The hypothesis of these experiments is that fertilizing the oceans with iron could sufficiently boost photosynthetic rates of floating patches of microscopic plants called phytoplankton to remove large amounts of carbon dioxide from Earth's atmosphere, said Richard Barber, a professor of biological oceanography at Duke's Nicholas School of the Environment and Earth Sciences.
According to the hypothesis, extra carbon dioxide absorbed during photosynthesis would be converted into plant tissue that would then sink deep into the ocean, removing the gas from circulation for long periods. But, so far, "that result has not been shown," Barber said.
Barber will discuss the subject at a symposium beginning at 9 a.m. PT on Friday, February 13, 2004 during the American Association for the Advancement of Science's 2004 annual meeting in Seattle.
CO2 is among several gases believed to contribute to warming Earth's climate by trapping extra amounts of the sun's heat -- something like a greenhouse. The "iron hypothesis" method of scrubbing the atmosphere of much of its carbon dioxide was proposed in 1990 by John Martin, an oceanographer at Moss Landing Marine Laboratory in California, who died before he could test the idea.
Barber, a long time colleague of Martin's, served as chief scientist on an initial cruise, to the equatorial Pacific, to evaluate how marine life would respond to extra iron.
In that and subsequent cruises, he and other scientists have documented that phytoplankton photosynthetic rates did quickly increase in response to iron fertilization. The unanswered question is what ultimately happens to the assimilated CO2.