My Campbell's Biology Textbook says the following:
"For example, when an elk or other mammal moves up into the mountains from sea level, physiological changes that occur over several days facilitate activity at the higher elevations. The lower oxygen concentration in the air stimulates the animal to breathe more rapidly and deeply. It therefore loses more CO2 through exhalation, raising blood pH above its set point.
I was wondering if anyone could explain why blood pH increases as your altitude increases? I know that an increase in pH is a sign of less H+ ions in the blood, but what exactly causes you to lose the ions when you're exhaling CO2?