The marine biology community is being shaken up by a controversial theory that promises to help put the brakes on global warming by reducing atmospheric greenhouse gases. Iron fertilization adds iron to the ocean to activate the biological pump process, taking CO2 out of the atmosphere and bringing it to rest in the deep ocean. The biological pump is a complex phytoplankton-based ecosystem that is driven by sunlight and fueled by the supply of inorganic nutrients from the deep ocean. Deep ocean waters are about 200% supersaturated with CO2 compared to surface waters, which are in contact with the atmosphere.