Carbon dioxide is essential as plants use it to make food. when does it become pollutant? what damage does it cause cause by?

 Carbon dioxide is a natural component of the atmosphere and is essential for plants in order to carry out photosynthesis. But still it considered as a pollutant because, for the proper functioning of any ecosystem there should be a balance between all the components of the ecosystem.  If any component is more or is present in excess, it becomes a threat to the ecosystem. The same is the case with carbon dioxide. Destruction of forests by humans for industrialization, setting up of factories, pollution by vehicles, burning of fossil fuels etc are increasing the level of carbon dioxide in the atmosphere. Plants and trees absorb the carbon dioxide, but when they are destroyed, carbon dioxide gets accumulated in the atmosphere. Carbon dioxide becomes a pollutant when it is present in excess and become harmful, causing adverse effects on the life of living organism.
 
The damage caused by carbon dioxide in the atmosphere increases the temperature of the atmosphere. This gas allows visible radiation to pass through it but traps the infrared radiations that are reflected by the earth surface. These trapped heat waves warm the earth surface causing green house effect. The continuous warming of earth surface (global warming) disturbs the patterns of climate, weather, and vegetation.