We propose non–linear models to study the feasibility of removing CO2 from the atmosphere by introducing some external species such as liquid droplets and particulate matters in the atmosphere, which may react with this gas and get it removed by gravity. Further, this gas can also be removed by photosynthesis process upon using plantation of leafy trees around the sources of emission. The proposed nonlinear models are analysed using stability theory of differential equations and computer simulations. Model analysis suggests that the concentration of global warming gas decreases as the rates of introduction of liquid droplets and particulate matters increase. Also, this gas can be removed almost completely from the atmosphere, if the rates of introduction of these external species are very large. The concentration of CO2 also decreases as its absorption by green belt increases. It decreases further if the rate of introduction of external species increases. The numerical simulation of the models confirms these analytical results.