climatechangeacrosstheglobe(i.e.,thesocialcostofcarbon(SCC),expressedintermsoffuturenetbenefitsandcoststhatarediscountedtothepresent)arenow available.Peer-reviewedestimatesoftheSCCfor2005haveanaveragevalueofUS$43pertonneofcarbon(i.e.,US$12pertonneofcarbondioxide),buttherangearoundthismeanislarge.Forexample,inasurveyof100estimates,thevaluesranfromUS$-10pertonneofcarbon(US$-3pertonneofcarbondioxide)uptoUS$350pertonneofcarbon(US$95pertonneofcarbondioxide)[20.6].ThelargerangesofSCCaredueinthelargeparttodifferencesinassumptionsregardingclimatesensitivity,responselags,thetreatment of risk and equity, economic and non-economicimpacts,theinclusionofpotentiallycatastrophiclosses,anddiscountrates.Itisverylikelythatgloballyaggregatedfiguresunderestimatethedamagecostsbecausetheycannotincludemanynon-quantifiableimpacts.Takenasawhole,therangeofpublishedevidenceindicatesthatthenetdamagecostsofclimatechangearelikelytobesignificantandtoincreaseovertime[T20.3,20.6,F20.4].Itisvirtuallycertainthataggregateestimatesofcostsmasksignificant differences in impacts across sectors, regions,countriesandpopulations.Insomelocationsandamongsomegroupsofpeoplewithhighexposure,highsensitivityand/orlowadaptivecapacity,netcostswillbesig
social cost of carbon discussion