Why is a mechanism needed to remove carbon dioxide gas from your cells?

A mechanism is needed because if carbon dioxide were to simply diffuse into our bloodstream to be carried all the way to the lungs, carbon dioxide would dissolve in our blood to form HCO3-, which is acidic and decrease the pH of our blood. This would be fatal for us as our body needs to maintain at a relatively neutral pH. Hence carbon dioxide is removed via hemoglobin from our cells

That result from subduction of oceanic plates beneath lighter continental plates. most of the earth's volcanoes are located around the pacific ring of fire because that the location of most of the earth's subduction zones.