Human activities are influencing the ocean conditions and functions at a level that gives serious threats to our life-supporting system: ocean warming, changes in salt and freshwater distributions and in ocean circulation, ocean acidification due to uptake of part of our released carbon dioxide, nutrient inputs from land leading to eutrophication and many dead zones, changes and decline in fish stocks, migration patterns and food availability, overfishing, loss in biodiversity and many uncertainties. Coupled to these changes we are feeling climate change and variability, influencing weather patterns and seasonal conditions. Slow climate variability phenomena like El/Nino, Indian Ocean Monsoon, and North Atlantic Oscillation are probably also influenced. An increased occurrence of extreme weather events seem confirmed. In the Arctic the warming has led to almost ice free summers with related implications for warming of the surface waters, and effects on the circulation, the biological productivity and the whole ecosystem. The deep water formation in the North Atlantic and the Southern Ocean at Antarctica will probably change due to the warming and altered global freshwater and salt balances. The increased freshwater runoff into the Arctic Basin and the Greenland and Norwegian Seas leads to decreased density of the surface layer water. A weakening of the deep water formation in the region can be expected. The deep water formation in the North Atlantic is a major driver of the global deep water circulation. This can thus change due to possible weakening of the deep water formation. However, our knowledge about the deep water circulation is insufficient to forecast the development. The ocean governance has a large task to ensure that we obtain a satisfactory knowledge of the ocean deep water circulation. The lack of this is the weak link in our understanding of the climate and ocean systems. The pollution of the coastal area, the shelf seas and the open ocean is a growing problem. In the open ocean large amounts of leftovers from operations, discarded gear, much of it plastic material, have been confirmed floating around as large subsurface clouds. The pollution of regional seas by debris and garbage is substantial. The use of plastic material since the 1960s and its long decay time implies that such material is found practically everywhere also in the ocean. In the marine environment the gradual breakdown of the plastic material results in micro-size particles which attract persistent organic material as pesticides. The particles are taken in by fish and the harmful material can in this way return to humans. Scientific research and technological developments are needed also in context of the increasing importance of the contributions from the ocean to the socio-economy, the ocean being the last frontier for exploration and exploitation. Past experiences bring out the need to ensure that further development of the ocean contributions be pursued in a sustainable way. The potential of the ocean and its resources to help address our problems is vast but finite. The open ocean resources are not owned but subject to open access and outside of normal marketing. Markets fail to develop and manage them sustainably. The role of the ocean in support of trade and economic growth is very large and increasing. This underlines the need to find an economic order for non-ownership, possibly based on a stewardship or trusteeship model. The Common Heritage Principles of the Law of the Sea meet requirements for sustainable development, equity, inclusiveness and sufficiency.