationship between surface temperature and outgoing heat is so simple and linear. Finding an explanation could help climate scientists model the effects of climate change.
Now scientists from MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS) have found the answer, along with a prediction for when this linear relationship will break down.
They observed that Earth emits heat to space from the planet’s surface as well as from the atmosphere. As both heat up, say by the addition of carbon dioxide, the air holds more water vapor, which in turn acts to trap more heat in the atmosphere. This strengthening of Earth’s greenhouse effect is known as water vapor feedback. Crucially, the team found that the water vapor feedback is just sufficient to cancel out the rate at which the warmer atmosphere emits more heat into space.
The overall change in Earth’s emitted heat thus only depends on the surface. In turn, the emission of heat from Earth’s surface to space is a simple function of temperature, leading to to the observed linear relationship.
Their findings, which appear today in the Proceedings of the National Academy of Sciences, may also help to explain how extreme, hothouse climates in Earth’s ancient past unfolded. The paper’s co-authors are EAPS postdoc Daniel Koll and Tim Cronin, the Kerr-McGee Career Development Assistant Professor in EAPS.
A window for heat
In their search for an explanation, the team built a radiation code — essentially, a model of the Earth and how it emits heat, or infrared radiation, into space. The code simulates the Earth as a vertical column, starting from the ground, up through the atmosphere, and finally into space. Koll can input a surface temperature into the column, and the code calculates the amount of radiation that escapes through the entire column and into space.
The team can then turn the temperature knob up and down to see how different surface temperatures would affect the outgoing heat. When they plotted their data, they observed a straight line — a linear relationship between surface temperature and outgoing heat, in line with many previous works, and over a range of 60 kelvins, or 108 degrees Fahrenheit.
“So the radiation code gave us what Earth actually does,” Koll says. “Then I started digging into this code, which is a lump of physics smashed together, to see which of these physics is actually responsible for this relationship.”
To do this, the team programmed into their code various effects in the atmosphere, such as convection, and humidity, or water vapor, and turned these knobs up and down to see how they in turn would affect the Earth’s outgoing infrared radiation.
“We needed to break up the whole spectrum of infrared radiation into about 350,000 spectral intervals, because not all infrared is equal,” Koll says.
He explains that, while water vapor does absorb heat, or infrared radiation, it doesn’t absorb it indiscriminately, but at wavelengths that are incredibly specific, so much so that the team had to split the infrared spectrum into 350,000 wavelengths just to see exactly which wavelengths were absorbed by water vapor.
In the end, the researchers observed that as the Earth’s surface temperature gets hotter, it essentially wants to shed more heat into space. But at the same time, water vapor builds up, and acts to absorb and trap heat at certain wavelengths, creating a greenhouse effect that prevents a fraction of heat from escaping.
“It’s like there’s a window, through which a river of radiation can flow to space,” Koll says. “The river flows faster and faster as you make things hotter, but the window gets smaller, because the greenhouse effect is trapping a lot of that radiation and preventing it from escaping.”
Koll says this greenhouse effect explains why the heat that does escape into space is directly related to the surface temperature, as the increase in heat emitted by the atmosphere is cancelled out by the increased absorption from water vapor.
Tipping towards Venus
The team found this linear relationship breaks down when Earth’s global average surface temperatures go much beyond 300 K, or 80 F. In such a scenario, it would be much more difficult for the Earth to shed heat at roughly the same rate as its surface warms. For now, that number is hovering around 285 K, or 53 F.
“It means we’re still good now, but if the Earth becomes much hotter, then we could be in for a nonlinear world, where stuff could get much more complicated,” Koll says.
To give an idea of what such a nonlinear world might look like, he invokes Venus — a planet that many scientists believe started out as a world similar to Earth, though much closer to the sun.
“Some time in the past, we think its atmosphere had a lot of water vapor, and the greenhouse effect would’ve become so strong that this window region closed off, and nothing could get out anymore, and then you get runaway heating,” Koll says.
“In which case the whole planet gets so hot that oceans start to boil off, nasty things start to happen, and you transform from an Earth-like world to what Venus is today.”
For Earth, Koll calculates that such a runaway effect wouldn’t kick in until global average temperatures reach about 340 K, or 152 F.
Global warming alone is insufficient to cause such warming, but other climatic changes, such as Earth’s warming over billions of years due to the sun’s natural evolution, could push Earth towards this limit, “at which point, we would turn into Venus.”
Koll says the team’s results may help to improve climate model predictions. They also may be useful in understanding how ancient hot climates on Earth unfolded.
“If you were living on Earth 60 million years ago, it was a much hotter, wacky world, with no ice at the pole caps, and palm trees and crocodiles in what’s now Wyoming,” Koll says. “One of the things we show is, once you push to really hot climates like that, which we know happened in the past, things get much more complicated.”
This research was funded, in part, by the National Science Foundation, and the James S. McDonnell Foundation.
NOTE: Try as I might, I could not locate the paper by press time. In its press release, MIT failed to include a link to the paper, DOI, or title of paper….anything that could possibly help find it at PNAS. Journalism 101 failure.
