The Greenhouse Effect in a Water World

The natural world is complicated. Therefore, so is the science that tries to understand it.

Complexity, uncertainty, ambiguity are all a part of the story that describes processes that are as extraordinary as they are mundane. While these are the very characteristics of scientific study that motivate professional and amateur alike, they are also the characteristics that give delayers, doubters and liars in the climate debates ample material for confusing and misrepresenting reality.

One such complexity is the interaction of infra-red or long wave radiation (IR or LW), the ocean surface and the atmosphere. This is what gives rise to one of the more esoteric arguments in the climate change denier's arsenal, the argument that the Greenhouse Effect does not operate over 70% of the earth's surface, the portion that is covered in ocean rather than land and therefore ocean warming can not be a result of an enhanced GHE from rising CO2. Since ocean heat content is by far the lion's share of climate system warming...um..Not the IPCC.

The grain of truth in this line of reasoning is that ocean warming is primarily from solar short wave (SW) radiation, the visible light, that freely propogates through the atmosphere and penetrates 10's of metres into the ocean's upper layers. This sunlight directly warms the ocean waters just as it directly warms the earth's surface. Recall now that the greenhouse effect is what happens next: all warm bodies, land and water, emit longwave radiation and these IR photons are trapped and re-radiated by greenhouse gases (H20, CO2, CH4 among others). Roughly half of the energy the surface of the earth tries to send back out to space returns this way. So, the GHE increases down-welling LW but not SW energy. Well, it just so happens that this returning LW energy, unlike its SW cousin, does not penetrate water beyond a few micrometres and therfore it can not directly warm anything but an insignificant portion of the upper ocean layers. No increase in SW radiation, no ocean warming.

To be honest, I am not sure what is so compelling about this argument. Firstly, the climate we inhabit exists in the bottom of the troposphere over land, so while not insignificant, warming of the ocean is not our primary concern. Secondly, energy is not destroyed, so absorbed directly or not, the fact is it is having its escape from the earth's surface, be it land or water, impeded and this must show up as warming somewhere. Logically, some of it must be finding its way back into ocean water via some means or another. Skin layer water molecules that evaporate rather than allow the IR energy to pass through will immediately or eventually give that heat up again as they condense back to liquid form. This results in warmer air which can transfer its heat via conduction. Admittedly, this is probably a minor factor as the heat capacity of air is so much less than water, but that heat does not just disappear. And finally, whatever is going on, the fact is that the heat content of the upper ocean is rising, as expected in an enhanced greenhouse environment. A truly inquiring mind would search for the mechanism that explains the reality, not declare that reality is impossible so... "drill baby, drill!"

Well, it turns out that reality is possible and is happening for a reason, no matter how complicated or surprising. The reason is that that very thin skin layer of water on top of the ocean surface is a strong controller of the heat flux between atmosphere and ocean. Specifically, the size of the temperature gradient between the surface layer and the bulk temperature of the mixed water below it determines how well heat can propogate through it. Now, there are two possible directions heat might propogate. In polar regions or winter in temperate climates, the air is much colder than the water and so heat will flow out of the ocean, whereas in the tropics or summer temperate climates the air will be warming the ocean, drawing energy out. If increased down welling LW is causing a warming of the skin layer, then in the first situation, where the ocean is warmer than the air, the gradient is increasedreduced and in the second, where the ocean is colder, the gradient is reducedincreased. The larger the temperature gradient, the faster heat will move across it.

This image and caption, taken from a RealClimate article on this subject, shows the relationship we are looking for:
i-1f23daa61f7ba070b84873a6b5cbf494-Minnett_2-thumb-500x476-66551.gif
Figure 2: The change in the skin temperature to bulk temperature difference as a function of the net longwave radiation.

Please check out that RC article and the first couple of screens of comments for the rather gory details.

Because of the principal of larger temperature gradients causing faster heat transfer, by warming the skin layer, down welling IR will decrease the heat transfer from warm ocean to cold air and increase the heat transfer from warm air to cool water, both of which effects contribute to warmer upper ocean waters. Ocean waters warmed by the direct sunlight find that, in an enhanced greenhouse environment, more of this heat is retained rather than passed into the atmosphere.

It is a bit of a brain twister, I'll admit, but it is all consistent with well known physical properties of energy transfer and well established observational evidence of warming upper oceans.

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Thanks Coby. I read the final posts on the previous thread and finally understand what Vernon was driving at.

If someone truly wants to understand this issue, then this link provides some reasonable reading:

http://eospso.gsfc.nasa.gov/science_plan/Ch3.pdf

Simply speaking, ghg do not warm the oceans - they prevent it from cooling. But then, that is such a simple concept that I am surprised that some people don't get it.

Awesome. It took me some time and several reads (the article and comments on RealClimate helped a lot) but I think I understand it now. Basically the LW radiation heats the top layer of the ocean which reduces the temperature difference between that layer and the rest of the ocean. That, in turn, "insulates" the ocean from the atmosphere and heats up. Would it be fair to characterize it as an "oceanic greenhouse effect"?

I love this complex mechanisms. It is humbling to realize that nature is always has some other Ace under her sleeve (or under her skirt, that slutty mother nature).

