“The identification of a key factor controlling phytoplankton growth and thus contributing to climate change over the last several glacial/interglacial cycles was initially controversial, but is now widely accepted.”

The more highly cited works lie at the intersection of several fields, including geochemistry, phytoplankton physiology, oceanography, carbon cycling, and climate. The identification of a key factor controlling phytoplankton growth and thus contributing to climate change over the last several glacial/interglacial cycles was initially controversial, but is now widely accepted. In addition, there are profound implications regarding the application of these findings to control climate.

  What are the circumstances which led you to your work?

I had been studying oceanic trace metal distributions and metal speciation for several years. A natural extension of my studies was to determine the effects of metal speciation and concentrations on phytoplankton production. My Ph.D. research paralleled that of Dr. John Martin and we each tested the same hypothesis on the same cruise to the SubArctic Pacific. From these initial experiments and similar findings, I worked with Dr. Martin and when he passed away, Dr. Johnson and I took over leadership of his research group.  The first open-ocean iron enrichment experiments were performed following John's death, yet we all agreed to list him as first author of the paper that resulted.  The significance of these findings and the experiments that followed led to a fundamental transformation in the way we think about ocean ecosystems and carbon cycling.

  How would you describe the significance of this work for your field?

The impact of this work has been profound, not necessarily for the accomplishments of our group, but for the way it has changed the thinking of others in ours and related fields.

  How much has this research advanced since you first started publishing on it?

Originally ours was an idea that was considered preposterous, simplistic, and radical and was ridiculed by many in ocean science.  It has evolved as many new ideas do: to an idea now embraced by many.  Success has many fathers. Surprisingly, the analytical methods for the determination of iron in seawater have not advanced very quickly, yet many nations have since repeated our original experiments with similar results.  In short, the iron hypothesis has advanced to a theory.

  Where do you see this research going 10 years from now?

The increase in atmospheric carbon dioxide, the associated impacts on climate, and a growing international awareness and responsibility to deal with it will compel more applied studies of iron-induced phytoplankton growth in the oceans.  This will require the investigation of all major biogeochemical provinces, including coastal and oligotrophic systems.  It is my hope that these studies will be science-based and not solely motivated from a geoengineering perspective.

Kenneth H. Coale
Moss Landing Marine Laboratories
Moss Landing, CA, USA