Levels of doubt in the science and economics Type of doubt Underlying question Specific challenges doubt re impact questions about existence 1 “Climate c hane or extent is not happenin” Lower 2 “Š armin will be er­ modest” questions about source 3 “Humans are not causin climate chane” questions about impact 4 “…here are bene fits from climate chane” 5 “Damaes from climate c hane will be small or uncertain” 6 “Humans will be able Degree of doubt to adapt” doubt re mitigation response is futile 7 “…here’ s no point in reducin emissions Earth will ƒeep warmin an­wa­” response is costly 8 “…he costs of reducin emissions are er­ hih” response is 9 “Other countries are not unequally shared pla­in their part” Higher ”