What is one harmful effect of increased levels of carbon dioxide in the atmosphere & how it cause this effect?

Answer 1

Green house affect. "and how it cause this effect" makes no sense. Did you mean "and how does it cause this effect? Poeey.

Answer 2

CO2 is mother natures first step in recycling our air. Plants have done a great job . U need to keep an eye on the oxygen. Look at CO2 it has 1 atom of C and 2 atoms of oxygen . So u need to look for a decrease in oxygen it is more important to u.