The Chemistry-Climate Model Initiative (CCMI, see was created as a result of the IGAC/SPARC Chemistry-Climate Model and Evaluation Workshop held in Davos (Switzerland) in May 2012. The initial driver for this initiative is the realization that the chemistry and dynamics of the stratosphere and troposphere are now being studied and modeled as a single entity in global models. Consequently, CCMI supersedes the SPARC Chemistry-Climate Model Validation (CCMVal) activity and the IGAC hindcast activity is embedded in CCMI, to benefit from overlapping scientific interests and approaches of the tropospheric and stratospheric chemistry modeling and observational communities. Additional future CCMI activities may include new phases of the Atmospheric Chemistry-Climate Model Intercomparison Project (ACCMIP).