The Model Evaluation Consortium for Climate Assessment (MECCA) aims to: quantify the probable range of future climate change, provide policy makers with information and identify key topics for research. A primary focus of the second phase of MECCA and of the MECCA analysis team is to increase understanding of the uncertainties associated with numerical climate model predictions and to evaluate the propagation of uncertainties derived from predictions of greenhouse-induced climate change through impacts models into policy development. It is possible to identify uncertainty issues which could benefit from additional research and also sensitive points in the policy development process at which uncertainty can be used and abused. Preliminary evaluation of the responses to a survey of project members participating in MECCA Phase 1 reveals, in some cases, experimental designs developed without a full recognition of the needs of impact assessors and policy developers. Increased understanding and more informed debate of all aspects of the uncertainties relating greenhouse-induced climatic change to policy development and implementation will be encouraged in MECCA Phase 2. MECCA and the Analysis Plan Project are aimed at delivering improved understanding of the uncertainties associated with greenhouse-related climatic change.