In the early years of our planet, earth was hot, it was a cluster of asteroids, and was constantly being bombarded with them. earth started to cool down and millions of comets are thought to have filled the oceans.
Answer: The early earth environment was having hydrogen in abundant amount. the early atmosphere was full of methane, ammonia, hydrogen sulfide and water. Today the atmosphere contains 0.03% of carbon dioxide in the environment which was higher in the early days of life. There was no life because of less amount oxygen in the environment.
Now the environment is full of oxygen and has less amount of carbon.
