There are two mechanisms taking place. 1) Gases dissolve in liquids (ex: the bubbles in your soda). Unlike the more familiar solution of solids in liquids (like sugar in your coffee) when the liquid temperature increases, gas solubility goes down. So when something raises the temperature of the Earth. the solubility of CO2 in the oceans is reduced and its levels in the atmosphere rise. When temperatures fall, its solubility increases and its levels in the atmosphere fall. 2) CO2 in the atmosphere is a greenouse gas because it absorbs infrared light that all matter emits to radiate heat. That allows it to capture IR emitted by the land and oceans warmed by the visible light of the sun and slow its escape to space. That causes the planet to warm and is known as the greenhouse effect.Net Zero Shock: Carbon Dioxide Rises AFTER Temperature Increases, Scientists Find – The Daily Sceptic
Dramatic new findings from two climate science professors suggest that an increase in carbon dioxide in the atmosphere follows a rise in temperature rather than coming before it and causing it.dailysceptic.org