Why is the increasing amount of carbon dioxide being taken up by the oceans a cause for concern?

• A. The buffering action of carbonic acid (H₂CO₃) causes the pH of seawater to rise.
• B. More carbon dioxide causes an increase in carbonic acid (H₂CO₃), which leads to an increase in the concentration of carbonate ion (CO₃^2–).
• C. There is no cause for concern. Carbonic acid (H₂CO₃) is an excellent buffer and will help keep the pH of seawater constant.
• D. More carbon dioxide causes an increase in carbonic acid (H₂CO₃), which leads to a decrease in the concentration of carbonate ion (CO₃^2–).