Guest Post by Willis Eschenbach
Once again, the crazy idea that downwelling longwave radiation (DLR, also called infra-red or IR, or “greenhouse radiation”) can’t heat the ocean has raised its ugly head on one of my threads.
Figure 1. The question in question.
There are lots of good arguments against the AGW consensus, but this one is just silly. Here are four entirely separate and distinct lines of reasoning showing that DLR does in fact heat the oceans.
Argument 1. People claim that because the DLR is absorbed in the first mm of water, it can’t heat the mass of the ocean. But the same is true of the land. DLR is absorbed in the first mm of rock or soil. Yet the same people who claim that DLR can’t heat the ocean (because it’s absorbed in the first mm) still believe that DLR can heat the land (despite the fact that it’s absorbed in the first mm).
And this is in spite of the fact that the ocean can circulate the heat downwards through turbulence, while there is no such circulation in the land … but still people claim the ocean can’t heat from DLR but the land can. Logical contradiction, no cookies.
Argument 2. If the DLR isn’t heating the water, where is it going? It can’t be heating the air, because the atmosphere has far too little thermal mass. If DLR were heating the air we’d all be on fire.
Nor can it be going to evaporation as many claim, because the numbers are way too large. Evaporation is known to be on the order of 70 w/m2, while average downwelling longwave radiation is more than four times that amount … and some of the evaporation is surely coming from the heating from the visible light.
So if the DLR is not heating the ocean, and we know that a maximum of less than a quarter of the energy of the DLR might be going into evaporation, and the DLR is not heating the air … then where is it going?
Rumor has it that energy can’t be created or destroyed, so where is the energy from the DLR going after it is absorbed by the ocean, and what is it heating?
Argument 3. The claim is often made that warming the top millimetre can’t affect the heat of the bulk ocean. But in addition to the wind-driven turbulence of the topmost layer mixing the DLR energy downwards into lower layers, heating the surface affects the entire upper bulk temperature of the ocean every night when the ocean is overturning. At night the top layer of the ocean naturally overturns, driven by the temperature differences between surface and deeper waters (see the diagrams here). DLR heating of the top mm of the ocean reduces those differences and thus delays the onset of that oceanic overturning by slowing the night-time cooling of the topmost layer, and it also slows the speed of the overturning once it is established. This reduces the heat flow from the body of the upper ocean, and leaves the entire mass warmer than it would have been had the DLR not slowed the overturning.
Argument 4. Without the heating from the DLR, there’s not enough heating to explain the current liquid state of the ocean. The DLR is about two-thirds of the total downwelling radiation (solar plus DLR). Given the known heat losses of the ocean, it would be an ice-cube if it weren’t being warmed by the DLR. We know the radiative losses of the ocean, which depend only on its temperature, and are about 390 w/m2. In addition there are losses of sensible heat (~ 30 w/m2) and evaporative losses (~ 70 w/m2). That’s a total loss of 390 + 30 + 70 = 490 w/m2.
But the average solar input to the surface is only about 170 watts/square metre.
So if the DLR isn’t heating the ocean, with heat gains of only the solar 170 w/m2 and losses of 390 w/m2 … then why isn’t the ocean an ice-cube?
Note that each of these arguments against the idea that DLR can’t warm the ocean stands on its own. None of them depends on any of the others to be valid. So if you still think DLR can’t warm the ocean, you have to refute not one, but all four of those arguments.
Look, folks, there’s lot’s of good, valid scientific objections against the AGW claims, but the idea that DLR can’t heat the ocean is nonsense. Go buy an infrared lamp, put it over a pan of water, and see what happens. It only hurts the general skeptical arguments when people believe and espouse impossible things …
w.
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Get thee back to school Willis 😛
DLR heats the top 10um and the top millimeter has a negative temperature gradient. The very top of the ocean is colder than it is about 1mm down. Think that through and then rephrase your arguments.
