Earth System Grid II (ESG) is a research project sponsored by the U.S. DOE Office of Science under the Scientific Discovery through Advanced Computing program (SciDAC). ESG addresses the challenges associated with enabling analysis of and knowledge development from global Earth System models. Through a combination of Grid technologies and emerging community technology, distributed federations of supercomputers and large-scale data and analysis servers will provide a seamless and powerful environment that enables the next generation of climate research.