I'm not sure what your position is.

If you think that the greenhouse effect is real (CO2 contributes to warming), why would human emissions not have any effect? we currently emits tons of it per year and person for a substance only in the 400ppm range-- even if you split a single humans emissions over a whole cubic kilometer it makes a substantial concentration difference already.

> It’s entirely possible that sea temperature rise is a result of geologic processes at or near the sea bed, and when you warm a liquid dissolved gasses are liberated.

No, this is not remotely plausible, because we have a pretty solid understanding of how much heat is transferred from the earths interior (see https://en.wikipedia.org/wiki/Earth%27s_internal_heat_budget), and this is completely negligible (and off by many orders of magnitude) compared to the oceanic warming that we already observe (for a 0.5K increase in oceanic surface temperature you'd need thousands of times the total heat that we get from the planet itself).