Air-Sea Interactions: The ocean, which stores the bulk of the sun's energy absorbed by the planet, communicates with the atmosphere via exchanges across the ocean surface. These air-sea fluxes need to be quantified in order to identify changes in forcing functions driving ocean and atmospheric circulation, which in turn control the redistribution of heat, thereby influencing global and regional climate. Evaporation of water from the ocean is an essential component of the global water cycle, which is also influenced by climate change.
Sea Level: Sea level rise, caused by warming and expansion of ocean water and by melting and runoff of land-based ice, is both an impact and a diagnostic of the Earth's energy imbalance caused by greenhouse warming. Rising sea levels have profound, regionally varying impacts on coastal communities and ecosystems. Quantification of sea level rise provides a sensitive measure of how much heat is sequestered in the ocean as a consequence of greenhouse warming.
Ocean Carbon: Ocean uptake of carbon dioxide (CO2) results in sequestration of about a quarter of all anthropogenic CO2 emissions. As such, the ocean constitutes a large sink for the greenhouse gas most responsible for global climate change. In addition, uptake of CO2 results in acidification of the ocean, with potentially significant impacts on marine biota. Observations are necessary, also, to better understand how cycling among carbon reservoirs varies on seasonal-to-decadal time scales.