A patch of the Southern Ocean, south of Tasmania, has been “fertilised”
successfully with iron sulphate, causing a bloom of plankton. Because plankton
absorbs carbon dioxide, similar exercises could provide a way of helping to slow
global warming.
The latest experiment follows a similar one in the tropical Pacific
(This Week, 12 October 1996, p 4).
In that experiment, the CO2 swiftly
returned to the atmosphere. But the effect lasted longer in the Southern Ocean.
“We saw a slow but long response in plankton growth,” says Andrew Watson of the
University of East Anglia. This could allow the plankton-rich surface water to
descend to the ocean depths, locking up the CO2.
