Twenty years advocating for oceans science

To some people, iron fertilization was the opportunity of a lifetime: get rich and help stop climate change, all at once! But Dalhousie’s John Cullen wasn’t buying it.

For 20 years, Dr. Cullen worked to bring attention to the uncertainties and potential dangers of large-scale iron fertilization, a process whereby iron is released into the ocean to prompt phytoplankton growth. The idea was that phytoplankton would soak up carbon dioxide, a high-profile greenhouse gas. The carbon would then be stored in the deep sea, keeping it out of the atmosphere. It was hyped as a simple solution to climate change.

Dr. Cullen disagreed. In order to store significant amounts of carbon, he argued, huge sections of ocean would need to be fertilized and fundamentally changed, with uncertain and potentially catastrophic ecological impacts.

Dr. Cullen and his colleague, Sallie W. (Penny) Chisholm from MIT, recently received the Ruth Patrick Award from the American Society for Limnology and Oceanography. The award honours outstanding research by a scientist in the application of basic aquatic science principles to the identification, analysis and/or solution of important environmental problems. Previous recipients include the noted aquatic ecologist David Schindler of the University of Alberta.

In the beginning

Reflecting on his two decades of research and advocacy, Dr. Cullen remembers a long struggle to apply scientific research for protection of the ocean.

In 1988, new discoveries by oceanographer John Martin suggested that small amounts of iron from natural or artificial sources could increase production of phytoplankton in the ocean. The issue became controversial because if Dr. Martin’s “Iron Hypothesis” were true, fertilization of the ocean with iron might be used to slow global warming driven by increasing carbon dioxide in the atmosphere.

Cullen and leading ocean scientist Penny Chisholm co-chaired an international symposium in 1991, with the goal of fostering communication among scientists about iron fertilization. At the end of the meeting, participants constructed a consensus resolution concluding that the topic of iron and marine productivity was a priority for research, but governments should not think of it as a solution to offset carbon dioxide emissions.

This symposium paved the way for highly influential research, including open-ocean fertilization experiments that demonstrated significant promotion of ocean productivity by iron. Although the results of these relatively small-scale experiments could not be used to predict effects on climate with scientific confidence, commercial interest blossomed. Patents were issued and at least one business began advertising that they would fertilize the ocean and end the greenhouse effect, all the while making investors rich.

"By 2001 it was getting pretty intense," recalls Dr. Cullen. "There were a lot of businesses looking into fertilizing the ocean for profit by generating carbon credits."

Discrediting ocean fertilization

Over the next few years, commercial interest continued to increase. Dr. Cullen, along with Dr. Chisholm and Paul Falkowski of Rutgers University, began to fear for the integrity of oceans subjected to commercially driven habitat modification on a global scale. They argued in the journal Science that fertilization of the ocean for profit should never be allowed.

Over the following years, a debate developed, with some scientists in favour of commercially supported research, and others opposed. Dr. Chisholm and Dr. Cullen argued for a cautionary approach: there were risks that could not be assessed unless experiments were done on huge expanses of the sea and by the time the negative effects became known, it would be impossible to reverse the damage done.

Through the years of debate, Dr. Cullen reiterated a central message: “Unless you can dismiss these scientific arguments, we should not proceed with ocean fertilization for climate mitigation." All along, Dr. Cullen and colleagues have strongly supported basic research on iron, ocean productivity, and climate.

International oversight

Today the International Maritime Organization (IMO) and The UN Convention on Biodiversity are involved in the ocean fertilization issue. Scientists interested in ocean fertilization have collaborated and adopted guidelines for research – “A great improvement to the previous unstructured approach,” says Dr. Cullen.

“It’s quite an honour to be recognized for this,” he adds. “When you see something important to the world, you apply what you know to the problem and hope that it helps governments and international bodies to make decisions based on science. When they do that, I can’t ask for anything more.”

John Cullen will be speaking on the topic of optical observation of the ocean over the past 150 years on Tuesday, Feb. 28 at 4 p.m. in the Great Hall of the University Club.