Front Matter -- Preface -- Acknowledgments -- Contents -- Executive Summary -- 1 Questioning the Effectiveness of U.S. Climate Modeling -- 2 Climate Models, Observations, and Computer Architectures -- 3 State of U.S. Climate Modeling -- 4 Increased Societal Demands on U.S. Modeling -- 5 Responding to Climate Modeling Requirements -- 6 Improving the Effectiveness of U.S. Climate Modeling -- 7 A Vision for the Future -- References -- Appendix A Steering Committee and Staff Biographies -- Appendix B Capacity of U.S. Climate Modeling to Support Climate Change Assessment Activities -- Appendix C Questionnaire Sent to Large and Intermediate Modeling Centers -- Appendix D Questionnaire Sent to Small Modeling Centers -- Appendix E Climate Modeling Survey: Summary Responses 42 Responses Received -- Appendix F Workshop Agenda -- Appendix G Workshop Participants -- Appendix H Summary of Other Relevant Reports -- Appendix I Description of Different Codes -- Appendix J Acronyms.