Why is air a renewable resource?

Answer 1

YESThe air on this planet is not renewable. Much of the pollution and emissions that we pump into the air today will be there for many years. For instance, the lifetime of carbon dioxide, a greenhouse gas, is approximately 4000 years. So the changes that we make to the atmosphere today will be there for a long time to come. Some components of the atmosphere are involved in various cycles, such as water, which is rained out and then evaporates again and again. That happens relatively quickly. Oxygen and carbon dioxide are also involved in the cycle of respiration (plants and animals contribute to this cycle). However, these cycles are in equilibrium, and when humans disrupt this delicate balance, the effects can last a very long time. In that sense air is not renewable.

We can also consider how the air on the planet came to be formed at all. The nitrogen component is not very reactive and has presumably stayed over billions of years. Oxygen however is very reactive, and many minerals contain it, so there is a large amount locked up in the materials of the earth's crust. In the very early stages of the earth there may not have been much oxygen, which was then formed by bacteria in the oceans and lakes. Oxygen is also formed by plants under photo-synthesis. So there are ways for oxygen to be renewed naturally, and as far as we know it has been very stable for thousands of years, despite all man's use of it.