Description: Several greenhouse gas emissions scenarios have been developed by the IPCC to determine possible affects on atmospheric greenhouse gas concentrations and related climate warming. The largest estimates show a carbon dioxide concentration of about 800ppmv by the year 2100. Lower estimates rise to 450ppmv by the year 2100. The amount of projected warming associated with these emissions scenarios range from about 2-4°C. Several possible disadvantages and advantages of such a warming are discussed, as well as possible methods to reduce global warming.