This comment seemed like a useful question to discuss, so I’m elevating it to post status
I see ocean heat content discussed here and elsewhere from time to time, but I have never seen a discussion of what causes it to increase. The clear implication is that it is increasing because of warmer atmospheric surface temperatures, but that makes no sense to me.
Surely the small increase in warming of the atmosphere to date could not transfer a significant amount of heat to the oceans. It seems obvious to me the only way that the oceans could accumulate much heat would be through direct heating from solar radiation. If that is occurring, wouldn’t that be direct evidence of a decrease in cloud cover, instead of evidence for AGW?
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Co-incidentally, see here:
http://hockeyschtick.blogspot.com/2011/05/shining-light-on-solar-impacts.html
A common sense question seemingly answered by the one doing the asking. Will we hear discussions on wave lengths of radiation or light; or other explanations that cause us to think of angels dancing on pinheads
So in this case we care about the ability to transfer energy in the form of heat. So the question is, can more heat be directly irradiated into the ocean versus contact-transferred from the atmosphere, or vice versa?
If we assume that the atmosphere transfers more heat into the ocean than sunlight, then we’re essentially saying that the ocean follows the atmosphere. This would mean that the total flow of energy through the atmosphere into the oceans would be larger than the total flow of energy from direct sunlight. This thinking has problems. Just off the top of my head, if the total flow of energy between atmosphere and ocean is larger than between sunlight to ocean then we’re saying the energy transfer through the atmosphere is larger than the direct sunlight to the ground. If this were the case, why would anyone seek the shade of a tree on a sunny day? Humans are mostly water, and if the flow of energy through the atmosphere (the air surrounding you) is greater than sunlight, why do you seek shade to cool down?
Warm air or sunshine could be warming sea water, but notice that both would happen near the surface. Neither air nor light penetrate deeply. Air will more quickly exchange heat when there is wind, whether through flat surface contact or the much faster effects due to turbulent wave action. Wind which is generating foam would increase reflectivity and reduce solar heating.
However, how would evaporating water affect the balance of heat?
That’s a very good point, one that we have been puzzling over since the direct link between PDO-AMO and climate became apparent. In 1977, the Northeast Pacific had a cool PDO. In 1977, the PDO switched abruptly to warm and global climate began to warm immediately. Clearly the ocean did not warm because of warming atmosphere (it was actually the other way around). In 1999, the PDO switched from warm to cool, bringing the 1978-1998 warm event to a close. We obviously don’t yet understand why these things happen so rapidly. Might be nice to spend some of those billions of dollars now going to CO2 research to find out more about the real cause of climate change!
Exactly.
Change cloudiness to change albedo and energy input to the oceans.
Change the air circulation systems to change cloudiness.
Change the vertical temperature profile of the atmosphere to change the air circulation systems.
Change the ozone quantities in the atmosphere differentially at different levels to change the vertical temperature profile.
Change the mix of wavelengths and particles from the sun to alter the ozone quantities differentially at different levels.
Unless someone has a better idea ?
I’m not going to propose any causal relationships,
but measured trends show a decrease in relative humidity, and increase in specific humidity and an overall long term (> 15 year) trend in global temperature.
You start with some warming which causes more water vapor which causes more warming, and evidently this causes decreased relative humidity which means less clouds which could cause more direct ocean warming due to solar irradiance.
The reason it doesn’t runaway is Temperature to the fourth power relationship in the blackbody equation.
And it doesn’t matter what caused the warming in the first place.
Atmospheric CO2 absorbs radiative heat energy coming from below that would otherwise go out into space quickly. The CO2 re-emits this energy – half of which goes back down. The oceans absorb much of this. This extra energy heats the oceans and will eventually heat the atmosphere and will eventually go back out into space. The larger lag time from when the energy comes in to when it goes out into space determines the total increase in the Earth system’s thermal equilibrium energy. (How the warming distributed in the Earth system is complicated.) At least this is my non-expert understanding.
Some ocean warming is also occurring because of decreased ice cover in the summer Arctic.
Well, I have to agree 100% . The Air just cant warm the water in that manner. Otherwise the oceans would be much warmer all the time.
Hmm, interesting question. A few points.