Its true the DLR “heats” the ocean but not in the manner you or most others believe. The “heating” is almost entirely related to a reduced rate of cooling. That makes a big difference to how ocean heating should be viewed.
DLR doesn’t exist. It’s the artifact of a mathematical mistake by Sir Arthur Milne in 1922 when he used an infinite atmosphere boundary condition to solve the PDE for IR absorption.
‘Climate science’ made another mistake when it believed the radiometer pointed upwards measured DLR. That signal is real, but exactly counterbalanced at equilibrium by IR in the opposite direction.
Grizzled engineers like me know this because it’s the first law of Radiation – Prevost’s theory of Exchanges [1840].
So the question you pose is irrelevant.
There are a lot of strange and wonderful thing happening in the first mm of water! GK
Here’s an experiment. Let me know how it turns out.
At normal room temperature fill two identical styrofoam cups with water at 98.6F. Hold your hand about a foot over the top of one of them. Your hand will be providing extra downwelling radiation to that cup. After a few hours measure the temperature in both cups. Let me know how much warmer the cup is that had the extra downwelling longwave radiation. Thanks in advance for actually performing an experiment instead of bloviating about physics you don’t understand, Willis.
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Thanks Willis
I have made the point several times before that people who deny the basic physics undermine the efforts of scientists who challenge the AGW theory. If the theory of DLR and its dependence on CO2 was really as flakey as some would suggest the sceptics would have won the argument 20 years ago. The issue is only about the magnitude of the effect not its existence. The trouble is that climate scientists can point to these silly pseudo scientific arguments as justification for ignoring all the sceptics arguments.
“Your suggestion of putting an infra red source over a pan of water was I believe the most sensible part of your post.”
Yes, it is. The infrared source should be approximately the same temperature as the water because that’s how it is over the ocean where the air temperature is very near the sea surface temperature. I know what the result will be. Willis is in for a big surprise.
The warming of the surface layer of a lake/ocean isn’t evidence that LWR is absorbed. Solar radiation is clearly the primary source of this heating.
In calm tropical oceans, an hour of cloud versus an hour of sunlight has a noticeable effect on how warm the surface layer of water is.
Otherwise, the important question is,
Does the increase in Downwelling LWR (from increased GHGs) cause ocean warming and if so, by how much?
The answer is almost certainly yes it does, but by (much?) less than the climate models predict (and require for their claim of accurately modeling the climate to stand up).
“”””” Look, folks, there’s lot’s of good, valid scientific objections against the AGW claims, but the idea that DLR can’t heat the ocean is nonsense. Go buy an infrared lamp, put it over a pan of water, and see what happens. It only hurts the general skeptical arguments when people believe and espouse impossible things … “””””
Well first off, an “infrared lamp” has a temperature in the range of about 1000 K and is not too bad an imitator of a black body radiator, being incandescent. That said it emits near infra red radiation that peaks at about 1.0 microns wavelength and also at about 4.0 megaWatts per square metre. Compare that to the average atmosphere which has a Temperature around 288 K, and is emitting wavelengths more in the 10 micron range and about 400 W/m^2.
So your heat lamp is 10,000 times the radiance of the atmosphere, and is spectrally peaked where H2O is an extremely good absorber, in fact at 3.0 microns, H2O has its maximum absorption coefficient of around 10^4 cm^-1..
Why not use an ordinary bottle of water at about 15 deg C (288K) as a source to demonstrate how “downwelling” LWIR radiation heats the ocean.
And that 10-15 micron radiation from the atmosphere is absorbed in more like the top 50 microns (99%) of the surface, not the top mm.
On the other hand, the solar energy can go 100s of metres deep in the oceans before full absorption.
So we are being asked to accept that a thermal energy source at a mean Temperature of about 288K (some say it is only 255K) can thermally excite GHG molecules (CO2), causing them to emit LWIR radiation at a wavelength around 15 microns, and that radiation (well maybe half of it) gets absorbed in the ocean which has a much higher specific heat, and will be absorbed in no more than 50 microns of sea water, most of which is already at a much higher temperature than the 255 or even 288 atmospheric source.