Coby,

Theis a repeat of a blog entry at RC which has never appear in the peer reviewed literature that I was able to find. If you can find where it was published than I would like the link to that if possible. I find it hard to believe that on this site a singe reported test that was presented in a blog that has never been peer reviewed is presented as the answer to a pretty significant issue with the GHG theory. All the peer reviewed papers I could find all agree that LW down dwelling radiation causes cooling on the ocean. The only place I have found that makes the claim that it warms the the water is from the RC site and now you.

Basically, do you have any peer reviewed literature that supports this claim or is it just an unsupported claim from RC being repeated?

"to a pretty significant issue with the GHG theory"

Except... it _isn't_ (and shouldn't be) a significant issue with standard physical theory except with a few crazy people. If you turn up the air temperature in your house, does the bathtub warm up?

"All the peer reviewed papers I could find all agree that LW down dwelling radiation causes cooling on the ocean. "

Please point us to some.

Vernon does not disappoint, he says exactly what I predicted he would say in the previous thread:

Anything anyone says to answer your questions gets the same response. "It is all wrong because it does not say what I want it to say".

By Ian Forrester (not verified) on 24 Jun 2011 #permalink

If you turn up the air temperature in your house, does the bathtub warm up?--M

The point seemed so simple and obvious that I was afraid to ask it. Did I miss some key subtleties earlier?

The simple answer to this one is that the oceans are not 33K colder than the atmosphere, for reasons which should be patently obvious.

However, your explanation is a little off:

The reason is that that very thin skin layer of water on top of the ocean surface is a strong controller of the heat flux between atmosphere and ocean. Specifically, the size of the temperature gradient between the surface layer and the bulk temperature of the mixed water below it determines how well heat can propogate through it. Now, there are two possible directions heat might propogate. In polar regions or winter in temperate climates, the air is much colder than the water and so heat will flow out of the ocean, whereas in the tropics or summer temperate climates the air will be warming the ocean, drawing energy out. If increased down welling LW is causing a warming of the skin layer, then in the first situation, where the ocean is warmer than the air, the gradient is increased and in the second, where the ocean is colder, the gradient is reduced. The larger the temperature gradient, the faster heat will move across it.

If the temperature gradient is increased in the case where heat is leaving the oceans, and decreased in the case where it is entering, that should lead to an overall cooling effect, not a warming. But the gradient which matters here is that between the skin and the ocean bulk, not that between the skin and the atmosphere.

[Thanks, Martin, I inadvertently swapped "reduce" and "increase" in the passage you quote here, I have ammended the article... - coby]

Coby,

All the peer reviewed papers I can find agree that the net down dwelling longwave radiation on the ocean surface leads to an global average of -66 wm2 which is cooling. (I have no desire to publish a list of papers for those to lazy to do their own research.) Yes Ian is right, presenting me an regurgitation of an unpublished, non-peer reviewed, blog post is going to get the same reaction I gave it the first time.

Please explain how GHG theory, which says that down dwelling LWR causes the surface to be warmer than it would be with out the GHGs in the atmosphere works over the 71 percent of the earth that is not solid? Where increased down dwelling LWR cools the surface of the ocean, where the only warming comes from SWR which will, unlike LWR, penetrate the surface.

Basically, how does cooling the ocean surface cause ocean to retain more heat.

Since 3/4 of the Earth's surface is water the idea that it is not of importance to the alleged catastrophic warming of the globe seems bizarre.

These 7 questions seem to go to the heart of the warming scare since if any of them cannot be aswered in a way that supports alarmism then there is no case to answer. For some reason Mr Mann has declined to answer them privately (as indeed has every other warming alarmist asked:

1 - Do you accept Professor Jones' acknowledgement that there has been no statistically significant warming since 1995?

2 - Do you accept that the rise in CO2 has improved crop growth by around 10% & that the consequent influence on world hunger is more beneficial than any currently detectable destructive action of alleged global warming?

3 - Do you accept that the Hockey Stick, as originally presented by Mann and the IPCC contained calculations that were inconsistent with good science and that Mann's refusal to make calculations and algorithms available for checking were inconsistent with scientific principle?

4 - Do you accept that many claims from people and organisations on the alarmist side, from Al Gore's claim that South Sea islands had already been abandoned due to rising sea levels and Pachauri's claim that any dispute that the Himalayan glaciers will have melted by 2025 was "voodoo" were untrue and insupportable even at the time.

5 - Do you accept that there are a number of geoengineering solutions which arithmetically can be shown would work (including stratospheric dust, the geritol solution or even just replacing CO2 burning with nuclear power) which would work at a small fraction of the cost of the war against fire, or in the case of nuclear, at negative cost?

6 - Do you accept that the refusal of alarmists to denounce fraud or telling of obvious untruths. on their side, or even its active support or covering up, detracts from the credibility of the entire movement?

7 - Of the alleged "consensus" - can you name 2 scientists, out of the roughly 60%, worldwide who are not paid by the state, who support catastrophic warming & if not can you explain how something can be a consensus when no member of a subset of 60% of the alleged consenting, consent?

By Neil Craig (not verified) on 24 Jun 2011 #permalink

All the peer reviewed papers I can find agree that the net down dwelling longwave radiation on the ocean surface leads to an global average of -66 wm2 which is cooling.

