An increase in carbon dioxide concentration makes haemoglobin release oxygen more readily. This is known as

Explanation

Carbon dioxide lowers the pH of the blood, which alters the shape of haemoglobin and reduces its affinity for oxygen, shifting the dissociation curve to the right. The benefit is that the most active tissues, which produce the most carbon dioxide, automatically receive the most oxygen. The chloride shift is the separate movement of chloride ions into the red cell to balance the loss of hydrogen carbonate.