Well, I can understand what might be the reason it causes cooling. I have brought this up before.
The IR from CO2 is absorbed in the first few microns of water. That, along with the wind, makes the water more readily evaporate, and cool the ocean surface, and it absorbs ocean heat for the energy to change states. I don't know what the net temperature change is between absorbed IR and evaporation cooling, but this could also be a net cooling, except at times when there is little or no ocean wind.
The ocean is what really controls the earths temperature, because of the most massive of the variables that exchange heat. Variables that heat or cool the ocean are most important.
Now this water vapor does warm the atmosphere, as when it becomes rain, the heat is released into the atmosphere. However, more water vapor means a larger coverage of clouds, which in turn reduce the solar insolation to the surface.
The sun is the most significant source of heat in the earth system. This is why TSI and surface insolation changes are very significant. Tidal and radioactive material heat are insignificant. Greenhouse gasses just hold the heat in, not causing any heat themselves.
Just my hypothesis, but I'm on pretty solid ground there.