Average of *what*, Vernon? Just the surface of the ocean? Just the ocean? The entire climate system? Clarify, because as per Coby's conservation-of-energy argument in the lead post this is counter-intuitive as written and requires clarification.

(I have no desire to publish a list of papers for those to lazy to do their own research.)

That's just brilliant, Richard Wakefield: "My proof is out there; if you don't dig it up that's your problem."

I might try your line in my next article submission in lieu of a lit review. Incredible.

Skip,

Let me think... the ocean, what do you think this discussion is about? They teach this in schools, for example on page 5 of this presentation used at Yale:

http://earth.geology.yale.edu/~avf5/teaching/ResourcesGG535/Lecture9.He…

Since you may not understand the chart, down dwelling LW is "net infrared radiation", which is negative. The only source of warming is the SW from the sun. LW radiation cannot penetrate water more than a few microns at most. All LW radiation does is promote evaporation which is cooling, not warming.

Ok Vernon I will read your link but this better be good.

All the peer reviewed papers I can find agree that the net down dwelling longwave radiation on the ocean surface leads to an global average of -66 wm2 which is cooling.

So what? It's the change in down-welling LR due to increased GHG concentrations that's relevant. Whether that's a change from positive to more positive, or negative to less negative, is entirely irrelevant.

For some reason Mr Mann has declined to answer them privately (as indeed has every other warming alarmist asked:

Liar. They've been answered repeatedly on multiple scienceblogs. In fact, everywhere I've seen you post them, they've been answered. You just don't like the answers, so you pretend they were never given.

Vernon, looking at the global heat balance diagram on pg 3 of your link in @12 I see the same number (net 66 W/m^2 heat lost) for downwelling LW radiation. This would be the value for QLW in the equation on page 5:
Q = QSW â QLW â QS â QL

Fine, we can take that as agreed. It does not mean what you are implying and also it obviously must be a negative number as Q in an equilibrium state must be 0, QS and QL are small numbers and QSW is large.

The oceans warm primarily via incoming SW and do not emit SW therefore not outgoing LW must be positive (net incoming must be negative) for a balanced equation.

You need to suggest some plausible mechanism whereby holding QSW steady and increasing downwelling LW does not make Q greater than 0, which represents a warming imbalance.

I would also like to point out that:
"down dwelling LW is "net infrared radiation", which is negative. The only source of warming is the SW from the sun." is not in and of itself correct. Just because *net* is negative does not mean it has no positive component, which it does.

I did not know that, Coby, although it makes perfect sense.

The other thing I noticed was that the graph was sourced from an IPCC resource by Houghton and I believe Kevin Trenberth. And yes this does appear to be the source of Vernon's -66wm2 figure, although the graph refers to the whole energy budget of the atmosphere not just the ocean. This is less than a prohibitively cumbersome list of "peer reviewed literature" but wave that point and accept it face value.

Because while I don't claim to understand the scientific nuances of this issue yet, the sources themselves are inimical to any notion of incoming solar radiation having a net cooling effect.

In fact if I'm not mistaken the graph is taken straight from the SAR (1996)--and Trenberth not specifically involved-- and the percentages added for purposes of the slide show you linked, Vernon.

When the bottom of this has been gotten to I seriously doubt we're going to find any vindication of a cooling effect of sunlight striking the ocean.

First, I never suggested there was a cooling effect from sunlight, which is SW, striking the ocean. I am pretty sure that I said the opposite of that, that SW is from the sun is the source of warming. Second, if the ocean was a solid, then I would agree Coby, but it is not. It is a liquid that has some pretty special properties. Namely that it will absorb all the LW in the bandwidths of GHG produced down dwelling LW, which means not only is the first few microns the only place that down dwelling LW can be absorbed but it is also the only place that radiates LW. That being said, water pretty much does not cool by long wave radiation but by evaporation. This causes the surface to cool and since the surface is cooler, it sinks and warmer water moves to the surface to be cooled or evaporated.

That is why what you posted and RC posted would be a clear break from all previous studies that I have read, however, other than at RC as a blog post, I have not found that presented in the peer reviewed literature. Since it has not be peer reviewed, I am sticking with the peer reviewed science.

All that is said to make this point. I have found no study that shows that down dwelling LW does slows the cooling of the ocean. Please point me towards that.

The greenhouse effect over oceans was measured as early as 1999 using the ERBE programme.

Raval and Ramanathan (1989) used ERBE
clear-sky LW fluxes over oceans to validate
climate model calculations of the greenhouse
effect. They demonstrated that the water vapor
content of the atmosphere is thermodynamically
constrained by the surface temperature. Figure
5, adapted from their results, shows the
greenhouse effect or warming of the Earthatmosphere
system by atmospheric gases as
related to sea surface temperature. The ERBE
data verify the magnitude and variation of the
greenhouse effect with sea surface temperature.
The upturn of the curves at high temperatures
indicates that the model's estimate of a rapid
increase in atmospheric warming at high sea
surface temperatures is confirmed by the ERBE
results. While the validity of their investigation
has been strongly debated, the analysis does
illustrate the value of ERBE data in climate
process studies.

More recent measurements have been made by the CERES satellite program.

