Ocean & Climate
The ocean is a major player in the Earth’s climate. It holds the largest reservoir of active carbon and thereby largely determines atmospheric carbon dioxide levels. Ocean circulation transports heat and salt from low to high latitudes and drives vertical mixing of carbon, nutrients and oxygen between the upper and deep ocean. The vast ocean floor has accumulated sinking material for millions of years and hence its sediments offer long records that capture Earth’s climate variability. Together, these lines of research combine to improve our understanding of the dynamic link between our ocean and climate on successive time scales as well as human interference with the ocean.
Ocean as CO2 and heat sink
Planktonic organisms take up dissolved inorganic carbon for photosynthesis (algae) and calcification (foraminifera, coccolithophores and gastropods), contributing to the eventual removal of carbon from the ocean’s surface. Heat is provided mostly at the ocean surface. To predict our future climate accurately, it is essential to understand how the ocean absorbs, transports and stores heat through dynamic processes like circulation and mixing.
Archives of environmental change
Major transitions in Earth’s climate system leave strong marks in the sedimentary record. More detail on those climate changes and the link with the ocean can be obtained by analysis of geochemical, biological, and physical parameters in these sediment archives. Palaeoceanographic reconstructions based on these parameters help to understand the climate system under anthropogenic pressure, such as the effect of CO2 on global temperatures.
Ocean circulation and climate
Ocean currents act much like a conveyer belt. They are important for the transport of heat, nutrients, and dissolved gases such as CO2. Warming of the ocean and input of freshwater from Arctic Sea-ice and melting polar icecaps are affecting the ocean circulation. Sustained observations of basin-wide transports provide insight into the changing circulation and help to validate and improve climate models.