Greenhouse gases represent about 1% of the atmosphere. CO2 represents between 3 and 4% of that. Man-generated CO2 represents between 3 and 4% of that. NASA's Langley Research Center said that their latest satellite studies showed that CO2 was repsonsible for reflecting more solar radiation into space than is absorbed. Not a problem though, since water vapor has 1800 times more of an effect than all the other greenhouse gases in that 1%. FOr the last 100 years CO2 levels have been at a record low compared to the last 100,000 years that man has been on earth.