This paper shows how recently developed features of the performance analysis tool Scalasca helped gain important insights into the performance behaviour of state-of-the-art climate codes in the CESM (Community Earth System Model) ensemble. Particular emphasis is given to the load balance of the sea-ice model and the scaling behaviour of the atmospheric model. The presented work is a result of the project Enabling Climate Simulation at Extreme Scale, which has been funded through the G8 Research Councils Initiative on Multilateral Research Funding