Temperature. The Temperature gradient would seem to be in the wrong direction at the surface, to cause much conduction of that surface “heating” into the depths.. I’ve spent enough time out in the deep oceans to believe that most of the time, the deep oceans are rather calm, and deep mixing due to turbulence is far from the norm.
But as to whether “downwelling” LWIR from GHGs can heat the ocean; I don’t know; I’d like to see the results of some actual measurements that demonstrate the phenomenon.
http://www.warwickhughes.com/blog/?p=87
Per Doug Hoyt:
“You are right. To be accurate, DLR means that the surface is warmer than if the DLR weren’t there. So you are technically correct, but in common parlance we don’t usually say “It slows the cooling so it ends up warmer than it would otherwise”. We just say “it warms it”.”
you know willis I think is one of the major miscommunication problems in radiative physics.
One way to think about it is this.
The shiny surface on a thermos does not warm the coffee inside.
The shiny surface retards the heat loss via radiation.
I sit outside on a freezing winter night with a space blanket.
The blanket doesnt warm me. The blanket slows the heat loss via radiation.
Now go have fun with tallblokes toilet paper experiment
I could not have said it any better myself Willis.
But it won’t go away because the desire to believe is stronger than any rational argument. There are even university professors who should know better pushing this particular piece of nonsense.
And if commenters disagree go do the experiment as Willis says.
Of course if that extra downward DLR DOES get into the oceans then we have thousands of years before the ocean temperature would change enough for us to notice any climate effect. The same energy cannot be in two places at once and the heat capacity of the oceans is magnitudes greater than that of air.
Willis, what proportion of DLR do you contend gets into the oceans ?
No, the truth is that it does not warm the oceans but it DOES add to the energy content of the system from those affected molecules upwards through the atmosphere to space.
Thus there IS a climate effect but it is manifested by a change in the surface pressure distribution from more radiation convection conduction and evaporation.
The problem for AGW then is that such changes are miniscule compared to the natural forcings of solar and internal oceanic variability.
Full analysis here:
http://www.irishweatheronline.com/news/environment/wilde-weather/setting-and-maintaining-of-earth%e2%80%99s-equilibrium-temperature/18931.html
This issue is not comparable to denial of the existence of a greenhouse effect. I am here accepting the warming capability of GHGs but simply advancing the description as to how they influence the system and in doing that it is not possible to have such a tiny effect warming up both vast oceans and the atmosphere to a significant degree simultaneously (or even separately) because all they do is accelerate the energy flow through the system to offset that warming effect.
Radiative processes alone need to warm up an entire system to a higher equilibrium temperature in order to regain balance. That is true and the essence of AGW.
In this case radiative processes are not acting alone. Other processes are speeding up the energy flow out to space which reduces the need (or possibly eliminates the need) for any rise in equilibrium temperature for the system as a whole.
It should be very easy to test this per Doug Hoyt’s example.
Sorry, I’m not buying that 100 ppm increase in CO2 can have any measurable effect on ocean temperature.
Water has a shiny surface……
Swift says:
August 15, 2011 at 3:17 pm
“The Science of Doom has the first of a very good multi post series on DLR and the ocean here http://scienceofdoom.com/2010/10/06/does-back-radiation-heat-the-ocean-part-one/
Most of the questions that have been asked and will be asked are answered there.”
The science of doom article has a huge glaring flaw in part two. It uses a simple application of the Stephen-Boltzman law on perfect black bodies to show the temperature of the ocean with and without DLR and concludes DLR must heat the ocean because otherwise it would be -15C instead of plus 15C.
