Evolution of the atmosphere

Question 1

What are earth’s gas percentage

Answer 1

80% nitrogen
20% oxygen
<1% other gases like carbon dioxide and water vapour

Question 2

How did gases enter and leave our atmosphere?

Answer 2

In the first billion years, there was intense volcanic activity which produced lots of CO2 water vapour and nitrogen with smaller amounts of methane and ammonia. The water vapour eventually condensed into oceans and dissolved carbon dioxide to form carbon precipitates and sediments.

Question 3

Major change

Answer 3

About 2.7 billion years ago, algae started to form and green plants evolved a lot in the following billion years. Because there organisms can photosynthesise, it takes in carbon dioxide and produces oxygen which increased oxygen levels and decreased CO2 levels allowed more complex animals to evolve.

Question 4

2nd major change

Answer 4

Algae and green plants could only hold a small amount of carbon dioxide. When they died, they fell to the seabed and were buried in layers of sediment. Over millions of years this compressed and became sedimentary rock, oil and gas, which trapped the carbon.

Question 5

What and how was it formed

Answer 5

Crude oil and gas were mainly from dead plankton. Coals were mainly from dead plant material. Limestone were mainly made from calcium carbonate that marine organisms incorporate into their shells and skeletons.

Question 6

How old is the planet

Answer 6

4.6 billion years