I think it’s a misunderstanding, not a myth.

CO2 influences the greenhouse effect - keeping more solar energy on Earth.

Solar energy gets converted into heat, heat gets absorbed. Some of it gets absorbed by oceans. Some of CO2 also gets absorbed by oceans - their pH decreases. The greenhouse effect doesn’t require great time, but oceanic warming and acidification does require time. Interaction happens on the surface, but the volume is great.

Thus, delays in response are inevitable. Response may also depend on circulation - an ocean current slowing or speeding up.