This articleexaminesthishistoricalcontext andcontrasts twocompeting paradigmsthat emergeda tI IASA in ordert oa ssessa nd respondt ot he carbon dioxideq uestion: The firsta pproachw as relatedt ot he organisation's research projectso nt he future of energy systems, whichd rewo np hysics,e ngineering,e conomics anda pplied system dynamical modeling;t he second approach drew earlierr esearchi ntoe cologicalm anagementa nd complexdynamical systemstheory, andarguedfor theuse of multiple methodstoassess thec arbond ioxide question.T he firsta pproachi nvoked ideaso ft echno-economical controlmechanisms, thesecondresultedinamore embedded framingofclimate change as oneo falarger complexo fi ssuesr elatingt os ustainable development.B ased on resourcesf romI IASA's research repositories andi nstitutional archive, this studyr etraces thesecompeting discourseframingsand outlines thespecificresearchand modeling strategies, policies,and cultural andtechnologicalimaginaries relatedtothem.