The oceans are huge! There is a tremendous amount of heat energy stored in them. It takes a tremendous amount of heat energy to change their temperature.
The fallacy is that, if there is warming, there is no way to detect how much of that warming is from human activity. The SUN is responsible for the vast majority of the heat energy reaching the Earth’s surface.
Read The Neglected Sun: How the Sun Precludes Climate Catastrophe.
***The SUN is responsible for the vast majority of the heat energy reaching the Earth’s surface.***
And too many forget that in winter, much of that heat radiates off into space at night.