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Its all very interesting, but surly a good look at Earths past climate history would be a far more accuraate way to say how things actually work.
Remember we are a water planet, so we would have to boil off the vast ocean s b efore we got to a Venus like state.
MJE
And each g of water takes 512 cal of thermal energy to evaporate **without** changing temperature. Considering that the average temperature of the oceans is (all the oceans not just the surface) is about 9deg C there ain’t no tipping point anywhere in anyone’s lifetime (nor in our great-great-great-great etc grand children’s lifetime)
Where did you get the 9C figure?
Surely there’s no need to be surly.
Didn’t Roy Spencer make a similar simple 1D radiation model and post it on his blog a couple of years or so ago?
They still can’t give the simple differential by which spectral phenomenon traps higher energy density on the side away from the source .
All these decades and NO simple testable quantitative equation for the basic phenomenon .
Bob Armstrong wrote, “They still can’t give the simple differential by which spectral phenomenon traps higher energy density on the side away from the source.”
It doesn’t, Bob. The source of most LWIR in the atmosphere is the Earth.
That surprises many people, who are used to thinking of the Sun as the source of all radiant energy. But it isn’t. The Earth emits about as much radiant energy as it absorbs from the Sun.
The difference is that the incoming radiation and outgoing radiation are at different wavelengths. The Earth’s emitted energy is almost entirely at far Infrared (LWIR) & longer wavelengths. The Sun’s incoming radiation is in the near IR, visible light, and shorter wavelengths.
So if there’s a dye/colorant in the atmosphere which is transparent to the incoming wavelengths (from the Sun), but absorbs some of the outgoing wavelengths (from the Earth), adding that colorant to the atmosphere has a differential effect, preventing the escape of energy which would otherwise have been lost to space, and thus warming the Earth.
We (somewhat inaccurately) call those colorants “greenhouse gases.” That’s a poor name, because they don’t work the way that greenhouses work, but they do cause warming.
Learn more here:
http://sealevel.info/learnmore.html
Please show us your equations by which the bottom of atmosphere temperatures of planets are hotter than the radiative equilibrium determined by their absorptivityemissivity spectrum as seen from outside .
Simply the differential which “traps” a higher energy density on the side away from the source will do .
Bob Armstrong wrote, “They still can’t give the simple differential by which spectral phenomenon traps higher energy density on the side away from the source.”
I replied, “It doesn’t, Bob. The source of most LWIR in the atmosphere is the Earth.”
And Bob replied, “Please show us… the differential which “traps” a higher energy density on the side away from the source…”
I just told you, Bob: GHGs in the atmosphere do not trap energy “on the side away from the source.”
Why do you keep writing that? Did you not read what I wrote?
If you’re an object in the Earth’s atmosphere (e.g., an airplane or a GHG molecule), a majority of the LWIR photons that pass your way come from below, not above. The Earth is the original emitter of the LWIR radiation, not the Sun.
The energy originally comes from the Sun, but it is transported to the Earth’s surface in the form of short-wavelength radiation, which the GHGs in the Earth’s atmosphere do not absorb. That short-wavelength radiation (near IR and shorter) is absorbed by the surface of the planet, heating it. The surface, in turn, radiates that energy away, as long-wavelength radiation (mostly LWIR).
If there were no GHGs (or other obstructions, like clouds) in the atmosphere, the LWIR would radiate straight from the Earth’s surface to outer space, cooling the surface. But GHGs prevent some of that LWIR from escaping. They intercept it on the way out, heating the bulk atmosphere. The warmer atmosphere, because it contains GHGs, emits LWIR in all directions. Some of that radiation escapes to outer space, but some of it is absorbed by the Earth’s surface, heating it.
That “downwelling IR” from the GHGs in the Earth’s atmosphere is measurable, BTW.
So if you’re an object or molecule in the atmosphere, most of the short-wavelength radiation you encounter will come from above, but most of the LWIR you encounter will come from below.
If you’re very near the Earth’s surface, looking down, the radiation spectrum you see coming from the Earth’s surface will be similar to a blackbody spectrum at the temperature of the surface.
The average temperature of the Earth’s surface is about 15 C = 59 F = 288.15 K. (In the tropics, it’s warmer than average: about 300K.)
