August 2015 Update for The Blob

As noted below, I wasn’t ascribing a cause to the warming, only describing a predicted effect of warming whatever the cause.
However, please note that I also don’t subscribe (lots of scribing, here:-) to toy cartoon pictures of the total greenhouse effect, some reasonable fraction of which can be attributed to human generated CO2. The greenhouse effect can IMO best be understood in terms of TOA spectrographs that allow one to — within reason — identify the temperature/height of the emissions from the planet which cool it to balance the mostly SW incoming sunlight that warms it and produce a dynamic equilibrium temperature that is distinct from what one would expect if the planet had no atmosphere and emitted all outgoing radiation from a solid heterogenous surface as approximately blackbody radiation at a local surface temperature. In this view, the ALR plays a key role, as does mere blocking/absorption of LWIR in the active greenhouse bands until the atmospheric density is low enough to permit LWIR photons to escape to space at the temperature of the emission height and consequently at an emission “temperature” in the band that is much lower, usually, than the surface temperature beneath.
So I’m not really concerned with the intensity of the “downwelling IR” at the surface, as this is just part of one of four local mechanisms that couple the surface temperature to the temperature of the atmosphere right above the surface — conduction, convection, latent heat and radiation all four contribute to bidirectional energy transport at the surface. Over the ocean this is almost never in “thermal equilibrium” — something is always heating or cooling, and the ocean and atmosphere just above (meters above) the ocean are almost never in good agreement in temperature — one or the other is warmer or cooler by multiple degrees C much of the year or much of the time, partly because the specific heat and specific gravity of the ocean are both much larger than that of air and so it takes a lot of heat exchange to heat it or cool it and because it takes a lot of force to make it change its pattern of movement (relative to air).
So what warms the ocean? Mostly sunlight. Sunlight is partially reflected and partially transmitted at the surface, and the transmitted fraction is almost all eventually turned into internal energy misnamed “heat”. A warm breeze over a cold ocean might warm the surface a tiny, tiny bit. Extra LWIR from the warm breeze might warm the cold ocean a tiny, tiny bit. But only sunlight is going to warm the ocean to any depth.
What, then, cools the ocean, how does it lose the heat added by sunlight? This is the big question, the one that I think Bob has been focusing on with almost all of his posts. The only means of energy transport from the surface of the sea to infinity (outer space at 3 K) are the usual ones — conduction (to sea bottom, to shore, to the atmosphere — to the physical boundaries of the ocean bulk volume), convection (technically heat transport rather than loss, but conduction plus convection allows a continuous exchange of heat at a boundary via conduction that is then moved away, and of course in the bulk ocean general thermohaline circulation redistributes internal energy/heat so that it forms a major component of the path followed from entry as (probably) sunlight and eventual exit to space, radiation — almost entirely LWIR if one follows custom and subtracts out the initially reflected fraction of SW via “albedo” as a non-blackbody, non-thermal process, and latent heat. Latent heat is a huge one — the ocean surface is nearly always evaporating water (cooling it relative to the air above) or receiving downfalling rainwater (or snow, or sleet) that is water that gave up its latent heat very high up in the atmosphere and is now returning, cooled.
If you look at TOA spectrographs looking down taken over (mostly) ocean water, you still see outgoing LWIR in bands associated with surface temperatures. That is, some of the radiation emitted by the ocean’s surface makes it straight out through comparatively transparent bands in the atmosphere. The air over seawater, however, is usually very humid, and water vapor is a greenhouse gas, so quite a lot of the outgoing LWIR is blocked by water, transferred to the atmosphere, and plays the usual role of moving the temperature of air and water closer together against whatever imbalance they might have. If the ocean is warmer, it warms the air. If the air is warmer, it warms the ocean, in this channel which is not the only channel active and hence may not actually warm or cool as in actually change the temperature in the indicated direction at all. Evaporation cools the water in a pot sitting on the stove, but that doesn’t stop the water from heating when the stove is turned on, it only means that it takes longer to bring it to boil than it might if you put on a lid. In any event, one sees LWIR emission in these bands from much higher, much cooler levels of the atmosphere where it becomes roughly transparent to the emitted radiation, and at these lower temperatures the rate of energy loss is much reduced compared to the rate of energy loss that would have occurred as LWIR directly from the surface at surface temperatures.
That means that independent of the details of energy transport underneath the particular patch of surface you are taking the spectrograph from, there is a greenhouse effect. One that if anything is enhanced by the presence of water vapor per se, although as has been observed and commented on repeatedly, water vapor that cools turns eventually into clouds, and clouds are enormously nonlinear factors in overall heating and cooling as they albedo modulate both incoming and outgoing shortwave (visible light) radiation and longwave radiation, and are large LWIR emitters up high and down low, and eventually they generate snow/rain that falls and cools the entire air column to the ocean or ground surface along the way, acting as “delayed” reservoirs of bulk cooling in between that are often moved long distances laterally (so we get rain in the middle of continents that is the result of latent heat loss from the middle of the ocean).
To summarize, the greenhouse effect at the surface of the ocean exists independent of attribution of warming to “downwelling LWIR. It is implicit in observed TOA spectrographs. It doesn’t “heat the ocean”, any more than the lid I put on a pot on the stove heats the pot, but it can easily alter a dynamical equilibrium temperature of the water heated some other way. Anything that slows net energy transport in a spectral band to eventual loss to space will raise the dynamical equilibrium temperature of a sun heated, open planetary system.