Over the last four years two integrated assessment models for global environmental change, IMAGE 2 and TARGETS have been operational at the National Institute of Public Health and the Environment (RIVM). Both models simulate different aspects of global change. A project of harmonization of these models was initiated in 1997. Its main objective was the harmonization of the IMAGE 2 Terrestrial Environment system (TES) and Atmosphere-Ocean System (AOS), with the TARGETS global biogeochemical cycles model (CYCLES). Prompted by the Delft science-policy dialogue workshops, researchers realized the need for an interactive assessment tool for scientists and policy-makers to be able to construct and evaluate emissions scenarios. Therefore the original objective of the project has been changed into developing a special version of the CYCLES model, the so-called meta-IMAGE 2.1 model, which gives model projections for the main climate indicators similar to IMAGE 2.1, but with a run-time of only a few seconds. For the development of the meta-IMAGE 2.1 model, the CYCLES model has been adapted as follows: (i) other values for some of the main model parameters, (ii) a replacement of the ocean submodel by a meta-equation, (iii) a further aggregation of the land-use classes, and (iv) the exclusion of the nitrogen cycle model. These adaptations lead to a new run time of about a few seconds (runtime of the CYCLES model is about 40 seconds, for IMAGE 2.1 about 12 hours).