So if you’re in the atmosphere, looking down from just a few inches above the surface, the radiation spectrum you see will be a nice smooth graybody curve, peaking around 17 µm. But if your altitude increases, the spectrum develops “gaps” in bands where GHGs absorb, and if you look down at the atmosphere from above, from an orbital satellite, it looks something like this:
This is a quote from Prof. Robert G. Brown, a Duke U. Physics professor, from a private email conversation:
*—–( begin excerpt )—–*
_”…I got tired of people claiming that thermal equilibrium in an air column include the adiabatic lapse rate (a pure consequence of convective transport in a heated system that is never in equilibrium) and other stuff like that that let them claim that “gravity” is why the atmosphere is warmer at the bottom than at the top, not any form of radiation trapping. You could walk them through the really simple (well, to me:-) example of surrounding a heated sphere with a thin perfect absorber emitter layer, leading to a bone simple increase of 1.19 x its previous equilibrium/greybody temperature for the given rate of heat input and all they’d do is parrot thermodynamics that heat only flows from hot to cold (which is true, and which is exactly why the heated body in the middle of the absorbing layer has to heat up!) …half of those people wanted to claim that there has been no warming of the planet at all, that carbon dioxide is completely unimportant, that CO2 COOLS the planet… cognitive dissonance is much too strong….”_
*—–( end excerpt )—–*
Multi-layer insulation (“MLI”) is a nice “real world” application of the mechanism illustrated by his example of a heated sphere surrounded by a thin perfect absorber/emitter layer:
https://en.wikipedia.org/wiki/Multi-layer_insulation
GHGs in the atmosphere work like that, albeit only for certain LWIR wavelengths, and the GHG layer is not “thin.”
Still, the principle is the same: the surface of the Earth is heated by sunlight, and as a result emits LWIR radiation toward outer space. If there’s a GHG in the atmosphere which absorbs LWIR radiation, preventing it from escaping, and also emitting LWIR, some of which is absorbed by the Earth’s surface, the result will be that the surface of the Earth warms.
As the surface warms, its rate of LWIR radiation emission increases. The warming process will continue until the rate at which radiative energy escapes the Earth is as great as the rate at which radiation from the Sun is absorbed by the Earth.
Note that Prof. Brown is not a climate alarmist. He is outspokenly skeptical of climate alarmism. That is because the best evidence is that anthropogenic greenhouse warming is modest and benign, not because it is zero.
Dave,
Nice to see someone who really knows his radiation physics and furthermore bothers to demonstrate its truth with a practical example – satellite insulation, which cannot be contradicted because it actually exists and works!
Keep up the good work…
David
“The warmer atmosphere, because it contains GHGs, emits LWIR in all directions. Some of that radiation escapes to outer space, but some of it is absorbed by the Earth’s surface, heating it.”
The warmer atmosphere got warmer, because the surface that warmed it is even warmer than the warmer atmosphere that the even warmer surface warmed. Thus, that warmer-atmosphere energy is LOWER than the even-warmer surface energy. Hence, the lower energy of the warmer atmosphere cannot possibly increase the energy of the even warmer surface, whose energy ALREADY exceeds that of the “warmer atmosphere”.
How did the atmosphere get warmer? The higher energy of the surface increased the atmosphere’s energy. Yes, the atmosphere’s energy is now higher, but NOT AS HIGH as the energy of the surface that warmed it. Again, then, there is no way that the lower-energy atmosphere could be absorbed by the ALREADY WARMER surface to cause further heating of the surface.
Excellent explanation.
Just in case providing some arithmetic will help your interlocutor understand, I’ll add here a hypothetical I’ve used before.
Because of convection and conduction, an altitude layer in the real atmosphere can emit more or less radiation than it absorbs. To keep things simple, though, let’s imagine that there’s no convection or conduction: at equilibrium each layer has to emit all it absorbs. Also, although the real atmosphere absorbs some solar radiation directly, the atmosphere in our hypothetical is completely transparent to solar radiation; it absorbs radiation only from the surface and other layers.
The following radiation quantities are consistent with those assumptions but show that the surface emits 2.2 W/m^2 for every 1 W/m^2 it absorbs from the sun. And only that 1 W/m^2 escapes back to space. Yet the emissions equal the absorptions: no energy is created or destroyed.
Total
Absorbed from: Surface L.Atm U.Atm Space Absorbed
Absorbed by:
Surface 0.0000 1.0500 0.1500 1.0000 || 2.2000
Lower Atmosphere 1.6500 0.0000 0.4500 0.0000 || 2.1000
Upper Atmosphere 0.4125 0.7875 0.0000 0.0000 || 1.2000
Space 0.1375 0.2625 0.6000 0.0000 || 1.0000
————————————————
Total Emitted: 2.2000 2.1000 1.2000 1.0000
Dave B’s quoting of Prof. Brown’s is troubling:
“You could walk them through the really simple (well, to me:-) example of surrounding a heated sphere with a thin perfect absorber emitter layer, leading to a bone simple increase of 1.19 x its previous equilibrium/greybody temperature for the given rate of heat input …”
1.19 x ? How is that possible? — I thought that the thin layer would heat up to the same temperature as the sphere it surrounds, and so the whole system would be at the same temperature, NOT one part of the system 1.19 x greater temperature.
… and then Dave B goes on to say:
“Multi-layer insulation (“MLI”) is a nice “real world” application of the mechanism illustrated by his example of a heated sphere surrounded by a thin perfect absorber/emitter layer:”
From my understanding, no it is NOT, because Multi-layer Insulation is a REFLECTOR, and reflection is a different animal than emission. CO2 does NOT reflect radiation.
Robert Kernodle: “1.19 x ? How is that possible? — I thought that the thin layer would heat up to the same temperature as the sphere it surrounds, and so the whole system would be at the same temperature, NOT one part of the system 1.19 x greater temperature.”