The flaws are twofold. First of all, unlike the surface of a black body, the ocean is a greenhouse unto itself. Shortwave radiation easily penetrates to a depth of some 100 meters depending on clarity. This is absorbed and warms the water. Water is just about totally opaque to long wave radiation so none of that solar heated water below the surface can cool radiatively until it is somehow mechanically transported to the surface. These are the exact same properties that CO2 has – transparency to visible light, opacity to infrared. You can’t have your cake and eat it too. If CO2 is a greenhouse gas then the ocean is a greenhouse fluid.
The greenhouse properties of liquid water is what raises its temperature far above what it would be if it were a passive black body surface.
The second flaw in the science of doom black body graph is that black bodies don’t give up heat by evaporation. The ocean does. In fact that’s the primary cooling mechanism. 70% of the solar heat in the ocean escapes by evaporation, 20% via radiation, and 10% via conduction. Moreover the ocean retains a lot solar heat absorbed in the summer and releases it in the winter when the air is dryer and evaporation rate is faster. That’s why there’s a much smaller seasonal temperature change in the ocean versus land. The much greater seasonal temperature variation over land is called continentality.
Willis might have learned a lot about the ocean by sailing, surfing, and diving but he evidently needs to learn more about land by doing some driving and digging. The notion that land and water are equivalent in the way they heat and cool is demonstrates utter ignorance of both.
Firstly, who uses “DLR”? Do you mean downwelling thermal infrared? And what do you mean argument against warmistas that it can’t?? The warmistas claim it can’t!
What an odd distortion. The AGWScience argument is that it is “Solar” energy of Visible Light and the two shortwaves either side of UV and Near Infrared which heat land and oceans. They say that longwave infrared, thermal infrared, doesn’t play any part in heating the land and oceans. That’s the picture they give of the Earth as a ‘greenhouse’, that shortwave visible gets through the ‘glass’ of the atmosphere and heats the ground, land and oceans, and thermal long wave infrared doesn’t get through ‘the glass atmosphere’, but then radiates out from the ground and gets trapped by the ‘glass/atmosphere’.
This is ‘standard’ teaching on it, the AGWScience fiction meme gone viral in the general education system – ‘everyone’ takes it so much for granted because it has been so successfully brainwashed.
“When the outer atmosphere or the ozone layer does not trap short wave radiation from the sun, it penetrates the surface of the Earth. This energy is then re-radiated back as energy of a longer wavelength (infrared). This leads to a warming of the Earth’s surface and the lower atmosphere.” http://education.gsfc.nasa.gov/ess/Units/Unit2/U2L5A.html
Light waves, the short electromagnetic of Visible, and the two shortwaves either side are not capable of heating land or oceans. The AGWScience meme is junk science. It claims that blue visible light heats water!!
How???
It’s an argument I’ve been having for quite a while with folks here, those ‘educated’ into believing it, I’m so glad you brought it up.
Just to get this straight. The AGWScience fiction claim is that shortwave converts to heat land and oceans and longwave thermal is radiated out – downwelling SHORTWAVE, Light, upwelling LONGWAVE, heat. By “Solar” they mean these shortwaves and not longwave thermal infrared. See the Kiel/Trenberth 1997 for the AGWScience fiction Basic Energy Balance on which all the has been built. They’ve been denying that longwave thermal infrared heats the Earth!
It’s been the same claim for rather a long time, so long in fact, that even ‘skeptics’ think it is real physics. It’s gobbledegook. Here’s an example: http://wattsupwiththat.com/2011/05/07/visualizing-the-greenhouse-effect-light-and-heat
“Solar “light” radiation in = Earth “heat” radiation to Space out! That’s old news to those of us who understand all energy is fungible (may be converted to different forms of energy)”
Forget about the watts in/watts out and all the aguments about ‘backradiation’ – it’s the basic physics that is unadulterated d cr*p here…
This perverse physics which has given thermal ability to light, shortwave, and denied that longwave thermal infrared heats the Earth has been systematically taken out of references whenever it can be. AGWScience fiction plays around with properties and processes. The example I found earlier of a NASA page for children which taught the real physics that thermal infrared is the heat we feel from the Sun has been dropped – and this nonsense that thermal infrared doesn’t even reach the Earth’s surface has been put in its place – here’s the post:
http://wattsupwiththat.com/2011/07/28/spencer-and-braswell-on-slashdot/#comment-711886
Thanks for trying with the secure connection Anthony, but you go away for the day and it’s back to the same old interference.. It was good while it lasted.
