Half life is 12 year. It also rise rapidly in the high troposphere (where the magic happen), so the methane we emit today will have an effect in 2-3 year, where

Half life is 12 year. It also rise rapidly in the high troposphere (where the magic happen), so the methane we emit today will have an effect in 2-3 year, whereas the carbon we emit today will have an effect in roughly 20 year. Today's climate is caused by 2003 emissions.