Sorry SR, good try, but what caused it to warm up in the first place ?

The problem with SR's somewhat puerile example is that what is true for beer is not necessarily true for seawater.

When CO2 dissolves in water it forms carbonic acid and comes out of the water when it is heated. If the water is alkaline the carbonic acid reacts with the alkaline and generally remains in solution unless a high temperature is reached.

As the sea is alkaline (pH of about 8.1) the sea usually permanently absorbs the CO2.