Why greenhouse gases heat the ocean

Observations of ocean temperatures have revealed that the ocean heat content has been increasing significantly over recent decades. This is something that has been predicted by climate models, and has therefore been described as a 'smoking gun' for human-caused greenhouse gases.

However, some have insisted that there is a paradox here - how can a forcing [sic] driven by longwave absorption and emission impact the ocean below since the infrared radiation does not penetrate more than a few micrometers into the ocean?