Our current understanding of how climate change due to increasing greenhouse gases is expected to affect oceanic biology and of how the physical-biological feedbacks may influence the evolving physical climate system is summarized. The primary effects of ocean biology on physical climate include its influence on the carbon cycle, the influence of oceanic phytoplankton on upper-ocean absorption, and the influence of DMS production by phytoplankton on atmospheric aerosols. The primary influences of physical climate on the ocean biology are the influence of aoelian dust deposition and the multitude of ways that community structure can be altered. The focus is on the tropical and midlatitude Pacific Ocean, with results from other ocean basins also noted.