Cliff, the Levitus et al study says, "We have estimated an increase of 241022 J representing a volume mean warming of 0.09 C of the 0 – 2000 m layer of the World Ocean. If this heat were instantly transferred to the lower 10 km of the global atmosphere it would result in a volume mean warming of this atmospheric layer by approximately 36 C (65 F). This transfer of course will not happen; earth’s climate system simply does not work like this. But this computation does provide a perspective on the amount of heating that the earth system has undergone since 1955.
The point is, I think, the oceans can and have absorbed a tremendous amount of heat in the last 58 years with a very small increase in temperature and therefore thermal expansion.
Trenberth, in conjunction with Kosaka & Xie note, the movement of this heat to deeper waters has brought about what has been called a global warming hiatus over the past 15 years.
The main image for this post is a representation of a classic Carnot heat engine which converts heat to work as it moves from a hot reservoir to a cold one through the engine. (the first law of thermodynamics)
This is also a schematic for OTEC which too converts surface heat to work.
AGW is mainly caused by radiative forcing due to greenhouse gas emissions. OTEC is zero emission energy and therefore would allow for the natural lowering of CO2 concentrations in the atmosphere. As they decline so too will the accumulation of heat in the oceans and that which has accumulated can be converted to work by the process.
Sea level rise is the main problem. Converting heat to work lowers thermal expansion.
The following diagram was posted by Péter Berényi in response to a SkepticalScience post, Watts Up With That concludes Greenland is not melting without looking at any actual ice mass data – comment 53.
It clearly shows the thermal coefficient of expansion of ocean water at 1000 (dbar) – 1000 meters, which is the depth of the cold water heat sink for an OTEC plant – is half what it is at the surface.
Contrary to your assertion, “The redistribution of the local temperatures using OTEC will not ameliorate sea-level rise,” I submit moving surface heat to a depth of 1000 meters would do precisely that. Furthermore the main driver for sea level rise in the future will be polar melting. Tropical storms are the principal mover of heat towards the poles. OTEC would sap the source of energy of these storms thus lessening their severity and would slow down the migration of heat towards the poles.
Berényi said in his comment, “It is not easy to find a realistic heat redistribution pattern that does not increase sea level while sucking in more heat from above.”
OTEC operates 24/7 whereas the oceans are warmed only during the day and first stopping and then diminishing greenhouse gas concentrations would lessen surface warming.
As to where atmospheric heat is being absorbed, I think the first graphic in this article makes pretty clear where this is happening, mostly near the equator. Further the Levitus study would seem to infer that if the oceans had not absorbed so much heat since 1955 the atmosphere would be considerably warmer.
The shifting of heat to greater depths with a commensurate lowering of the rate of increase of atmospheric warming, seems to me, to be the whole point of the Kosaka & Xie study?