Please describe the mechanism of how back radiation warms the oceans.
Never a problem. Unlike you, who just ran 3 times from a request to explain his position, I can back up everything I say. That's kind of the point, that deniers can never back up their crazy claims, because their claims are fiction.
First, the Law of Conservation of Energy says you're wrong. Energy can not simply vanish, as your bizarre theory requires. If energy is absorbed by the oceans, it must add heat to the oceans, period.
So, what's the mechanism?
This is the temperature profile of most spots in the ocean. Note the vertical scale is sort of logarithmic.
The bulk of solar energy penetrates deeply and warms the water. Convection causes warmer water to rise, so the oceans get warmer as you get shallower.
However, that trend reverses at the skin layer. The atmosphere is usually colder than the ocean below, so the ocean at the surface loses heat to the cooler atmosphere, which lowers the temperature of the skin layer by about 1C.
The amount of heat flowing out the oceans, from combined conduction and evaporation, depends on the delta-T across that skin layer. Heat conducts from hot to cold, linearly proportionally to the temperature difference. With more of a temperature gradient, more heat flows out of the oceans. Less of a gradient, less outflow.
Enter the IR radiation. It heats the skin layer, decreasing the delta-T across the skin layer, so less heat flows out of the oceans. The IR doesn't heat the deeper ocean directly. It reduces the heat flow out of the deeper ocean, so more heat stays in the deeper ocean, so the IR indirectly warms the deeper ocean.