COLUMBIA will be executed under four scientific and one management work packages (WP). WP1 will provide technical support, model data management, and implementation of numerical algorithms for application in WP2, WP3, and WP4. WP2 will perform process-based evaluation of the full model set. Specifically, it will focus on addressing two long-standing scientific questions: (i) how well are the ENSO structure and variability and its observed teleconnections under the historical period represented in ESMs, and (ii) what are the dominant regions and mechanisms governing the variability in oceanic heat- and carbon-uptake in observations and models. WP3 will develop a framework for identifying emergent constraints based on observational data that is not used in WP2. The new constraints will be applied as baseline to determine a model’s weighting scheme. Finally, WP4 gathers information from all WPs and analyse how the key uncertainty and its underlying mechanisms evolve under future forced climate change. In addition, WP4 will synthesize our findings and results on optimized future projections.