(1) For ocean heat content to increase then more energy has to be retained in the Earth system than lost. In principle this could be either through more incoming solar radiation or through less outgoing longwave radiation.
(2) The models – I know, but stick with me – suggest that the response of ocean heat content to a radiation imbalance is slow, taking hundreds of years to reach an equilibrium. It seems to me that this is consistent with the questioners observation that:
“Surely the small increase in warming of the atmosphere to date could not transfer a significant amount of heat to the oceans.”
This is one reason why the process is so slow.
(3) I don’t know whether anyone has compared how fast the [model] reaction time is to an increase in solar radiation compared to a decrease in outgoing longwave radiation. So I don’t know whether it would actually be faster [in the models] as the questioner assumes it is in real life.
One thing I would say is that a lot of solar energy bounces right off the ocean surface, particularly when incident at a shallow angle [think of the sun’s reflection off a body of water], so it’s not obvious to me that you would expect this to be an easier way of warming up the ocean.
For starters, that positive anomaly they are showing for the Caribbean..
…is really negative
http://stevengoddard.wordpress.com/2011/05/11/romm-and-masters-record-warmth-means-below-normal/#comments
I agree 100%! We have no idea how much heat is being pumped into the oceans from underwater volcanoes and rifts. We have no idea how much heat is being dumped into the oceans from river run off. We have no idea how much heat is produced by energy release in wave action.
Conversely, we don’t really have a handle on the heat loss to evaporation (which changes dramatically depending on both temperature and wave action).
We don’t have a handle on the mechanisms for heat transfer over long and short periods.
I for one have never seen a calculation that proves the El Nino (hope I got the warm one here) can be generated from sun and atmosphere alone. The volume of water and joules required to raise that volume 1°C would indicate to me there is a underwater geological component that can be augmented by solar radiance increases (which is driven by cloud cover and precipitation over the surface area – not solar output).
My opinion has been our climate is driven by plate tectonics more than anything else, at least in the Pacific basin.
There are three ways I see air temperature transfer to the oceans, two of which are reasonably efficient:
1) direct thermal conduction through contact (poor),
2) a turbulent contact, i.e. waves breaking (moderate)
3) rainfall (good).
Worldwide precipitation is estimated at over 1100 mm/yr, though the oceans only rise by 1.8 – 3.2 mm/yr. There is something like (I forget the ratio) 9 cycle times over land, that is the rain that falls evaporates and falls >9 times before reaching the sea, where it evaporates and falls again. Each time energy is taken from the air and put into the water. So rain “washes” the heat out of the atmosphere. (This only occurs because there is still a cooler ocean below.)
Hah! Maybe a rain/snow temperature record would show the downward movement of heat. Or not.
Do sunspot cycles have any standing as an agent of causation with this forum?
Asking in all seriousness – I’m not deep into the science here.
d(^_^)b
http://libertyatstake.blogspot.com/
“Because the Only Good Progressive is a Failed Progressive”
If scientists assume that cloud cover hasn’t changed significantly and if solar output hasn’t changed significantly while ocean heat content is changing, then they will find a way to explain heat transfer from the atmosphere to the ocean since it is the only remaining option.
If you assume heat transfer from the atmosphere to the ocean must be small, then you have to find an explanation for ocean heat content changes – which only leaves changes in cloud cover.
Unless ocean heat transfer from the atmosphere or cloud cover changes can be accurately measured, neither is more likely to be true than the other.
AJStrata says:
May 11, 2011 at 8:04 am
I agree 100%! We have no idea how much heat is being pumped into the oceans from underwater volcanoes and rifts.
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In addition, we have no idea when each of these rifts have opened, or whether their flow rate is variable, or whether we’ve identified them all.
What would be the most effective system to heat domestic water, solar water heating system or an air source heat pump?
The ocean is heated by the sun, which can penetrate down through the ocean to depths of up to 100 meters. The ocean cools at the surface through a combination of evaporation (moist convection) and long wave IR (LWIR) emission. There is a ‘balance’ at the surface between the downward LWIR emission from the atmosphere and the upward blackbody LWIR emission from the surface, so the net LWIR emission is about 50 W.m-2 in round numbers. The evaporation increases significantly with ocean surface temperature. Long term average ocean evaporative cooling fluxes can reach 140 W.m-2. However, the evaporation and the LWIR exchange occur very close to the surface, within the first 100 micron or so over most of the LWIR region. Thiat is about the width of a human hair. Over the last 200 years, a 100 ppm increase in atmospheric CO2 concentration has produced an increase in ‘clear sky’ downward LWIR flux of 1.7 W.m-2. This is ‘buried in the noise’ of the wind driven surface evaporation.
