What adds carbon dioxide to the atmosphere?
breathing of humans trees and plants (in night) engines volcanoes The level of CO2 in the atmosphere rises and falls naturally in response to seasonal changes each year. This has probably occurred for several tens of millions of years. What is more serious is an overall, very rapid increase in the “background” level of CO2 that we can trace back to the beginnings of the industrial revolution. The amount of carbon dioxide in the atmosphere is a balance between the things producing it (the “sources:” breathing, burning, decomposition) and the things removing it from the air (the “sinks:” plant growth, mineral formation, dissolving in water). Why does this concentration change seasonally? Because when spring arrives, all the plants begin growing again, and this process uses up CO2 — so during fall & winter carbon dioxide builds up, and during spring and summer this supply is drawn down. But if it is spring in the Northern Hemisphere, then it is fall in the Southern Hemisphere — doesn’t
