Uptake and storage of anthropogenic carbon dioxide in the ocean is related to the reaction of dissolved carbon dioxide with water to form bicarbonate (and minor quantities of carbonic acid and carbonate). Alkalinity, the excess of bases in solution, governs the efficiency at which this occurs and provides buffering capacity towards acidification. Here I present the biogeochemical processes impacting the ocean carbonate system over multipletimescales. Over geological time scales alkalinity input to the ocean from weathering should be in balance with removal via carbonate mineral burial in the sea. However, a re -evaluation of the modern oceanicalkalinity balance revealed that the so far neglected riverine delivery of particulate inorganic carbon should be included to balance inputs and outputs. Next I present a retrodiction of ocean alkalinity, dissolved inorganic carbon and pH over the last 50 million years.

Climate change impacts and growing human activities at sea, at the coasts and in the oceans require an international system of monitoring and forecasting that supports a science-based approach tomanagement. In Europe, the Copernicus program has been developed in the past ten years to implement the backbone of operational oceanography from the global to the regional European seabasins, serving the ocean community at large, especially the academic one. Predictions and long-term reanalysis of the past state of the oceans allow to explore the oceancirculation dynamics and the connected pelagicbiochemical cycles with unprecedented accuracy and completeness. It is a new era of abundant data to explore the earth system dynamics.

The ocean is essential to our society – it regulates the global climate, provides us with natural resources such as food, materials, important substances, and energy. It is essential for international trade and recreational and cultural activities. Ocean observations touch our lives every day from the food we eat, to the clothes we wear, to how we spend our leisure time. The ocean is estimated to be the seventh largest economy in the world. Goods and services from coastal and marine environments have been estimated at US$2.5 trillion each year worldwide. Together with human development and economic growth, increased use and overuse of ocean resources and services have exerted strong pressure on the marine environment, ranging from overfishing, unsustainable resource extraction, and alteration of coastal zones to various types of thoughtless pollution including CO2 emissions causing climate change - the ocean is warming,acidifying, deoxygenating and sea level is rising.