Part I. Introduction: 1. Introduction to climate modeling; 2. Human components of the climate system; Part II. The Science: Subsystems and Processes: 3. The atmosphere; 4. The ocean circulation; 5. Land surface; 6. Terrestrial ecosystems; 7. Atmospheric chemistry; 8. Marine biogeochemistry; Part III. Modeling and Parameterization: 9. Climate system simulation: basic numerical and computational concepts; 10. Atmospheric general circulation modeling; 11. Ocean general circulation modeling; 12. Sea ice models; 13. Land, ice and climate; 14. Biophysical models of land surface processes; 15. Chemistry transport methods; 16. Biogeochemical ocean models; Part IV. Couplings and Interactions: 17. Global coupled models: atmosphere, ocean, sea ice; 18. Tropical Pacific ENSO models: ENSO as a mode of the coupled system; Part V. Sensitivity Experiments and Applications: 19. Climate variability simulated in GCMs; 20. Climate-model responses to increased CO2 and other greenhouse gases; 21. Modeling large climatic changes of the past; 22. Changes in land use; Part VI. Future Prospects: 23. Climate system modeling prospects.