Theprincipleof"commonbutdifferentiatedresponsibilities"isthecornerstoneoftheUnitedNationsFrameworkConventiononClimateChange(UNFCCC),formedin1992andnowratifiedby192countries.

　　Theprincipleservesasanimportantreasonwhytheworld'scountries,allwithmanydifferencesintheirrespectiveinterestsandconcerns,couldsitdowntogethertonegotiateasolutionforthepressingissueofclimatechange.

　　Theword"common"showsthatfightingclimatechangeisanobligationforeverycountryaroundtheworld.

　　Undoubtedly,whentheearth,mankind'scommonhomeland,isfacingacrisis,peoplearoundtheglobemustworktogetherandhelpeachothertofindasolution.

　　However,letusnotforgetthattheresponsibilitiesarenotonly"common"butalso"differentiated."

　　Theindustrializedcountries,withabundantfinancialresourcesandadvancedtechnologies,shouldshouldertheirhistoricalresponsibilitiesandmaketangiblemovestodealwiththeirhighpercapitacarbondioxideemissions.

　　Asforthedevelopingcountries,"economicandsocialdevelopmentandpovertyeradicationarethefirstandoverridingpriorities,"theconventionsaid.

　　Takingintofullconsiderationthedifferentsocio-economiccontexts,historicalresponsibilities,andpercapitaemissionsofvariouscountries,theconventionstipulatesthat:developedcountriesshouldtaketheleadincombatingclimatechangeandprovidefinancialresources,includingthetransferoftechnology,fordevelopingcountries.

　　Withthefundsandtechnologicalsupportprovided,developingcountriesneedtoadoptmeasurestomitigateandadapttoclimatechange,accordingtotheconvention.

　　In1997,thethirdsessionoftheConferenceofthePartiestotheUNFCCCheldinJapanadoptedtheKyotoProtocol,which,forthefirsttimeinhistory,madetheprincipleof"commonbutdifferentiatedresponsibilities"becomealegallybindingcommitment.

　　TheUnitedStates,reluctanttoaccepttheprinciple,hasnotyetratifiedtheprotocol.

　　Duringnegotiationsinrecentyears,somedevelopedcountries,includingtheUnitedStates,haveexpresseddissatisfactionwiththeprinciple,demandingthatdevelopingcountriesalsocommitthemselvestothebindingtargetsonemissioncuts.

　　Why,then,don'tsomedevelopingcountriessuchasChina,IndiaandBrazil,alsomajorcarbonemitters,havetocommitthemselvestothelegallybindingtargetsonemissionscuts?

　　Thereasonisthatthepercapitaemissionsofthosecountriesarefarlessthanthoseofthedevelopedones,andtheyhaveproducedonly"survivalemissions"insteadof"luxuryemissions."

　　Moreimportantly,thecarbondioxidecurrentlyintheatmospherewasmostlyproducedduringtheindustrializationprocessofthedevelopedcountries.

　　Itisworthnotingthatcarbondioxide,theprimarygreenhousegas,hasanatmosphericlifetimeofbetween50to200years.

　　ThatmeansthatthecarbondioxidedischargedbyWesterncountriesduringtheIndustrialRevolutionperiodsome200yearsagostillremainsintheatmosphere.

　　Astheconventionsaid:"Thelargestshareofhistoricalandcurrentglobalemissionsofgreenhousegaseshasoriginatedindevelopedcountries,"and"percapitaemissionsindevelopingcountriesarestillrelativelylow."