I haven’t worked out Dr. Brown’s example, but I had intended my hypothetical above to be helpful with questions like yours. (The table didn’t come out so well, so I’ll try it again below.)
Each atmosphere layer in this (no-convection, no-conduction, lumped-parameter) hypothetical absorbs ¾ of the radiation it receives, and it emits all the radiation it absorbs. Also, 1 W/m^2 comes from space and the same amount is returned to space, but the surface emits 2.2 W/m^2. If you go through the arithmetic you can confirm this. If you so change it that each atmosphere layer absorbs all the radiation it receives, then the surface will emit 3.0 W/m^2.
The point is that no energy is created or destroyed, yet the surface emits 2.2 times as much power as the system receives from space (the sun). Each atmospheric layer receives more, too.
By your logic it is clearly trivial to build a perpetual heat engine . The more layers you divide your sequence of filters into the greater the heat “trapped” Surely it should be totally trivial to present a quantitative demonstration of it . Perhaps you should make a YouTube demo and win the first Ritchie Prize .
I still would like to see the equation which does the trapping . A simple observation which counters the notion that ever increasing heat can be trapped between a surface and a series of spectral filters on the side away from the source is that each successively hotter layer radiating in all directions is radiating more back in the direction from which its heat came than is being radiated towards it .
But in all these decades , you’d think you would be able to find definitive equations quantifying the trapping as simple and straightforward as those showing the balance between gravitational and thermal energy which is so ubiquitous .
Thank you, David Cosserat, and (especially!) thank you, Joe Born.
Robert, you wrote, “the lower energy of the warmer atmosphere cannot possibly increase the energy of the even warmer surface, whose energy ALREADY exceeds that of the “warmer atmosphere”.”
That’s an incorrect statement. (It’s the “slayer” error.) Cooler things do help warmer things stay or become warmer than they otherwise would be, all the time.
Don’t you wear a coat on a chilly day? That coat makes you warmer than you otherwise would be, even if no part of the coat is as warm as your body temperature.
The flow of energy , which computes linearly is simpler to deal with than temperature .
The law is real simple .
dE%dt = E0 – E1
where E0 and E1 are 2 energy densities . Thus the closer E0 and E1 are ( in terms of corresponding temperatures ) the slower the flow .
But , again , it must be pointed out that planets are heated from the outside and putting a coat on a corpse doesn’t warm the corpse any hotter than that determined by the color of the coat and the color of the heat source .
Bob Armstrong:
“By your logic it is clearly trivial to build a perpetual heat engine.”
“[E]ach successively hotter layer radiating in all directions is radiating more back in the direction from which its heat came than is being radiated towards it.”
I’m sorry, but I don’t follow either statement.
A perpetual heat engine has to create or destroy energy. Where in the numbers I provided is energy being created or destroyed? Again, each layer is emitting only what it is absorbing.
As to “each successively hotter layer,” let’s take the lower atmospheric layer. It emits only 1.05 W/m^2 back in the direction of the surface (“from where its heat came”), which is less than the 2.2 W/m^2 that “is being radiated towards it” by the surface. You may object that its heat ultimately came from the other direction, i.e., from space, but that’s not the atmosphere’s point of view. In our hypothetical the atmosphere is perfectly transparent to the (call it short-wave) radiation from space. The atmospheric layer doesn’t know about the power from space; all it knows is the power it receives from the surface and the other layer.
As to equations, I’m not sure what you mean, and anyway I doubt that my providing any would advance the discussion. My parish tutors inner-city kids, and from that experience I know that failure to master arithmetic first causes problems in comprehending algebra. So we should wait until you’ve mastered the arithmetic in the table.
Anyway, deriving the equations for the distributed-parameter version, where the number of layers is infinite, would require calculus. And, frankly, I can’t at the moment think of a way to do that elegantly.
The Sun supplies a radiant energy density to Venus’s orbit of about 2613. w%m^2 . ( I like to think in terms of energy density because it’s convertible by dividing by a lightsecond and the thermal energy at the bottom of an atmosphere has no direction . )
Spread over the sphere that’s
2614. 4. 2_f %f |>| 653.5 | w%m^2
It’s bottom of atmosphere temperature is reported to be ~ 735. , an energy density of
735. _f T>Psb |>| 16548.6 | w%m^2
That’s a ratio of about
16548.6 653.5 2_f %f |>| 25.3
So where does the 25 times greater energy density at the surface come from ? you are claiming its from some stack of spectral filters . Please show us your equations because surely with our technology we can emulate such a filter stack and make our perpetual heat engine .
( Forgive cutting and pasting the raw 4th.CoSy which is RPN and has to convert values directly off the x86 float stack . )
Note , TiNOX , http://cosy.com/Science/AGWpptTiNOX.jpg , comes close , but that’s with an absorptivity over the solar spectrum of about 0.95 , not Venus’s ~ 0.1 .
Mr. Armstrong:
It appears that we’re destined not to join issue, so it would be a waste of your time for me to respond further.
