When the temperature is constant atmospheric CO₂ is in equilibrium with dissolved CO₂. As shown in the animation on the right, the amount of carbon dioxide in both the atmosphere and in the water stays the same because equal number of carbon dioxide molecules move into the water as move out of the water into the atmosphere.

The amount of gas that can dissolve in water is dependant on the temperature of the water. As the temperature of the water increases the amount of carbon dioxide that can be dissolved by a given volume of water decreases.

As atmospheric carbon dioxide increases it upsets the balance and causes an increase in dissolved carbon dioxide. This is achieved when more carbon dioxide molecules move into the water than move out of the water.

The image on the right shows the overall changes that occur when atmospheric carbon dioxide increases in concentration. Significant increases in amount of substance is indicated by an enlargement of the species.

Notice how an increase in dissolved CO₂ causes an increase in carbonic acid (H₂CO₃ ). In turn this creates an increase in the concentration of carbonate (CO₃^-2 ) ions. Carbonate ions react with calcium (Ca⁺²) ions to produce limestone (CaCO₃).