Atmosphere is very important for our planet and this is made of a lot of parts i.e. gases.
CO2 is the most important man-made greenhouse gas and it acts like a blanket trapping heat near the surface of the Earth. Fossil fuels such as coal, oil and natural gas are sources of CO2.
The level of CO2 in the atmosphere has been on a rise for the past 60 years and it is still on the rise.
But, wait a minute, is CO2 good or bad. We are saying CO2 is important then how can it be bad.
CO2 is present ,both in the atmosphere and in the oceans (where it is being absorbed and acidifying the waters, with potentially big impacts on marine life). Trees and oceans do a sequestration of CO2. Trees use CO2 and give us oxygen, oceans on the other hand absorb oxygen from the atmosphere but what we are emitting is way to high and there will be long-term consequences that future generations will have to live with.