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19990064139_199910…

By Ian Forrester (not verified) on 25 Jun 2011 #permalink

Ian,

I read that and and then tried to access the actual study, but I could not. The Raval and Ramanathan (1989) abstract "The greenhouse effect is found to increase significantly with sea surface temperature." I will freely concede that as SST increase the GHG will increase, that is the expected outcome when SST cools mainly via evaporation. But want I did not find was any statement that an increase in GHG caused SST to increase. Where is the change in GHG to change in SST relationship, I did not find it in this document.

Because WV changes with SST would appear to be an self evident. What is not evident is how an increase in GHG will cause SST warming and what the mechanism is. Do you have any studies that address this? I cannot find any.

[comment moved to the "Open Thread" thread]

Coby,

How about moving the Mandas - Neil craig off topic discussion off this thread.

Vernon, if you, as you claim:

Do you have any studies that address this? I cannot find any.

you must be lying in your comment in the previous thread where you claimed:

Please, I have read that paper and many more.

http://www.terrapub.co.jp/journals/JO/pdf/6305/63050721.pdf

I suggest that you actually read it and hopefully you are intelligent enough (tough call I know) but you will see that your questions are answered there. Specifically read the section where the authors showed that under windy conditions the heat from the skin layer is rapidly mixed over the top meter or so.

Intelligence and honesty do not seem to be strong suits in your shoddy hand of cards.

By Ian Forrester (not verified) on 26 Jun 2011 #permalink

Vernon:

Can your position on this be summarized in terms its key implications for the theory of anthropogenic global warming?

I have a number of other questions but first I need an answer to the why-I-should-give-a-damn query.

[comment moved to the "Open Thread thread]

Ian,

Your still unable to converse with anyone that disagrees with your near-religious dogma with out tossing out adhoms.

I read the paper you pulled the first quote off of, then I looked up the source from the paper you quoted. I am guessing you did not look that up. As I stated, it is behind a pay wall but the abstract was as I quoted. The point being, finding a correlation between the water temperature and water vapor over water is not earth shaking. Showing how increased greenhouse gases warm the water would be. Ian, the surface is cooler than the water below it and from the same document, "the skin layer exists even in windy conditions (Donlon et al., 2002)." additionally that publication when on to say "During windy conditions, the variation of SSTskin is almost the same as that of SSTdepth, and SSTskin is a little cooler than SSTdepth and SSTsubskin due to the skin effect and the absence of the diurnal thermocline." So, your basically mixing cooler SSTskin with SSTdepth to warm it with colder water? That is the mechanism where down dwelling LW warms SSTdepth?

Vernon,

Why are you still asking these questions, and as skip has asked, how about you tell us what the point?

Have you even read the nasa paper I provided at post #1, and in what way did that not address the issue?

mandas,

Because as far as I can tell from all the published literature, down dwelling LW does not act over water the way it does over solid land. Everything I have read says it does not, including that NASA paper you provided. Over land the down dwelling LW forces the surface to radiate more out going LW so that TOA remains in energy equilibrium. That does not happen over the ocean, which is my point. I have not seen where this is addressed.

I am not sure what you guys are talking about.

Vernon,

Are you saying that the AGW theory is slightly flawed in that the increase in CO2 that absorbs OLR leaving the surface and then re emitted back down only has an effect on the land? The downward re emitted energy that strikes the oceans merely heats the surface, this heat is then released as WV thus cooling not warming the oceans?

Mandas,

I read your PDF and could not find an explanation for the above, mind you i am not an expert so maybe i missed it (quite possible). If the PDF does describe this in detail can you be a bit more descriptive?

Vernon

A quote from the NASA paper:

".....More than half of the annually-averaged solar energy entering the climate system is absorbed by the ocean (Sellers 1965). The fate of that oceanic heating is illustrated in Figure 3.1. Although the upward flux of longwave radiation from the ocean surface is large, it is nearly balanced by the downward flux from the atmosphere, and the net radiative flux is therefore dominated by solar radiation. Ninety percent of the net radiative heating of the global ocean is balanced by evaporative cooling, with the remaining ten percent coming from sensible heat exchange
with the atmosphere...."

Now that appears pretty clear to me. There is a balance between the upward flux from the ocean and a downward flux from the atmosphere, with evaporation playing an important role. The numbers are shown in Figure 3.1.

If you want more on the subject, they provide a reference (Sellers 1965), and there is also a reference on Figure 3.1 (Hsiung 1987). I also suggest you have a look at the reference list for the paper - there are a lot more similar sources quoted which might provide the information you are after (or you can look at the references used in the references).

That's how we do a literature search and review - its standard practice in science. Give it a go - I pretty much guarantee you will find what you are looking for.

mandas,

I am sorry but you are not getting the point and I can find no literature that explains how down dwelling LW forces the ocean to warm.

Gee, I have been doing literature searches and so far I have not found what I am looking for and no one has been able to point it out either, sorry but that includes you.

Vernon--fluids, warmed on the surface, mix.
Fluid: convection
Solid: conduction
That's what you're ignoring, the rate of change.
That's why you have not found what you are looking for.
Because you're ignoring it.

Hank,

So you are saying that warming the top of a liquid causes it to move down? That is novel idea and I have not considered that, no wonder I cannot find a paper promoting that.