“If you’re an object in the Earth’s atmosphere (e.g., an airplane or a GHG molecule), a majority of the LWIR photons that pass your way come from below, not above.”
You suffer from the most common misunderstanding of the greenhouse effect, that it is a radiative effect. It isn’t, it is very largely convective. Your theoretical GHG molecule will indeed receive very slightly more LWIR from below than from above or sideways, but most of the heat moving upward is rising warm air and in particular latent heat in the form of rising water molecules.
“preventing the escape of energy”
Energy of what ?
they flip knobs up and down? when were they born?
nevertheless, kudos for packing the planet into a tube.
And what happens when the water vapor absorbs IR? It gets hotter, right? What happens to hotter water vapor? It rises in altitude and experiences an adiabatic lapse rate, right? What happens when it hits 0 degrees C? Shucks the present temperature in the ’76 std. atmosphere at 20 km is a tad over 200 degrees K, way below freezing. Well, where I come from, that implies that the water vapor dumps heat and freezes pretty hard.
Sounds to me like these guys have a static analysis and totally ignore convection.
water vapor is the lightest of the main atmospheric gasses.
it rises to the top with no convection
Gnomish:Add heat and watervapour rises even more quickly, bypassing the absorptive layer where we measure our daily temps and cooling and emitting it at high altitude mainly to space . Also the Team never seems to consider the enthalpy aspect of this rising water vapor. It freezes and emits the latent heat out too.
i did the numbers.
water vapor carries 50,000 times more heat than co2 in any volume of atmosphere.
and that’s without any temperature change. just the enthalpy of phase change.
You know, it appears that this journalist or “science communicator” really did try to do proper job on this story. I don’t think she’s stupid, or lazy. But there’s no hiding the fact that she’s not a scientist, and doesn’t understand what she’s writing about.
Exhibit A:
Wrong. If it were true, then the Earth would never stop heating up, and we’d all be dead.
What Koll et al presumably found was that, in their model, positive water vapor feedback was just sufficient to cancel out the difference between –T⁴ Planck feedback and linear negative feedback. But that’s completely different from what this article says.
As Art and John Tillman point out above, even if it we assume that correction, it sounds like this paper is still very unrealistic. It sounds like they just ignored all the complicated feedbacks, like evaporative cooling / water cycle feedback, clouds, etc. Since evaporative cooling is the most important way that heat is transported away from the surface of the Earth, it’s obviously not something which you should just ignore!
Nevertheless, Koll’s paper might be useful at shooting down the persistent fear among climate alarmists of “runaway heating.” That fear is so obviously nonsense that I’m tempted to just write off people who talk that way, as kooks, and ignore them, like I do the chemtrailers and the Guy McPherson “near-term human extinction” nuts. But I think that would be a mistake. I was shocked, earlier today, to learn that, in an interview in 2016, Dr. Stephen Hawking revealed that even he was duped by that scare!
To the delight of the kooks at ThinkProgress Hawking said:
At first I thought that must be a fake quote. But I located the audio track, and listened to it, and he really did say that. Sadly, I fear his ALS might have been having cognitive effects, in his last few years.
“If it were true, then the Earth would never stop heating up, and we’d all be dead.”
I don’t think so. All they are saying is that water vapor feedback cancels out negative radiation (T^4) feedback. What’s left is only the original heat source. If that doesn’t increase then the heating would stop.
This tells me that water vapor feedback is extremely small.
No, Richard M, if that –T⁴ radiation feedback were completely cancelled, the heating would not ever stop.
When you “turn up the burner” and continually add increased heat to something, its temperature rises, and its temperature will continue to rise until the rate of energy loss equals the increased rate of added heat.
The only reason its temperature ever stops rising is that the rate at which it loses energy increases with temperature.
The reason it emits more energy as it gets hotter is the Planck feedback (proportional to –T⁴).
That’s as true for the planet as a whole as it is for the pan on your stove.
In fact, it is even more true for the planet as a whole than for the pan on your stove. The pan on your stove is also cooled convectively (and perhaps evaporatively, depending on what’s in the pan). But the Earth as a whole is only cooled radiatively.
If something somehow prevented all Planck feedback, i.e., if it prevented or cancelled 100% of the “proportional to –T⁴” increase in emitted radiation, then if there was an initial radiative balance, so that the temperature was raising, the temperature would never cease rising.
Dave, I don’t think they are saying anything is “preventing” Planck feedback. It is still ongoing. They are saying that the water vapor feedback just happens to be of the same magnitude as the Planck feedback with the opposite sign.
So, if you induce 1 C of warming by doubling CO2, once you subtract the Planck feedback and add the water vapor feedback you end up with 1 C of warming.
Unless something else was added to cause more warming that would it. There wouldn’t be any run away warming.
Also, from what I can tell this is a radiation only analysis. It does not consider such things as cloud feedback which is probably negative as well.
“But the Earth as a whole is only cooled radiatively.”
