1] the significance of uncertainty
there will always be uncertainty about temps in the atmosphere and in the oceans, but i argue that where these uncertainties extend into the deep ocean, there's not likely to be information which compromises the facts of the matter on the ocean surface where data is more reliable.
2] the importance of the surface temps we can more easily measure
the sea surface is where heat is absorbed from the sun, and while it could conduct through its mass to great depth, much of the heat loss is to the atmosphere through convection and enthalpy. this latter factor is all that i see as being very crucial to global warming.
3] the importance of decadal/multidecadal tides to the sea surface temps
since surface temps are warmer and such coincides with the tidal systems' lull in cool-cycle activity, i think there's reason to attribute the warming to these trends which are failing to cycle deeper, cooler water to the surface.
4] the significance of sea surface temps to global warming
granted a warmer surface, the enthalpy - the amount of energy needed to add to the water before evaporation - is lower (the reserve enthalpy is higher). for this reason, the same amount of sunlight can elicit higher amounts of evaporation and convection... greater communication of temperature between the ocean (where we are agreed that most of the earth's heat is stored) and the atmosphere.
5] sea-temp forcing, not CO2 forcing with regard to H2O vapor
this is the forcing argument i put forward. it is supported by the increase in H2O vapor right in line with these tidal anomalies like el nino (that is since the ~1980s):
from the NOAA's ESRL @ boulder, co.
a spike in atmospheric CO2 does not jive in this way... forcing from CO2 is just a theoretical guess rather than a substantiated claim. it cant be shown to produce cause-effect with so few PPM change as had been made in the 70s, moreover since industrialization. not supported.
6] H2O vapor dominates the greenhouse effect
lets examine the chemistry of the GHGs. if CO2 cant likely be implicated as a forcing agent for atmospheric H2O in the way that sea temps can be shown to, can it be said to be a significant contributor in itself as you have pointed out? are all GHGs equal?
i say they are not. H2O vapor is quantitatively the most abundant of all of these gasses and the one which directly coincides with warming trends. apart from that, the H2O advantage is also qualitative. it will simply absorb or scatter more heat than CO2. qualitative and quantitative.
add a few PPM of a scarcely significant GHG, and you dont get real warming. to make that case, one will have to ignore the other contributors which coincide with warming, and attribute the proceeds of those contributors to CO2. yet the glove does not fit.