This of course ignores the fact that down dwelling LW does not penatrate the SST Skin and the SST skin is actually cooler than the water below it, which is in the literature.

Vernon, you are lying again. Lying since you claim to have read the review I linked you to.

If you had actually read that paper you would have seen that, yes the actual skin layer is cooler than the subskin layer but both are warmer than the "sea temperature at depth". This, of course, only happens on extremely calm days. Winds cause these layers to mix and thus the heat created by the LWR in the skin gets mixed into the deeper water. Note this is physical mixing and not convection hence your confusion.

Once again here is the link, please read it carefully:

http://www.terrapub.co.jp/journals/JO/pdf/6305/63050721.pdf

Pay particular attention to Figures 2 and 7.

By Ian Forrester (not verified) on 27 Jun 2011 #permalink

Ian,

Since I answered you in #28, but I guess your reading comprehension is really poor. Figure 7 shows how the models attempt to address the ocean's vertical temperature profile near the surface. It does not address how downdwelling LW warms anything. Figure 2 address how warming in the upper METERS are mixed by wind, however, since you did not comprehend my post in #28 I will repeate what I posted then in the hope that you understand it this time:

[F]rom the same document, "the skin layer exists even in windy conditions (Donlon et al., 2002)." additionally that publication when on to say "During windy conditions, the variation of SSTskin is almost the same as that of SSTdepth, and SSTskin is a little cooler than SSTdepth and SSTsubskin due to the skin effect and the absence of the diurnal thermocline." So, your basically mixing cooler SSTskin with SSTdepth to warm it with colder water?

So how does down dwelling LW warm the ocean?

Vernon, down welling IR warms the ocean by inhibiting its loss of heat to the atmosphere as per my tortured attempt to explain in the OP.

Let me be as understanding of your position as possible and say I think this is in fact an interesting and non-intuitive issue. I also think many people (not all) are not getting what your point is. However, I have a couple of questions that move beyond this grey area.

First question is what do you think happens to the energy that downwelling IR brings to the ocean surface? If as you say, and plausibly IMO, it can not be directly absorbed, where does it go (please trace your proposed path until it escapes to space or is somewhere we can reasonalby be assumed to know the rest on our own)?

Second question is, granting for the sake of argument that you are correct that there is no peer reviewed research directly targeted at the effect of increases in downwelling IR on skin, subskin and subsurface ocean layers, how does this affect the policy relevant aspects of global climate change? Is it therefore not happening? Self-limiting before dangerous? So ill understood that we should just keep pumping carbon into the atmosphere?

Or is it really just an example of complex details still needing to be better understood but not altering the general understanding of climate sensitivity etc?

Vernon

I am getting it - but clearly you are not.

No-one is saying that down dwelling LW radiation warms the ocean. But I have said - as it also says in that paper from NASA and as coby has also said on a number of occasions - that down dwelling LW radiation inhibits the loss of heat from the ocean. The figures and equations are in the NASA study, and are in the reference that is quoted in the NASA paper.

It is really simple. And the more down dwelling radiation, the less the heat loss. But that's just simple physics.

Thats exactly right Paul.

Now we have Vernon stating he can see no evidence to suggest LW down dwelling radiation will warm the oceans but Coby et al are saying it will or it has already begun.

Hello Coby,

Thank your for having this post to discuss this. To begin with, I agree that this is a complexe, interesting, and very non-intuitive issue. The reason I think it is important is because this is one of the complex details, that if is not understood, could prevent us from determine the climate sensitivity with enough fidelity to actually determine what the actual sensitivity is, not just a broad range from "no big deal" to "end of the world." Without establishing what the climate sensitivity actually is there will be no way to make rational choices about the future. Anyway, that is why I think it is important and it seems to be a really interesting problem.

First, in order to have a proper discussion less establish the terminology and some basics, the Greenhouse effect works be absorbing OLW and reradiating a portion back to the surface. Whether you say it inhibibs cooling or warms, both are technically true, so lets not play games with words about this. I agree that is the greenhouse effects works on land, pick the terminology you are like.

Over water it gets more intersting. Fully understanding that volcanic activity, fresh water run off from land, and a few other very minor sources can warm the ocean, the principle source of energy is from is solar SW. Most the energy is absorbed in the first meter but some can reach several hundred meteres. This is pretty much the only way the oceans get warmed and most of this happens in the tropics. There are four ways for the ocean to cool: conduction, convection, OLW, and latent heat.

The ocean surface structure is discribed in the literature as having an interface (the top), skin (~10-20 microns), subskin (~1mm), temperature at depth (~1m), and foundation (~5-10m) to use the proper terminology.

First about OLW and DLW, both only happen at the skin and interface but there is no way to measure the interface with current technology that I have found in the literature.

These are the basics, do we agree on this much? If so, I will go into the interesting part.

Vernon, there is not enough to disagree with in your set up to prevent goin on to the interesting part, please proceed.

I will however state a directly relevant quibble and tangentially relevant objection just for the record. The quibble is that "warms" and "prevents cooling" actually is a bit more than word games given the level of detail we are trying to unravel, we may need to return to that. The objection is that climate sensitivity can be constrained by things other than detailed modeling, most importantly by using our best understanding of past climates. I personally think this provides some of the strongest evidence of ~3oC for 2x CO2.