Willis, Gary Wilson, crosspatch, Climate Weenie etc …
I am not sure what the main thrust of this post is (or is ssupposed to be).
The existence of IR radiation downwards is not disputed AFAIK. But as already pointed out, the IR-exchange between to bodies depends on mainly their respective temperatures, and for gases also the spectral properties of the radiating molecules.
And since noone disputes that the net heat flux from the earth’s and ocean surfaces is outgoing, everybody is aware of that in- and outgoing IR-radiation mustbe there at the same time. They are counterparts of each other. The net heating of the surface is by sunlight short wave radiation, making it all the way to the surface. (There is also a part of the sun’s IR being absorbed in the atmosphere and there reradiated in all directions, so that part of the ‘downwelling’ IR also originates from the sun, and only the remainder can be attributed to the ‘greenhouse effect’, but thats a minor detail).
The ‘greenhouse effect’ slowers the IR-radiating cooling mechanism (which would be zero if one had a perfect 100% IR-mirror holding it just above the surface). The net received heat must however be cooled away (in steady state) and the other available cooling mechanisms are mechanical transfer of heat through: Thermal convection and transport of phase-transitioned water vapor, both being heat transported uppwards from the surface.
I don’t think you’ve got this wrong, but I object to the notion that there are ~170 W/m2 (SW-sun)) plus ~330 W/m2 (atmospheric DLR), adding upp to a ~500 W/m2 total. Because the the DLR part is an ongoing inner process, which is only ~half of an ongoing exchange, which by necessity has and must have flows in both directions. between two adjacent bodies each with a temperature. The outgoing counterpart being somewhat larger, ~390 W/m2.
There are only a total of ~342 W/m2 of heating available, and all of that is from the sunlight. Inner processes are going on inside the atmosphere, that’s true. But saying that ~500 W/m2 heats the earth’s surfaces is awkward.
Here in Christchurch N.Z i take ground temperatures at one metre deep.
The ground temp ranges between 8.9c(record, recorded in the last 3 weeks) to a high of 16.8c in summer. What iv noticed when we get a warm sunny day (say 26c) and even if the next 2 days are only 18-20c( cloudy or sunny ) i get a 0.2c increase in the ground temp 3 days after the warm day.The same happens when we get a cold day too 3 days latter a drop in the ground temp of 0.2c.
If we have a prolonged cloudy period say 2weeks temps at one metre underground only change about 0.3c over that period(usually down).If the skys are clearer over the same period the temp can go up or down by up to 1c.
My conclusion is then that DLR even gos deeper into the ground than what most think.
In a discussion elsewhere on this topic, I made a mechanical analogy (for the case of perfect IR-radiation insulation, ie 100% greenhouse effect):
The analogy is undefirmed mechanical equlibrium, corresponds to thermal equlibrium (all temperatures being equal), and that deformed state, due to external load (or heat source) correspond to thermal steady state, with net deformation and/or net heat flow, determined uniquely by the the external load, and where it is applied.
Yet another general misconception is that all the water molecules in any arbitrarily thin layer are at the same temperature. That isn’t how it works. Some of those molecules are boiling hot and some are ice cold. The average of many of them is the temperature. Evaporation occurs because at any one time some water molecules get bumped, literally, over the edge of latent heat of vaporization. If they are surrounded by other water molecules they don’t get to stay vaporized because they are surrounded by cooler molecules which they bump into and give up the heat. However, if they are on the surface, they have a free path to leave as a molecule of water vapor.
