There are effects both ways, but most of the effects of CO2 concentration on temperature occurred in the 0-100 ppm range (if we ever got that low, there would be no plant growth). Beyond that the temperature increase per unit increase of CO2 rapidly approaches zero because of the logarithmic nature of the effect. Temperature fluctuation due to seasonal variation, variations in insolation, variations in solar output, variations in orbit, etc., have a greater effect on atmospheric CO2 being sequestered in or released from ocean water.