Is the concentration of Carbon Dioxide in the Earth's atmosphere constant since the planet's formation?

The concentration of carbon dioxide in the Earth's atmosphere has not been constant since the planet's formation. In fact, it has undergone significant fluctuations over geological time scales due to various natural processes.

Initially, during the early formation of the Earth, the atmosphere was likely comprised of a much higher concentration of carbon dioxide, emitted by volcanic activity. As the planet began to cool and conditions stabilized, several processes contributed to the reduction of atmospheric CO2 levels. One of the key processes influencing carbon dioxide concentration is the weathering of continental rocks, which chemically removes CO2 from the atmosphere and eventually leads to its storage in the oceans and sediments.

Additionally, biological processes have played a crucial role; for instance, the advent of photosynthetic organisms led to an increase in oxygen levels and a corresponding decrease in CO2 as plants take up carbon dioxide during photosynthesis. Over millions of years, variations in atmospheric CO2 levels have also been influenced by events such as glaciations and mass extinctions, which altered the balance of carbon sources and sinks.

As a result, carbon dioxide concentrations have ranged from much higher levels in the distant past to relatively lower levels in the more recent geological history, affirming that the atmospheric concentration of carbon dioxide is indeed variable, not constant