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The idea of encouraging the growth of sea life as a way of soaking up carbon
dioxide has resurfaced in a patent by Michael Markels of Springfield, Virginia.
A ship moves in a spiral pattern over deep water, dispersing fertiliser to
create a bloom of phytoplankton. The plankton sink to the bottom of the ocean
when they die, taking with them the carbon they absorbed at the surface (WO
00/65902). Markels experimented by adding iron salts to an area of the tropical
Pacific. The phytoplankton volume increased by a factor of 27 over nine days,
yielding 272 kilograms of plankton per kilogram of fertiliser. He estimates the
cost at $5 per tonne of carbon stashed away.