But not the Earth’s surface which is mostly cooled by evaporation and convection. “Greenhouse heating” is simply the increase in surface temperature needed to drive this evaporative/convective cooling at higher levels of GHG in the atmosphere. Given the other countervailing effects of more H2O in the atmosphere (higher albedo, lower lapse rate) this effect is probably very weak.
“At first I thought that must be a fake quote. But I located the audio track, and listened to it, and he really did say that.”
Well, his machine said it. Whether those were actually his thoughts, we don’t know. It sounds silly enough that it was probably his handler(s). I haven’t actually seen any video of him speaking in recent years.
Is this not, at lest partial vindication for the Sky Dragon’s and Stephen Wilde’s adbaibatic lapse rate theory?
No, it isn’t.
The sky dragon slayers think GHGs don’t heat the Earth at all. That’s just nuts.
Stephen Wilde has written, “The descending column contains the blocked 15u in the form of potential energy which heats the surface and the surface then radiates at the full range of wavelengths so as to defeat the initial blocking effect… The only effect of GHGs is to distort the lapse rate slope equally and oppositely in ascent and descent.”
That’s all wrong. The potential energy gains and losses are balanced by rising and falling air columns, but that has nothing to do with the absorption of 15µ IR by atmospheric CO2, which warms the air regardless of whether it is rising or falling, and it certainly doesn’t “defeat” the absorption of IR by GHGs in the atmosphere.
(It also has nothing to do with the the latent heat [heat of evaporation] which is transported aloft by the water cycle. When water evaporates at ground level, it absorbs latent heat, cooling the ground. When the water vapor condenses in clouds it releases latent heat, which warms the atmosphere at that altitude.)
When the rain or snow falls, there’s some potential energy converted to kinetic energy, but most of it is lost via friction to the air, still high in the atmosphere. You can tell that by the fact that raindrops and snow flakes fall, for most of their trips to the surface, at very near their terminal velocities.
Have you never noticed how the temperature drops during a cloudburst? If the falling raindrops & surrounding air were carrying lots of (kinetic) energy back to the ground, then the ground would get warmer, rather than cooler, during a cloudburst.
Dave Burton
The potential energy gain is not balanced during the formation of the atmosphere. It is only balanced once the atmosphere is in place. Thus the greenhouse effect energy develops during the formation of the atmosphere and remains for as long as the mass of the atmosphere remains in place.
If greenhouse gases then try to change the balance their effect is cancelled by changes in convection and conduction.
Any extra heating of the surface by greenhouse gases simply increases radiative emission to space so that, temporarily, energy out exceeds energy in and the surface temperatures drop back to the baseline set by the non radiative conduction/convection greenhouse effect.
The head post is correct that radiation to space rises linearly with surface temperature but it is only adequately explained by the conduction/convection model which I have proposed here:
https://tallbloke.wordpress.com/2017/06/15/stephen-wilde-how-conduction-and-convection-cause-a-greenhouse-effect-arising-from-atmospheric-mass/
Stephen, that is completely wrong.
You wrote, “the greenhouse effect energy develops during the formation of the atmosphere and remains for as long as the mass of the atmosphere remains in place…” and “…the non radiative conduction/convection greenhouse effect.”
You apparently don’t know what the so-called greenhouse effect is. It is a radiative effect, and it has nothing to do with convection.
Real greenhouses work by preventing convection, but that’s now how the (misnamed!) “greenhouse effect” from “greenhouse gases” works.
The so-called “greenhouse effect” is warming caused by absorption of longwave IR radiation, by radiatively active gases in the atmosphere, like CO2 and water vapor. The only reason so-called “greenhouse warming” happens is that the Earth is radiating LWIR radiation, and the only reason the Earth stays warm enough to radiate LWIR is that it is constantly absorbing shorter-wavelength solar radiation, which warms the surface.
Negative feedback mechanisms, like convective and evaporative cooling do, indeed, attenuate warming, but they cannot and do not “”cancel” it completely.
There are some resources here that could help you understand it:
https://sealevel.info/learnmore.html
Dave, I’m afraid it is you who have it wrong.
The Greenhouse effect is simply a term for the observation that planets with atmospheres have a surface temperature higher than planets without atmospheres. The term is neutral as to causation.
It would work even with no radiative gases as per my linked article.
That is why we see higher surface temperatures linked to atmospheric mass and NOT the proportion of radiative gases present.
The greenhouse analogy is perfectly apt for the conduction/convection cause because in descending columns of air (half the atmosphere at any given moment) clouds dissipate to let more sunlight through just like a greenhouse roof and descending air suppresses convection just like a greenhouse roof.
The radiative theorists, lacking meteorological experience, have committed a huge howler and too few were knowledgeable enough to contradict them.
I now see increasing numbers of commenters who are starting to see it and it is nothing to do with the so called Slayer position.
It is just non radiative energy transfers operating within a gas law environment.
Dave Burton
The kinetic energy in individual falling molecules is too small to be relevant to surface temperature. The issue is kinetic energy recovered from potential energy as gases become more densely packed during descent as per the gas laws.
You are correct to say it is nothing to do with water vapour.
Perhaps it coincidental, but this paper seems to unify GHG and adbaibatic lapse rate theory.
