Ocean observation research theme under ArCS project, “Theme 4: Observational research on Arctic Ocean environmental changes”, aimed to elucidate the status and trends of ongoing Arctic Ocean environmental changes and to evaluate their impacts on Arctic marine ecosystem and the global climate system. For these purposes, we conducted field observations, mooring observations, laboratory experiments, numerical modeling, and international collaborative research focusing on the Pacific Arctic Region (PAR) and from Pan-Arctic point of views. As a result, we have published several scientific studies on environmental changes and their impact on the climate and ecosystem. In this manuscript, we compiled these results with some concluding remarks. We found physical environmental changes of water cycle, sea-ice and ocean conditions, heat transport, and ocean mixing in the Arctic Ocean and surrounding areas. We also examined chemical properties, carbon, cycle, and ocean acidification in the Arctic Ocean. In addition, new findings regarding impacts of sea-ice reduction to primary productivities were published. For public outreach of Arctic research, we were able to develop an educational tool (a board game named “The Arctic”) in collaboration with Themes 6 and 7.

ArCS项目下的海洋观测研究主题为“主题4：北冰洋环境变化的观测研究”，旨在阐明北冰洋正在进行的环境变化的现状和趋势，并评估其对北极海洋生态系统和全球气候系统的影响。为此，我们针对太平洋北极地区（PAR）并从泛北极的角度进行了现场观察，系泊观察，实验室实验，数值模拟以及国际合作研究。结果，我们发表了一些有关环境变化及其对气候和生态系统影响的科学研究。在本手稿中，我们总结了这些结果。我们发现水循环，海冰和海洋条件，热传输，和北冰洋及周边地区的海洋混合。我们还检查了北冰洋的化学性质，碳，循环和海洋酸化。此外，还发布了有关减少海冰对初级生产力的影响的新发现。为了使北极研究更广泛地与公众接触，我们能够与主题6和主题7合作开发一种教育工具（名为“北极”的棋盘游戏）。