1. Introduction -- 2. Recent and Future Change in the Meteorology of the Pacific Arctic -- 3. Recent Variability in Sea Ice Cover, Age and Thickness in the Pacific Arctic Region -- 4. Abrupt Climate Changes and Emerging Ice-Ocean Processes in the Pacific Region and the Bering Sea -- 5. The large scale ocean circulation and physical processes controlling Pacific-Arctic interaction -- 6. Physical oceanography, hydrography and shelf-basin exchange processes -- 7. On the Flow Through Bering Strait: A Synthesis of Model Results and Observations -- 8. Carbon Fluxes Across Boundaries in the Pacific Sector of the Arctic Ocean in a Changing Environment -- 9. Carbon Biogeochemistry of the Western Arctic: Primary Production, Carbon Export and the Controls on Ocean Acidification -- 10. Biodiversity & Biogeography of Lower Trophic Systems in the Pacific Sector -- 11. Marine Fishes, Birds and Mammals as Sentinels of Ecosystem Variability and Reorganization in the Pacific Arctic Region -- 12. Progress and Challenges In Biogeochemical Modeling Of The Pacific Arctic Region. The Pacific Arctic region is experiencing rapid sea ice retreat, seawater warming, ocean acidification and biological response. Physical and biogeochemical modeling indicates the potential for step-function changes to the overall marine ecosystem. This synthesis book was coordinated within the Pacific Arctic Group, a network of international partners working in the Pacific Arctic. Chapter topics range from atmospheric and physical sciences to chemical processing and biological response to changing environmental conditions. Physical and biogeochemical modeling results highlight the need for data collection and interdisciplinary modeling activities to track and forecast the changing ecosystem of the Pacific Arctic with climate change.