Proponents on both sides frame the argument as a binary choice. Here, they give a tacit nod to both and specify the point at which GHG’s (water vapor) will overcome high altitude heat transfer.
“Some time in the past, we think its atmosphere had a lot of water vapor, and the greenhouse effect would’ve become so strong that this window region closed off, and nothing could get out anymore, and then you get runaway heating,” Koll says.
“In which case the whole planet gets so hot that oceans start to boil off, nasty things start to happen, and you transform from an Earth-like world to what Venus is today.”
Say what? If this runaway heating already happened some time in the Earth’s past, why didn’t the Earth become like Venus back then? What am I missing?
He was talking about Venus?
The vast deep oceans of liquid water are of course the key to regulating Earth’s average temperature and preventing anything close to runaway icehouse or runaway hothouse in 4 Gy. Even the few ice house periods are probably due to to scrubbing of early CO2 before solar radiation increased due to a slowly brightening sun.
Duh.
Where’s my big grant?
Joel,
You’ve said the magic word, “CO2”, so indeed should win a handsome grant.
However, IMO, CO2 had little to do with Snowball (Slushball/Iceball) Earth episodes. IMO their initiations and terminations are satisfactorily explained by tectonic, albedo and volcanic variations.
CO2 might provide a minor feedback effect, but in all cases, solar output was weaker than today. For the last Snowball Earth interval, it was some six percent less than now (at one percent per 110 million years). The Cryogenian Period that lasted from about 720 to 635 million years ago. There was another brief glacial advance, the Gaskiers, during the following Ediacaran Period, but that might have been more akin to the glaciations of our current Phanerozoic Eon. Indeed far shorter than the Carboniferous-Permian and our present Cenozoic glacial episode.
“Crucially, the team found that the water vapor feedback is just sufficient to cancel out the rate at which the warmer atmosphere emits more heat into space.”
Doesn’t this mean the water vapor feedback is currently maxed out? If all the feedback gets emitted to space, all that is left is the base warming. We all know the warming from CO2 alone is too small to be a concern. And, soon they will discovered a couple of negative feedbacks and even that warming will be overstated.
If this is correct it supports Lewis/Curry and Monckton estimates of Climate Sensitivity over the IPCC.
Here’s my thought on this whole “tipping point”notion. When the dinosaurs had their terrible, awful,no good day, a big rock slammed into the earth at 20 or so miles per second. Estimates are that the temperature of the atmosphere rose to perhaps 600F or hotter within hours. Additionally, huge amounts of CO2 were released. Due to the rock hitting in shallow ocean waters and the heat from the blast, a huge volume of water was evaporated and thrown across the globe. There is no evidence that any tipping point was reached and the planet cooled off and life slowly got about its business.
If that wasn’t enough to tip things over then I call complete and total B.S. And while I’m at it, that goes for MIT’s 152F limit also!
Not one single mention of precipitation (aka water cycle, hydrological cycle, etc). Not one single mention of clouds. Is it even possible to produce lower-quality work than this?
Calling Chris Monckton. Isn’t linearity of water vapor feedbacks just what is needed to make his simple scheme for estimating climate sensitivity ironclad?
The IPCC focuses on sensitivity at the margin. For a given increase in temperature forcing the equilibrium temperature goes up by what mutiple of the forcing? That is the climate sensitivity at our present temperature.
But if this doesn’t change with temperature we don’t need to do a marginal anslysis. Chris says forget the fidgety hard-to-estimate high-margin-of-error-marginal changes and just look at total forcing. How much must it be getting amplified by total feedbacks to create current observed equilibrium temperatures? There is your sensitivity, total and marginal.
If feedbacks are linear that is exactly right. We don’t need general circulation models to estimate sensitivity, just some basic calculations which, as Chris has shown, yield very modest sensitivity estimates, taking alarmism off the table.
Chris has arguments for linearity in place already but these guys think they have an explanation of the why, which is a nice addition if borne out.
P.S. Lord Monckton, being the expert, could clarify, but I presume that for marginal sensitivity to equal total sensitivity (hopefully I am not bastardizing terms too much) feedbacks just have to be linear over the range of forcings that are in prospect (that it doesn’t matter if they are linear from the start any more than it matters if they are linear out beyond what is going to be seen).
If they are linear part way, then they have to be linear at the start. A chaotic system can never become linear by itself.
“[F]eedbacks just have to be linear over the range of forcings that are in prospect . . . it doesn’t matter if they are linear from the start any more than it matters if they are linear out beyond what is going to be seen. . . .”
You’re right that it doesn’t matter whether they’re linear from the start. But local linearity isn’t enough, either. For Lord Monckton’s theory to work, the ratio of the with-feedback equilibrium temperature to the without-feedback equilibrium temperature (the “large-signal” slope) has to be the same as the ratio of local changes in those quantities (the “small-signal” slope).
