Carbon dioxide around us
The last gas is carbon dioxide. There is very little of it in the atmosphere, yet it does two jobs — and both are essential.
1 — holding in the warmth
This gas acts to bring the temperature of the earth's atmosphere to a level suited to living things.
2 — making food
It also acts as a raw material in photosynthesis, the process that meets the food requirements of every living thing.
Only 0.03%
By the ordinary composition of the atmosphere, carbon dioxide is present in a percentage as small as 0.03%. Yet that small amount has helped make the earth a place fit for living things.
But an increase is a problem
Global temperature
The rise in the amount of carbon dioxide (CO2) in the atmosphere due to the burning of fossil fuels has become a cause of rising global temperature.
That is, a little CO2 is good — it keeps the earth warm. But the more there is, the warmer it gets, and that is the problem.