That said, have at it...

I am a little surprised that we are having this conversation. I had thought that the fact that down dwelling radiation cools the oceans is well established. The reason is simple: it promotes evaporation. However, this is not the end of the matter. In an earlier post, Coby asks the reasonable question, what happens to the heat? The answer is that when the evaporated water condenses and forms globules the latent heat is released into the atmosphere. Down dwelling radiation does not inhibit the loss of heat from ocean, as Mandas proposes. In fact, it has precisely the opposite effect.

However, I am surprised that there appears to be nothing in the literature on so fundamental a point. Am I missing something? Is my analysis wrong?

"...the fact that down dwelling radiation cools the oceans is well established. The reason is simple: it promotes evaporation."

Not so fast. Before we go any further, we have to be certain of all the factors in that 'equation'. The molecules that do gain enough energy to escape surface tension are very much in the minority - the ocean surface doesn't just evaporate the whole of its skin at a time. What about all the other molecules at the surface of the ocean that have gained energy, but not enough to change state and escape the surface?

What effect does the changed energy state have on that much larger aggregation of molecules? They've gained energy (from some form of radiation) but not enough to change their liquid state. The usual physical expression of that situation is an increase in temperature.

No?

snowman

'....However, I am surprised that there appears to be nothing in the literature on so fundamental a point. Am I missing something? Is my analysis wrong?...."

Yes. Read the NASA study I linked to in post #1

You're right, Adelady, when you declare that not all molecules gain enough energy to escape the surface tension. However, those that do draw their energy partly from from collisions with others. Thus the net effect is a loss of energy and a cooling of the oceans. Columbia University in its lecture notes on the subject says the following:

'Much of the radiation from the atmospheric gases, also in the infrared range, is transmitted back to the ocean, reducing the net long wave radiation heat loss of the ocean. The warmer the ocean the warmer and more humid is the air, increasing its greenhouse abilities. Thus it is very difficult for the ocean to transmit heat by long wave radiation into the atmosphere; the greenhouse gases just kick it back, notably water vapor whose concentration is proportional to the air temperature. Net back radiation cools the ocean, on a global average by 66 watts per square meter.'

It is easy to be misled by this and to seize upon the phrase 'reducing the net long wave radiation heat loss of the ocean'. The point, however, is that energy is then lost through evaporation, and not by direct radiation. The conclusion is that it all boils down to a loss of energy of 66 watts per square metre (or meter, as the Americans say). Again, I think the mechanics of molecular collision are well known and uncontroversial.

Mandas, the study you refer to does not seem to address this point.

Hank: "Vernon--fluids, warmed on the surface, mix.
Fluid: convection
Solid: conduction"

Fluids also have conduction.

It's just that convection in a fluid or gas with a negative potential temperature gradient is much higher than conduction.

"Thus the net effect is a loss of energy and a cooling of the oceans."

Except that a cooler ocean (and since water vapourises at 100C, the vapour IS hotter than the ocean) will condense water vapour out of the air and its deposition will dissipate the latent heat into the water body and warm it.

And a warming ocean still doesn't lose more H2O as vapour than it's increased energy content as heat allows. Therefore the ocean REMAINS warmer, just not as warm as it would without evaporation taking place.

'sfunny how denialists and other half-wits always leave out large sections of inconvenient truth, yet complain bitterly about how AGW hasn't taken EVERYTHING into account.

Isn't it.

"I am sorry but you are not getting the point and I can find no literature that explains how down dwelling LW forces the ocean to warm."

It doesn't force the ocean to warm. It warms the ocean. As in "if the LW downwelling were not there, the ocean would be cooler". As in "if you walk outside on a cold night with a coat on, you'll be warmer than you would be in a t-shirt".

LW radiation is absorbed by the ocean.

It warms the ocean.

A warm ocean emits LW radiation upward.

That cools the ocean.

Net cooling is less with the GHG present creating more downwelling LW than without it.

YOUR persistence seems to be merely a restating of the G&T paper "proving" that there is no greenhouse effect, merely dropping it being impossible on land.

Coby,

Sorry for the delay, but I have had a bug the last few days and just making it to work is about all I have been up to. I will answer in a day or two.

Just read this (a bit behind, yes), and a few things bothered me, so here's my non-expert take...

First, terminology. The literature apparently uses "coolings" and "warmings" to refer to fluxes leaving or entering the system; don't think of it as temperature change--only the sum of all the relevant energy fluxes corresponds directly to a temperature change. A lot of confusion seems to be about this, and the apparent paradox that the easiest way to shed more energy is by getting hotter.

So lets follow the energy flux; using the numbers and such from the discussion thread, we have 340 W/m^2 at the top of the atmosphere, with about 170 W/m^2 absorbed at depths typically a few meters in the ocean. This energy is re-radiated as long wave IR, and is almost immediately reabsorbed--water is a greenhouse liquid, so the mean free path for LW is tiny. This is essentially a diffusion problem, where most of the LW goes to heating the water around the absorption depth (which is why the SST is relatively warm). The LW that actually escapes to the atmosphere is emitted near the surface, and its spectrum reflects the temperature of the "skin" and "subskin" SST, not the SST at depth.

