Redfield's Rule and millennial-scale
climate change

Richard T. Barber, Ph.D.
Duke University

Tuesday, March 10, 1998
1:00 p.m.—Pacific Forum

barber.gif (18437 bytes)

Redfield's Rule (Redfield, 1958) is that the supply of phosphorus, in the form of the phosphate ion, to the world ocean regulates global productivity. Redfield's Rule is widely accepted by the community of geology. Biologists, however, do not accept this rule because they rarely see evidence to support it in contemporaneous processes. Redfield’s Rule has never been tested, nor has anyone speculated on how it could be tested experimentally.

Ice-core results of the 1980s show that atmospheric CO2 has varied at least from 200 to 280 ppm on the millennial timescale. Work in the '90s set in motion by Martin's Iron Hypothesis challenges Redfield's Rule, but not in the manner John Martin predicted. Recent observations suggest that varying continental dust (with the iron it contains) alters the inventory of global nutrients on the millennial timescale. The inventory affected is the deep-ocean pool of fixed nitrogen in the form of nitrate; the process affected is the rate of nitrogen fixation in tropical surface waters.

How these varying processes might play out on the millennial timescale will be discussed.

Next: Zooplankton living in low-oxygen water

Last updated: December 19, 2000