You would have noticed that whenever you run a long distance or haul a heavy load up the stairs, you are quite out of breath. Actually, that is partly due to increasing carbon dioxide concentrations in the body. This is because when you exert your body, it is forced to respire much faster than it would have when at rest. Now, you must know that a by-product of respiration is carbon dioxide. Hence, if the rate of respiration is faster (as in the above case), more carbon dioxide will be produced for the time. The rate of respiration is increased to keep up the supply of energy to the body. Now, a high carbon dioxide content in blood makes it acidic which, if allowed to accumulate, would disrupt the natural equilibrium of the body. Therefore, all of the extra carbon dioxide has to be eliminated from the body. If more id being produced, more has to be expired and hence, a rise in the breathing rate.
If we talk about the carbon dioxide levels in the air, then too, breathing rates would rise. This is so because if the level of carbon dioxide is high, it would displace oxygen. So, when you breath in once, the air you take in would have less oxygen than normal. Now you need oxygen in the body so to get the same amount as normal, the breathing rate would increase. However, global carbon dioxide levels have not yet increased to such levels that they would affect our breathing rate.
If we talk about the carbon dioxide levels in the air, then too, breathing rates would rise. This is so because if the level of carbon dioxide is high, it would displace oxygen. So, when you breath in once, the air you take in would have less oxygen than normal. Now you need oxygen in the body so to get the same amount as normal, the breathing rate would increase. However, global carbon dioxide levels have not yet increased to such levels that they would affect our breathing rate.