Today human activities are overwhelming the natural processes that pull CO2 out of the atmosphere.
At the dawn of the Industrial Era in 1750, atmospheric CO2 stood at about 280 parts per million. It has taken humans only 200 years to completely reverse the trajectory begun 50 million years ago and return the planet to CO2 levels not experienced for millions of years.
Most of that shift has happened since World War II.
MarketWatch Oct. 1, 2020