- Joint Program Reprint
- Journal Article
Almost half of the photosynthesis on Earth is carried out by phytoplankton in the sea. So these tiny cells play a huge part in the global carbon cycle, and in regulating climate by controlling the amount of the greenhouse gas CO2 in the atmosphere. Phytoplankton are the engine of the 'biological pump' (Fig. 1) that helps maintain a steep gradient of CO2 between the atmosphere and deep ocean. It has been suggested that we might increase the efficiency of this pump — thereby drawing more CO2 out of the atmosphere — by artificially supplying nutrients to the surface oceans. This suggestion is highly contentious. Papers by Boyd et al.1, Abraham et al.2 and Watson et al.3 (pages 695, 727 and 730 of this issue) will add fuel to the debate about the desirability of such 'geoengineering' solutions to Earth's ills. The papers describe the results of a fertilization experiment in the Southern Ocean, around Antarctica, and its scientific implications for interpreting past climate change.
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