What is the mechanism that causes the oceans to heat in response to increased atmospheric CO2 concentration?

Dave: It's because the diffusion coefficient for heat is very large. The diffusivity of heat in water is a couple of orders of magnitude larger than the diffusion coefficient of a gas, and only a factor or 5 to 10 smaller than the diffusion coefficient of momentum (which is given by the kinematic viscosity). What that means is that when you heat the surface of water with IR light, even though most of the energy is deposited in the very near surface layer (although the penetration depth is on order of 10 to a few hundred microns, depending on wavelength, see spectrum below), heat diffuses fast enough that most of it makes it into the bulk before it comes off again as latent heat in the form of water vapor or a sensible heat flux. This happens even with a quiescent body of water, and if there is a little mixing from turbulence the downward flux of heat from the surface is even more efficient. (The realclimate web page Dook linked to is also good, Peter Minnett is one of the foremost authorities on the ocean surface skin layer.) This property of heat (that it diffuses into water faster than it comes out the surface) is exploited in oceanography using something called the Controlled Flux Technique developed at the University of Heidelberg. You ought to be able to google "Controlled Flux Technique Heidelberg" and some more information on that.

edit2: First off, you have to understand that profile if for low-wind clear-sky mid-day conditions so that the downwelling LW IR radiative flux is relatively small, like 170 W/m^2 (or whatever the blackbody flux is at -40C (which is the effective radiating temperature of a cloud-free sky)) and the incoming SW solar flux is high (probably over 1000 W/m^2. Under overcast conditions regardless of wind speed the temperature profile looks much different and there is no cool skin. The cool skin is also very small when wind speed is high even if the sky is clear. And at night there is no subskin SST max, the temperature profile is uniform until you get to the cool-skin (assuming you have clear skies). Clear on that? Maybe I should summarize:

Condition -------------subskin SST max------------Cool skin

"Clear skies, daytime, low wind"-----Yes ---------------yes

"Clear skies, nighttime, low wind"----No------------ yes

"Clear skies, daytime, high wind"----Maybe--------No

"Clear skies, nighttime, high wind"---No----------Maybe

"Cloudy, daytime, low wind"-------------Maybe------No

"Cloudy, nighttime, low wind"-------------No---------No

"Cloudy, daytime, high wind"-------------No-----------No

"Cloudy, nighttime, high wind"-------------No----------No

The very top "cool skin" is because the latent and sensible heat flux from the ocean into the air occur over the diffusive length scales of heat which are on order of a 100 micrometers (henceforth abbreviated as um since a u sorta looks like a greek mu). So the heat leaving as evaporating water and direct heating of the air above the water cools the water at the very surface. Over the characteristic time it takes for this heat flux to occur, heat can diffuse about 100 um, so the cool skin forms over this layer. The subsurface peak forms because the downwelling SW radiation penetrates to about a meter and heats the water. This forms a stable density stratification that doesn't mix well downwards so the heat diffuses upwards, where the max forms because the surface is cooling.

If there is a lot of downwelling LW IR (from clouds mainly), then that surface heating swamps the latent and sensible heat flux cooling so you don't see the cool skin. The ocean surface is still cooling, but the combined latent and sensible heat fluxes are on order of 200 W/m^2 and the downwelling IR flux is 350 W/m^2 so the cool skin doesn't form. You can still get the subsurface temperature maximum at about a meter so the warm surface layer still forms (in the daytime).

At night, since there is no downwelling SW solar flux, you never see the subsurface temperature maximum, only a well-mixed layer up to about 1000 um in depth at which point you will start to see the cool skin layer (if there aren't any clouds). If it's overcast at night, the temperature is mostly uniform throughout the upper few meters and will cool slowly if the relative humidity is below 100% (so that there is an upwards latent heat flux).

So it's simple (in my opinion anyway) but the figure you link to represents only one possible situation at the ocean surface that happens under a relatively restrictive range of conditions.

A better question for you is that if you put the oceans in contact with a warmer atmosphere, why would you NOT expect them to heat up? Granted the longwave radiation does not penetrate far into the ocean, but if the surface is warmed a thermal wave will propagate downward via the thermal diffusion equation, that's what happens on land. However in the ocean you also have turbulent mixing and subduction, which can transfer the heat from the warmed surface layer downward much faster than what happens on land. Nevertheless, in the short-term the heating is confined to the mixed layer.

I might mention that not only is there evaporation from the ocean surface, there is also precipitation back to the surface. Presumably a warmed atmosphere might have somewhat warmer precipitation, although I have never seen any studies on this.

Um mm, oh dear, here we go again, not sure how many times this has to be explained or how much I can simplify it any further, visible light strikes the surface and is converted to IR (heat) the same principle works in shallow water/seas it can still warm the water in this way, and any one who's ever had a tropical holiday can see the nonsense of your statement that all that energy is lost in evaporation at the surface as water in the tropics is warm to a depth of many meters. But there is also heat transfer from the atmosphere to the ocean and the atmosphere has warmed, water is much slower to change and the effect is very small compared to the atmosphere warming but acting across the entire ocean surface of the planet there is certainly an effect which to date is ~6in which is partly caused by ice melt and partly by thermal expansion.

So unless you now plan to deny thermal expansion as a theory, I'm not really sure where you are going with this nonsense.

As I seem to have to keep saying to deniers please take a science class.

Conduction from contact with air at a different temperature coupled with mixing of water away from the surface. It is the same mechanism that causes lakes to be warmer in the summer than in the winter.

A warmer atmosphere slows the rate at which heat moves from the surface layer to the atmosphere via conduction. So, with the same amount of incoming SW and a slowing of heat loss by conduction, heat content increases.

It's the other way around, warm oceans give off Co2 as they cannot keep it dissolved in a warmer state, this is proven by ice core data, Co2 always lags earths temperature changes by a few hundred years.

Oceans are not static, they are filled with waves and currents which distribute heat, when surface temps become too high storms and hurricanes start and further mix up the oceans and distribute heat to higher latitudes

Climate is an extremely complex and chaotic system, which is why computer models are so poor at predictions.

Good luck. No warmist will be able to answer this without quoting RealClimate or SkepticalScience. Their basic hypothesis is that while CO2 doesn't directly warm the oceans, it's warmth prevents heat loss from the ocean. Kind of like a blanket I guess. Call me skeptical given the heat capacity difference between the ocean and the atmosphere (1,100 times greater for the ocean if I recall ... kind of like trying to warm a 600,000 sq foot warehouse with a 20W heater.)

But to be honest I don't understand the physics and I doubt anyone around here does either.

I believe that a warm ocean would also emit LW radiation and if it is warmed more by the air, it would emit even more LW.

Anyone capable of really understanding and posing such a question is also capable of looking up the real science sources for an answer. For example here: http://www.realclimate.org/index.php/archives/2006...

Or at least looking up his own answer of a few days ago:

http://answers.yahoo.com/question/index;_ylt=AnAc7...

This is a denier-trick fake question. One of many thousands here at the Yahoo Answers Global Warming Deniers-in-Training category.

An often useful way to decode such fake questions from deniers is to go to skepticalscience.com and see which stock anti-science myth is being recycled as another YA denier-training fake question. This looks like a good candidate: http://www.skepticalscience.com/cooling-oceans.htm