<P> Examples of the atmospheric lifetime and GWP relative to CO for several greenhouse gases are given in the following table: </P> <Table> Atmospheric lifetime and GWP relative to CO at different time horizon for various greenhouse gases <Tr> <Th> Gas name </Th> <Th> Chemical formula </Th> <Th> Lifetime (years) </Th> <Th_colspan="3"> Global warming potential (GWP) for given time horizon </Th> </Tr> <Tr> <Th> 20 - yr </Th> <Th> 100 - yr </Th> <Th> 500 - yr </Th> </Tr> <Tr> <Td> Carbon dioxide </Td> <Td> CO </Td> <Td> 30--95 </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Methane </Td> <Td> CH </Td> <Td> 12 </Td> <Td> 84 </Td> <Td> 28 </Td> <Td> 7.6 </Td> </Tr> <Tr> <Td> Nitrous oxide </Td> <Td> O </Td> <Td> 121 </Td> <Td> 264 </Td> <Td> 265 </Td> <Td> 153 </Td> </Tr> <Tr> <Td> CFC - 12 </Td> <Td> CCl </Td> <Td> 100 </Td> <Td> 10 800 </Td> <Td> 10 200 </Td> <Td> 5 200 </Td> </Tr> <Tr> <Td> HCFC - 22 </Td> <Td> CHClF </Td> <Td> 12 </Td> <Td> 5 280 </Td> <Td> 1 760 </Td> <Td> 549 </Td> </Tr> <Tr> <Td> Tetrafluoromethane </Td> <Td> CF </Td> <Td> 50 000 </Td> <Td> 4 880 </Td> <Td> 6 630 </Td> <Td> 11 200 </Td> </Tr> <Tr> <Td> Hexafluoroethane </Td> <Td> </Td> <Td> 10 000 </Td> <Td> 8 210 </Td> <Td> 11 100 </Td> <Td> 18 200 </Td> </Tr> <Tr> <Td> Sulfur hexafluoride </Td> <Td> SF </Td> <Td> 3 200 </Td> <Td> 17 500 </Td> <Td> 23 500 </Td> <Td> 32 600 </Td> </Tr> <Tr> <Td> Nitrogen trifluoride </Td> <Td> NF </Td> <Td> 500 </Td> <Td> 12 800 </Td> <Td> 16 100 </Td> <Td> 20 700 </Td> </Tr> </Table> <Tr> <Th> Gas name </Th> <Th> Chemical formula </Th> <Th> Lifetime (years) </Th> <Th_colspan="3"> Global warming potential (GWP) for given time horizon </Th> </Tr> <Tr> <Th> 20 - yr </Th> <Th> 100 - yr </Th> <Th> 500 - yr </Th> </Tr>

Which gas accounts for the majority of the anthropogenic greenhouse effect