Where does CO2 come from? Most of the CO2 on our planet for about the last four billion plus years, comes from the planet itself, just as it continues to today.
Today most of the CO2 on this planet comes from the ocean. Thousands of volcanoes today are under current sea levels causing very high levels of CO2 into the ocean and sometimes many of the volcanoes are above sea level as are many today. If all volcanoes were above sea level, we would all be dead. The oceans filter the volcanoes from the atmosphere. The higher the ocean the higher level of filtration and the cleaner the air, less ash in the air, that would turn lungs into cement.
Most of the atmosphere has always been a direct result of solar evaporation of water ( warm air ) and of course anything and everything in the water will be in the air, like CO2. So for billions of years before any kind of life on this planet, the air has been for the most part all evaporated water and CO2. Then plant life began in the ocean, absorbing the carbon, oxygenating the ocean and then the air, The warmer the air the more evaporation. So if we had no gravity, water or ocean there would be no air or atmosphere to hold the life giving CO2 and oxygen.
After one hundred million years of ice age ending about six hundred million years ago, much of the CO2 during the ice age would have been trapped under the ice and during that time sun light would have been melting ice, separating the water (H2O) the hydrogen from the oxygen, allowing oxygen to rise in to the air creating more atmosphere, while something similar to hydrogen peroxide would flow back in to the ocean. So after one hundred million years of adding oxygen to the air, add all the CO2 trapped under the ice and once again the air is for the most part all CO2. I wonder way there was no global Warming when the earth was covered with ice, for a hundred million years, when the air was all CO2, and the core of the planet was hotter ?
After the first micro-organisms above sea level came to life five to six hundred million years ago. The next thing to come to life, was plants and later trees that breathe in carbon from the CO2 leaving oxygen (02), then millions of years later, life that needed oxygen to breath, crawled out of the ocean, my guess to eat insects and bugs, and since then all life has ended on this planet many times. Today most of the life giving CO2 on our planet, comes from our planet, from the ocean, just like it has for the last four billion plus years and now add the CO2 exhaled from lungs too.
Two oxygen atoms are good for the lungs, three oxygen atoms cause respiratory failure, two oxygen atoms and one carbon atom, come out of the lungs, and cause life for plants and trees, that were here first, making oxygen from the co2 for millions of years, from carbon and oxygen bonded together by heat for billions of years.
Percent of CO2 generated by our planet for the last four billion years ( 99.999999999999999 % )
Percent of CO2 generated by man kind for the last four billion years ( 00.000000000000001 % )
The earth has produced, Trillions of times more CO2 than mankind over four billion years.
The human body is made of water and carbon and requires dioxide to release the energy in our bodies, from the energy in the carbon base food we all eat..