Even though water covers over 70% of the globe, most people don't think about how climate change might impact the ocean. Those of us who live on land tend to notice changes in the atmosphere such as air temperature, precipitation, storm activity, cloudiness, air pollution, carbon dioxide levels, etc. The ocean also interacts with the atmosphere and thus is changing with climate, as well; noticeable changes include ocean currents, ocean temperature, and shifts in marine biological patterns (e.g., phytoplankton, zooplankton, fish abundance and species diversity). Drastic changes in climate can lead to dramatic consequences incluing sea level rise and ocean acidification.

The vast and remote nature of the ocean makes it difficult to observe climate change impacts. While the global ocean surface can be monitored by satellites, sub-surface ocean data is sparse. These sub-surface data are available mostly from buoys and occasional ship surveys. Likewise, paleoclimate data from the oceans are limited to sediment cores. Thus the development of reliable "diagnostic" computer models is key to understanding how and why the ocean has changed in the past. Such diagnostic models can also help to create "prognostic" models, with the goal of predicting how the oceans might respond to future climate change scenarios.