CIRC is in many respects the successor to the seminal ICRCCM (Intercomparison of Radiation Codes in Climate Models) effort that spanned the late 80's - early 00's. CIRC distinguishes itself from ICRCCM by its emphasis on using observations to build its catalog of cases.

The Intercomparison of 3D Radiation Codes (I3RC) is an ongoing project initiated in the late 1990s.