The surface typically radiates 390 W/m^2 of short wavelength IR, of which about 324 W/m^2 returns as back radiation. The 66 W/m^2 difference is the cooling capacity of LW escaping to infinity. Since increasing GHGs increases back radiation, this cooling capacity becomes smaller with increasing GHGs. For the oceans, the back radiation will be absorbed at about the same depth it radiated at--the mean free path doesn't care about direction--so that part is actually fairly analogous to what happens on the surface of the earth, though the part that determines the effective surface temperature is different, and the equilibrium more complex.

When the ocean skin loses cooling capacity from LW radiation due to increasing GHGs, it has to offset it, primarily by increasing evaporation, but also by increasing outgoing LW radiation. To do either the skin has to get on average warmer--the molecules that evaporate, the ones that "get away", are the tail of the kinetic energy distribution; to increase the population in the tail, the entire distribution has to move up. Hot water loses more energy from evaporation than cold does--is that really in dispute? However, increasing the skin temperature decreases the cooling capacity available to the SST, due to reduced heat diffusion rates and reduced convection--so the SST has to get warmer to compensate.

By Dan Riley (not verified) on 04 Jul 2011 #permalink

All the peer reviewed papers I can find agree that the net down dwelling longwave radiation on the ocean surface leads to an global average of -66 wm2 which is cooling. (I have no desire to publish a list of papers for those to lazy to do their own research.)--Vernon

The 66 W/m^2 difference is the cooling capacity of LW escaping to infinity. Since increasing GHGs increases back radiation, this cooling capacity becomes smaller with increasing GHGs. -- Dan

Dan, your post is very dense and I think I get it for the most part, and everyone is using this number as a given and I am willing to accept it. But I genuinely want to get to the bottom of its origin. If its a stupid question I am willing to look stupid.

The only documentation I have seen of it was in the lecture notes Vernon cited, which were based on a graph of the whole atmospheric-oceanic energy budget from--as far as I could tell--the IPCC Second Assessment Report. It was not referencing outgoing LR radiation from the ocean exclusively--*as far as I could tell*.

Again if I look dumb, fine. I have no problem admitting when I don't get something. But where the bloody hell does this --66Wm2 figure come from in the "peer reviewed literature" in the first place?

If everyone else is floating along fine, my congrats, but it would really anchor my ability to follow this discussion if someone would resolve this for me.

Humor me, please.

Happy Independence Day, all.

skip

As I have been trying to say all along, the link I provided at post #1 (yeah I know - right at the very begining) has all the information on this issue.

Here's the link again:
http://eospso.gsfc.nasa.gov/science_plan/Ch3.pdf

Click on it, then go to the fourth page (it's page #118 in the document) and have a look at Figure 3.1. There are all the relevant numbers. You will note that the amount of ingoing and outgoing radiation varies with latitude, and hence the net radiation flux varies with latitude (its positive to about 20 degrees).

Then, if you are really interested in more info, the source for the data is cited (you know, just like in real science). The source on the figure is Hsiung 1986 - and if you then scroll to the end of the paper you get this:

Hsiung, J., 1986: Mean surface energy fluxes over the global ocean. J. Geophys. Res., 91, 10,585â10,606.

If you type that into Google scholar, you get this link:

http://www.agu.org/journals/ABS/1986/JC091iC09p10585.shtml

So - as I said right at the very beginning of this thread:

"...If someone truly wants to understand this issue, then this link provides some reasonable reading..."

Is there anything else I can help with?

No, thanks.

Let me check this out and sorry for missing it before.

Not having a go at you there skip. I tried to point this out to several people who were asking questions and trying to make points on this issue - but I guess the reading of science is not a common trait among many posters around here.

Skip, try this diagram:

http://www.cgd.ucar.edu/cas/abstracts/files/kevin1997_1.html

for energy fluxes.

Dan:

"only the sum of all the relevant energy fluxes corresponds directly to a temperature change. A lot of confusion seems to be about this"

Manufactured confusion. Keeping a "debate" alive by "misunderstanding".

"The 66 W/m^2 difference is the cooling capacity of LW escaping to infinity."

The problem here is that that 66 is just a difference between two radiative components. You're forgetting the convection and evaporation. They get a look-in too.

Oh, and a short version of the "problem" with that -66W/m^2. See the graph here:

http://scienceofdoom.files.wordpress.com/2010/08/energy-budget-trenbert…

(note: science of doom has done several posts explaining the graph too)

Figures in W/m^2

Solar radiation absorbed by surface: 168
SW radiation absorbed by surface: 324

Total absorbed: 168+324 = 492

SW emitted by surface: 390
Convection losses by surface: 24
Evaporation losses by surface: 78

Total lost: 390+24+78 = 492

Absorbed = Lost

No lost "-66W/m^2"

Swap LW for SW. The radiation from the atmosphere is Infra-Red, the radiation from the atmosphere is likewise IR.

There was some discussion with snowman regarding coral reefs on another thread (I can't remember which one) before he crawled back under his rock. He spouted the standard denialist dogma about there being no climate change, but if there was it wouldn't be a problem etc.