The ocean can only cool at the surface. There are three ocean layers that form as the sun heats the ocean. There is a very thin ‘skin layer’ that is cooler that the bulk ocean surface temperature. This is where the evaporation and LWIR cooling take place. Below this there is a uniform diurnal mixing layer. The cooler water from the surface diffuses downwards (sinks) and produces a uniform temperature layer that varies in depth with season and latitude. The third layerbelow this, typically 50 m to 100 m is where the solar heat accumulates. A temperature gradient builds up during the spring and summer. As the solar heating diminishes in the fall and winter, the diurnal layer depth increases and ‘takes out’ the thermal gradient layer underneath.
However, near the equator, the depth of the mixing layer is insufficient to remove the accumulation of heat below about 50 m. Heat is stored over long periods of time and gives rise to the ENSO oscillation etc. The details get complicated and are not very well understood. This is in part because of a lack of data and partly because this is not part of the usual global warming dogma.
Small changes in the solar constant, of the order of 1 W.m-2 are sufficient to cause major climate change as this heat accumulates in th ocean over long periods of time. For example, 0.4 W.m-2 is sufficient to melt the ice from the last ice age – coupled into the ice sheet over 10,000 years.
There is a more detailed description at Energy and Environment 21(4) 171-200 (2010) and on my website at http://venturaphotonics.com/GlobalWarming.html.
(Hope this helps)
Alistair Ahs’s point #1 is correct: it’s the net energy accumulation that matters. The presence of the radiative imbalance at the top of the atmosphere is an indication that the sea surface has not warmed up sufficiently to match the forcing.
Ocean floor volcanoes, geothermal heat transfer, and ocean current changes could have an impact also.
Heat from ocean-floor vulcanism is totally unmeasured and can go unnoticed, as did the 10 km2 pyroclastic flow at the Gakkel ridge in the Arctic ocean, which was only discovered after the fact in 1999. All reports I have seen on ‘Arctic thaw’ have neglected this unpredictable and impossible to model event.
Add the refractive index too. I don’t know the RI of water off the top of my head (it is roughly 1.54 for quartz), but there will be a critical angle where the sunlight also reflects off of the water instead of penetrating it. Add that to the equations too. Expect heating to increase significantly as the sun transitions to an angle where it is no longer reflecting from the surface. That might be your isolating stat for the difference between heating by air vs heating by solar irradiance directly. Somewhere in the northern temperate zones there should be a place that transitions like this in the fall and spring?
OK, how about a dumb idea?
Ever see a liquid in a jar with two layers of nearly equal density? You can set up motion in the lower layer that moves with a strangely slow periodicity. Of course, you can describe this behavior perfectly with physical laws, it’s just that we don’t usually see things like that. Now imagine a similar oscillation in warm/cold layers of the Pacific Ocean (and others). With a large bowl, the oscillations could be very slow, and there might be a mix of deep waves of different frequencies and directions.
What do we see with ENSO? It looks like upwellings of cold water, e.g. Humboldt from Chile/Peru/Ecuador. I find it hard to believe that the surface temperatures are driven primarily by surface phenomena. The temperature patterns on the SST map are very orderly, almost like the wake of a ship. How would a chaotic atmosphere produce such reproducible order? These temperature waves on the surface recur. It looks more like a circular ripple pattern stretched out by ocean current along the equator.
Hey, I said it was a dumb idea.
Throws hands up in the air. This is a complex non-linear mathematically chaotic system. Strange attractors aka Lorenz “owl eyes” plus lots of other stuff come to mind. Model all you want, but this system is exquisitely sensitive to initial conditions and assumptions about the physical processes involved. About all we can say is that Hansen’s tripe is worthless.
I have never seen any good information (maybe someone can point us to it?) to demonstrate that a massive body of water can be heated to any meaningful extent by a diffuse body of air contacting the surface. It is almost always happens the other way around.