Downwelling IR, because it can’t penetrate more than a few microns, is continually bumping surface molecules over the edge of latent heat of fusion and they fly away. For those molecules that don’t get enough of a bump they don’t mix downwards because wave and winds causing mixing well below the surface not actually on the surface and second because warmer water rises above cooler water. At the end of the day downwelling IR does not cause any significant heating (or, for pedants, lowered rate of cooling). All it does is raise the evaporation rate and the energy is carried aloft as latent heat of vaporization and doesn’t get released to the environment as sensible heat until it condenses. The release generally happens at the cloud deck when adiabatic cooling reduces the water vapor temperature below the dewpoint. Downwelling IR warms the cloud deck and has no direct effect on surface temperature. All it does is lowers the temperature gradient of the atmosphere between surface and clouds and raises the temperature gradient between clouds and outer space.
For what it’s worth, here is a paper that may add to this discussion ‘Induced Emission and Heat Stored by Air, Water and Dry Clay Soil.’ Nasif Nahle http://www.biocab.org/Induced_Emission.html
“Abstract: In this paper, I have resorted to basic formulas obtained from experimentation and observation by several scientists for calculating the heat stored by any substance and the subsequent change of temperature caused on a determined system. I demonstrate that the climate of Earth is driven by the oceans, the ground surface and the subsurface materials of the ground. I explain also how the photon streams from oceans, ground and subsurface materials of ground overwhelm the emission of photons from the atmosphere to the ground during both daytime and nighttime…. Concluding, atmospheric gases do not cause any warming of the surface given that induced emission prevails over spontaneous emission. During daytime, solar irradiance induces air molecules to emit photons towards the surface; however, the load of Short Wave Radiation (SWR) absorbed by molecules in the atmosphere is exceptionally low, while the load of Long Wave Radiation (LWR) emitted from the surface and absorbed by the atmosphere is high and so leads to an upwelling induced emission of photons which follows the outgoing trajectory of the photon stream, from lower atmospheric layers to higher atmospheric layers, and finally towards outer space. The warming effect (misnamed “the greenhouse effect”) of Earth is due to the oceans, the ground surface and subsurface materials. Atmospheric gases act only as conveyors of heat.”
In peril of sounding like a Warmista, which I’m not, what else could possibly heat the oceans but long wave IR? Reminds me of if not CO2 then what else could it be…. Nothing that I can think of. Well, maybe not the oceans but the near shore waters have another possible explanation.
Back in the 80’s I had a boat and often went to Egmont Key, an island on the mouth of Tampa Bay – beautiful pristine clear waters. One time, and against my better judgement, we went out on Labor Day. Along a 1-mile beachfront I found only one spot where I could back up an 8-foot beam boat onto the beach. While there I did some back of the napkin calculations on the amount of beer consumed by the hundreds of people there, and the resulting urine going into the water at 98-degrees or so. Story short, the waters close to the beach were a lot warmer :). And I stayed out of it!
Best,
J.
re: Alexander Duranko says: August 15, 2011 at 3:28 pm
Anyone ???, I’m hearing crickets on this item.
What is the primary source of DLR over the tropical oceans?
Any chance It would happen to be water vapor?
steven mosher says:
August 15, 2011 at 4:07 pm
The reflective surface is not the primary mode of insulation. “Thermos” is a brand name that became attached to all of what were orginally known as “vacuum flasks”. The primary means of insulation is the vacuum between the inner vessel and outer walls which stops almost all conductive heat transfer. Most the remaining heat loss is blocked by the reflective coating. That’s why laying tin foil over non-reflective attic insulation doesn’t help a whole lot but does help some.
Addition to the 1:st of my posts just above: The net heat flux (in thermal steady state) in and out from any surface is of cause zero:
I was referring to the net of the IR-radiation. The non-short-wave-radiations from the sun, hitting the earth’s surface of course equals the net heat loss from the very same surface. Due to the three different cooling mechanisms: IR exchange with adjacent bodies, qater evaporation and thermal convections (conduction too, but negligable here)