This is a dishonest comparison. The atmosphere warming has a much more immediate impact and the ocean isn't a perfect heat sink.

Air has a specific heat (~1) less than a quarter per unit mass than water (~4.1). The atmosphere has a mass of ~5 billion kgs and the ocean has a mass of ~1.4*10^21 kgs.

It requires a lot less trapped energy to warm the atmosphere by 1 C than the ocean. We're well on track for 2.5 C increase since preindustrial levels.