An ambitious new study describes the full chain of events by which ocean biogeochemical changes triggered by humanmade greenhouse gas emissions may cascade through marine habitats and organisms, penetrating to the deep ocean and eventually influencing humans. Factoring in predictable synergistic changes such as the depletion of dissolved oxygen in seawater and a decline in productivity of ocean ecosystems, no corner of the world ocean will be untouched by climate change by 2100....