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About 3000 million years ago, CO2 was one of the main gasses in the Earth s atmosphere.
About 400 million years ago, plants and trees grew on most of the land. When plants and trees died they were covered in sand and slowly decayed to form coal
Describe and explain how the composition of the Earth s atmosphere was changed by the formation of coal.
3 Answers
- Tim DLv 73 years ago
The formation of coal meant a lasting (to modern times at least) reduction in available carbon to form atmospheric CO2.
During photosynthess, plants use the carbon from CO2 to build their tissues. But when the plants die, this carbon is usually returned to the atmosphere (combining with oxygen to form CO2).
But when plants are buried, forming coal, the carbon of dead plants is not returned to the atmosphere (at least not for some time--even before coal mining, natural processes like erosion occasionally exposed some of it to air so it could again form CO2).
So generally, the formation of coal (like the rise of life) led to an atmosphere with far less CO2. i.e. semipermanent losses of CO2. Such an atmosphere was far from the "hothouse" atmosphere of the early Earth.
- 3 years ago
Water helped form the ozone layer and create oxygen for plants. As the algae grew the CO2 levels decreased and for the first time the earth was green and oxygen formed. I'm guessing the coal somehow helped oxygen stay the dominant gas on earth.
