View article

To the Editor—We agree with the point made in a recent Editorial in this journal1 that the assumptions behind models of all types, including integrated assessment models (IAMs), should be as transparent as possible. However, it is incorrect to imply that the IAM community is just “now emulating the efforts of climate researchers by instigating their own model intercomparison projects.” In fact, model comparisons for integrated assessment and climate models followed a remarkably similar trajectory. Early general circulation model (GCM) comparison efforts2 evolved to the first Atmospheric Model Inter-comparison Project (AMIP), which was initiated in the early 1990s3. Atmospheric models developed into coupled atmosphere–ocean models (AOGCMs) and results from the first Coupled Model Inter-Comparison Project (CMIP1) became available about a decade later4. Results of first energy model comparison exercise …