2009年以降、我々は「Continental–Oceanic Mutual Interaction」シリーズとして、陸域と海洋の相互作用を通じた地球規模の物質循環を議論してきた。これまで、ENSOや熱帯大西洋の海面水温変動が流域の水循環に及ぼす影響を示してきたが、2022年以降は「Core Biome Complex」概念を導入し、生態系を他惑星環境へ拡張する試みを進めている。本セッションでは、その延長として「惑星海洋系」を新たな視点で捉え、(1)火星における古海洋が気候に与えた影響、(2)将来的なテラフォーミングにおける人工海洋の可能性と規模を議論する。また、(3)海洋惑星と乾燥惑星の比較を通じ、海洋の存在が惑星の気候安定性と居住可能性に果たす役割を探る。地球科学・惑星科学・気候モデル・生命圏科学・テラフォーミングなど、分野横断的な議論を歓迎する。

Since 2009, we have organized a series of scientific sessions entitled"Continental-Oceanic Mutual Interaction: Global-scale Material Circulation through River Runoff" at the Japan Geoscience Union (JpGU) Annual Meeting. The series has explored the dynamic exchange of heat and materials between land and ocean systems, highlighting global-scale interactions such as the correlation between Amazon River discharge and SST anomalies associated with ENSO and the Tropical Atlantic. These studies emphasize the river-ocean continuum as a key regulator of planetary climate stability. In recent years, we have extended this framework through the concept of the Core Biome Complex, which envisions terrestrial ecosystems as adaptable units that could function within extraterrestrial environments. Building on this foundation, the 2026 session expands the discussion beyond Earth to investigate planetary-scale ocean systems and their implications for planetary climate and habitability. The session will focus on: (1) Evaluating the climatic influence of ancient oceans on Mars and their possible role in sustaining transient habitable conditions; (2) Assessing the feasibility and scale of artificial oceans in future terraforming scenarios, from atmospheric engineering to hydrological cycling; and (3) Comparing ocean planets and non-oceanic (dry) planets to clarify how the presence or absence of global oceans affects long-term climate stability and biospheric potential. Through these discussions, we aim to connect Earth-based understanding of river-ocean interactions and material cycles to planetary climate evolution and the design of future habitable environments. We welcome contributions from Earth scientists, planetary scientists, climate modelers, astrobiologists, and others exploring the frontier between natural planetary processes and engineered habitability.