I would like to draw everyone's attention to probably the scariest paper I have ever read, here:

http://siteresources.worldbank.org/INTCMM/Publications/21706633/HoeghGu…

The paper is supported by this statement from Dr. Ove Hoegh-Guldberg, one of the authors of the paper and Professor of Marine Studies and Director of the Global Change Institute at the University of Queensland. He is one of the world's foremost experts on coral reefs. In an article about the state of coral reefs around the world, he stated:

"...The current distribution of carbonate coral reefs around the world today is associated with concentrations of carbonate ions of 200 µmol per kilogram water or more. In this case, there is a natural gradient towards reduced carbonate ion concentrations and more acidic oceans at higher latitudes. This is primarily due to the fact that cold water can contain a lot more carbon dioxide. The significance of this threshold for carbonate ions is that these are the concentrations that you get in tropical oceans when carbon dioxide increases above 450 ppm. Given that these levels of carbon dioxide in the atmosphere are likely to be associated with at least a 2°C increase in sea temperature, it appears that coral reefs will largely disappear if atmospheric concentrations of carbon dioxide exceed 450 ppm....."

Take careful note of that - he is suggesting that even under the conditions that we are currently aiming for to contain climate change - and which we are unlikely to achieve unless things change very quickly - then coral reefs around the world will all but disappear. If this is true - and the work is supported by a number of other studies so it appears to be valid - then the consequences over the next hundred years or so are not just going to be bad, they are going to be unimaginably catastrophic.

This is not just about tourism and nice places to see, if corals disappear the whole ocean ecosystem will collapse. Think about that for a moment. Then think some more. Then start worrying.

Yup, got my powers mixed up! That should have been 25 billion tons.
There are a large number of water usage sites which give estimates for various activities:

Evaporation from reservoirs: 275cubic km/yr
(275 billion tonnes)
World industry: 90 cubic km/yr.....90 billion tonnes
(which includes the world's 63,590 power stations)
Agriculture 1870 cubic km/yr ( listed as evapotranspiration as they can't tell the difference)
So a reasonable estimate for AWV added to the atmosphere is 2200 billion tonnes a year which otherwise would not be there. Which is a lot more than the CO2 added.

By Surgical Blog (not verified) on 14 Jan 2012 #permalink

> A study of satellite data on clouds and water vapor indicates that prior predictions of substantial Global Warming are wrong.

Really? Several other studies show they're right.

> The study introduces a new method to diagnose the total radiative feedback parameter.

So it's new. Why is it right?

> A completely independent analysis reveals that there is insignificant net positive feedback.

Yeah, you're pretty gullible, aren't you.

GTB:

Can you at least cite your source(s)?

So a reasonable estimate for AWV added to the atmosphere is 2200 billion tonnes a year which otherwise would not be there.

So before the reservoirs were built and the farms were irrigated it was all just barren desert? What is the mean residence time for water vapour in the atmosphere?

By Richard Simons (not verified) on 17 Jan 2012 #permalink

waooooo there are scientist all around.. nice ;-)

By Technogies (not verified) on 19 Jan 2012 #permalink

*What* are you?

hey skip are you a reader or a blog admin because your comments are all around this blog?

Surgical Blog, Global Technology Blog, etc seem to be bots cutting and pasting from can.mailarchive.ca for December 2008.

By Richard Simons (not verified) on 23 Jan 2012 #permalink

It seems to be a pretty good one, even addressing other posters by name and being borderline on topic.

If Turing had known how low real human dialogue would sink due to the internet, I think he might have had to devise a better test of AI!

Would it not be better to stop bitching in the last few comments and get back to the main topic of "The Greenhouse Effect in a Water World"

Comments like 'Yup, got my powers mixed up!' were in the original, which is why I think it is not a live person.

Would it not be better to stop bitching in the last few comments and get back to the main topic of "The Greenhouse Effect in a Water World"

Even if you are talking with a machine?

By Richard Simons (not verified) on 24 Jan 2012 #permalink

Yes, Richard Simons, I agree that Comments like 'Yup, got my powers mixed up!' were in the original, which is why I think it is not a live person. Would it not be better to stop bitching in the last few comments and get back to the main topic of "The Greenhouse Effect in a Water World" Even if you are talking with a machine? waoooo, good post!

Hey, it's fun to imitate a machine imitating a person! I'll leave the comments but neuter them...

Yeah everyone - stop bitching!

Miss me while I was away? In case you didn't, I have been travelling and overseas for the past 5 weeks - as well as being in hospital a few times. But it's nice to be home.

Did you disgrace anymore American women on this latest holiday?

Not this time skip. We went to Vietnam and Cambodia, as well as doing some diving along the east coast of Australia. And took my wife with me, so I had to be a good boy.

How was your xmas?

In hospital?

A few times?

You really should look after yourself better - rather than getting all those people to wait on you hand and foot.

Seriously. Hope you're well and staying well.

Hi Adelady,

Yes, I was testing the different state health systems across the country by being admitted to hospital. So far SA is coming a distant third behind Qld and NSW. Had my appendix out in Toowoomba and discovered I have cavernomas in my brain in NSW. Maybe that's my problem.

Hi mandas, I is too bad you are in these problems, but here i want to recommend my post on Surgical Blog related to Brain. may be it will be helpful to you.

As if we'd click on a pointless and probably spam-laden link...