Global-mean surface temperature has risen by more than 1oC in response to anthropogenic increase of atmospheric greenhouse gases. How does the ocean circulation change, by what mechanisms, and how does it affect the atmospheric circulation and regional climate change? This lecture explores these questions brought to the fore by climate change.

Oceanographers led the way in developing coupled ocean-atmosphere theory of El Nino and the Southern Oscillation, culminating in operational climate forecast at seasonal leads. Ongoing global warming opens new frontiers for dynamic oceanography to uncover physical mechanisms and predictability for climate and marine biogeochemical cycles.