The countries should take the following steps to reduce the carbondioxode emissions in the atmosphere.
1) Basically high amount of carbondioxode gas is emitted from vehicles. So if the government reduces the number of vehicles or use those vehicles that are environmental friendly like solar vehicles. So the concentration of carbondioxode will be reduced.
2) Grow such type of organisms which uses the carbondioxode. Such type of organisms are plants. Grow more plants, so the concentration of carbondioxode is reduced.