Final answer:
When carbon dioxide levels in the blood increase, the blood becomes more acidic due to the production of more hydrogen ions. This decrease in pH reduces the affinity of hemoglobin for oxygen.
Step-by-step explanation:
When carbon dioxide levels in the blood increase, more hydrogen ions (H+) are produced, leading to a decrease in blood pH. As carbon dioxide combines with water, it forms bicarbonate (HCO3-) and hydrogen ions. This increase in carbon dioxide and decrease in pH reduces the affinity of hemoglobin for oxygen, causing the oxygen dissociation curve to shift to the right.