Unfortunately, his own numbers don’t conform to that requirement. In the last of his seven WUWT blog posts on the subject, at https://wattsupwiththat.com/2018/08/15/climatologys-startling-error-of-physics-answers-to-comments/, he says, “Here’s the end of the global warming scam in a single slide.” But in that slide the large-signal slope A is 1.13, while the small-signal slope is 1.43.
He seems nonetheless to infer linearity from the fact that for a tiny change in (without-feedback temperature) R the large-signal slope A of (with-feedback temperature) E as a function of R changes less than the rounding error.
As can be seen in the video at https://www.y https://www.youtube.com/watch?v=Ebokc6z82cg, though, what he really bases his linearity assumption on is his belief that the mathematics of feedback in all dynamical systems, including the climate, requires it.
It doesn’t.
The Venus story is terrible. Venus for the last 600 million years has had minimal erosion, meaning no water. There was something catastrophic about 600 million years ago, maybe a moon that well didn’t become a moon and the energy reformed and melted the surface to the planet. Since then there has been little erosion and anything really happening. The wind speed is maybe 5 km on the surface and the rotation is once every 243 days. The greenhouse gas likely has never let it Venus cool. The atmosphere reflects 90+ percent of the radiation. The greenhouse gas hasn’t allowed Venus to cool, it has likely stayed hot, never having an ocean.
Greenhouse effect?
what greenhouse effect?
https://tambonthongchai.com/2018/09/25/a-test-for-ecs-climate-sensitivity-in-observational-data/
https://geosci.uchicago.edu/~dkoll/publications.html
At least I found Koll’s homepage where his publications are listed. At the top of the list it gives the title of the study but of course no study because it has to appear in the climate journal before getting released.
Koll, D.D.B. and T.W.Cronin (2018), Earth’s outgoing longwave radiation linear due to H2O greenhouse effect. In press at PNAS.
If outgoing energy to space rises linearly with surface temperature then any rise in surface temperature results in outgoing exceeding incoming from the sun and the surface will cool back to the baseline temperature.
Sounds like a rebuttal of the radiative greenhouse effect leaving the non radiative conduction/convection greenhouse effect in control.
152 F. Hmm. Lessee. That’s about 67C.
Doesn’t sound so hot when you put it into real degrees.
It is actually reached occasionally by the ground temperature in the most extreme desert areas on Earth, probably never by air due to convection.
If the “science is settled”, does this mean we can safely ignore any new scientific papers?
Another model, ie, a toy.
There is no point creating models to try to understand the physical world unless all the systems are known. Without that the result is a snapshot of the level of ignorance of current understanding, and useless.
Sorry but that makes little sense.
Properly used, models can help quite a bit.
Even if there are large unknowns.
It is the flagrant misuse of models by climate hustlers that is the problem.
“he invokes Venus — a planet that many scientists believe started out as a world similar to Earth, though much closer to the sun.”
Many? Still?
Anyway, how does it explain it being linear when a considerable surface area is above 300k? How convenient that SST of open oceans rarely get over 300 K.
I get the feeling the code is written to give what the researcher wants to see.
If surface warming the last 150 years follows the co2 forcing (1,2 deg C pr doubling), all feedbacks sum up to zero. A good null hypothesis. Water vapor + clouds + lapse rate = 0.
Seinfeld had a TV show about nothing. This is an article about nothing. Earth’s temperature will not reach 152F for about a billion years. Plenty of time to party.
To this engineer the linear relationship between global temperature and outgoing radiation is obvious. Evidence for this lies in the observation that ocean temperatures rarely go much above 30C. The explanation for this lying in the physical behaviour and thermodynamic response of water to radiation flux, mainly involving Latent Heat and buoyancy.
There is a linear relationship between energy input and evaporation rate. This in turn being reflected in the vertical velocity of the Latent Heat due to buoyancy. Both of which occur at constant temperature, making the use of the Plank equation inappropriate since, in this instance, the coefficient is zero.
Water arriving as ice in the Cirrus clouds nudging the Tropopause dissipates energy to space by the mere fact that the crystals are growing. The energies involved being large and in the order of 680 plus WattHrs per kilogram of water.
The whole process being a Rankine Cycle upon the water returning to earth under gravity which varies its cycle rate in response to changes in insOlation in what I deem to be a linear relationship.
None of this can easily be explained in purely radiative terms.
I do wish these scientists would go back to basics rather than fiddling with statistical models with potential bugs in the assumptions.
“In which case the whole planet gets so hot that oceans start to boil off, nasty things start to happen..”
— As long as we’re talking about climate models where the oceans boil off, it does take a lot of heat to vaporize enough of the oceans such that you can have an ice age. Before the water can freeze on top of the continents, it has to be vaporized from the oceans. Just what is the mechanism that would vaporize the oceans as the each cools into an ice age?
I once calculated how much heat it would take to vaporize enough water to form that much ice and I accidentally melted the continents. Is there any paper anywhere, or someone with a model, or a theoretical mechanism that explains the mechanism? And why would glaciers form, instead of the moisture simply falling as snow? If it were to become gradually cooler today, wouldn’t we simply expect the ice caps to extend outward from the poles?
Snowfall that does not melt in thousands of years tends to accumulate…