By Thomas Guengerich
SOCORRO, N.M., July 7, 2008 – New Mexico Tech chemistry professor Oliver Wingenter and his colleagues believe that modest fertilization of the Southern Ocean with iron might help slow some of the effects of global warming.
The concept of climate engineering – or geo-engineering – has scientists, activists and politicians debating the ethics and merits of environmental manipulation.
Wingenter has conducted ship-board experiments, fertilizing two small patches of the Southern Ocean with iron to study the atmospheric effects. His first experiment was over an area of ocean that was 15 kilometer by 15 kilometers. He says small-scale fertilization may abate the loss of Antarctic ice. The general principle involves seeding the ocean with a liquid slurry of iron sulfide.
German and Indian scientists are causing a furor by carrying out a massive iron-fertilization experiment over an area of 100 kilometers by 100 kilometers in the Southern Ocean, which is the globe-circling ring of ocean just north of Antarctica. They have proposed fertilizing 100 percent of the Southern Ocean, which they say would return the oceanic ecosystem to its natural balance. They are examining how much carbon dioxide is drawn down from the atmosphere into the ocean.
Wingenter’s proposal is much different. He is firmly in the middle of the debate. Instead of creating an artificial “carbon sink,” his research shows that minimal iron fertilization will create brighter clouds, which will help keep the Antarctic atmosphere colder. He proposes fertilizing less than 2 percent of the Southern Ocean with iron – but only after thorough computer modeling analyses can be completed and a slow field ramp up is implemented.
“We’re doing it slowly, in stages,” he said. “We’re not foolish here. We need to do the modeling and small-scale studies before the environmental situation becomes desperate.”
Wingenter is currently on sabbatical from his post as professor of chemistry at New Mexico Tech, a state-sponsored research university in Socorro. He, Tech student Juston Moore and Scott Elliot of Los Alamos National Laboratory are leading the effort to model Wingenter’s hypotheses. They are using the lab’s Parallel Ocean Program on supercomputers and the New Mexico supercomputer Encanto. The lab’s program has the highest resolution of all global circulation biogeochemical ocean models, Wingenter said.
During his sabbatical, Wingenter is first modeling the oceanic biogeochemistry of iron fertilization. Once those models are complete, he plans to model the atmospheric implications.
His initial article elicited a written comment from his colleagues at the University of East Anglia in England who disputed the veracity of Wingenter’s calculations. Their disagreement is about the margin of error. Their reply and Wingenter’s rebuttal will appear in an upcoming issue of the journal Atmospheric Environment.
The science behind Wingenter’s proposal is like a domino effect. Phytoplankton consume iron, but the Southern Ocean lacks enough iron for the microorganisms to flourish. The plankton produces dimethyl sulfide (DMS), which evaporates and eventually become cloud-condensation nuclei. An elevated level of cloud-condensing nuclei in the atmosphere creates brighter-than-usual clouds, which reflect more sunlight back to space.
Wingenter hypothesizes that careful seeding could help suppress atmospheric warming around Antarctica. That will be of great concern to coastal regions, because current forecasts predict that the West Antarctic Ice Sheet could slide into the Southern Ocean within the next century, causing the global sea level to rise six meters. Wingenter's research aims to prevent this and buy time for the global scientific community and energy industries to mitigate the carbon-dioxide dilemma and to develop alternatives to fossil fuels.
New Mexico Tech vice president of research and economic development Van Romero said Wingenter’s research is important for the understanding of complex global systems.
“It’s important to do this sort of scientific work to dispel the erroneous perceptions,” Romero said. “It’s especially important on these situations of global impact to apply fundamental research and to get results based on sound scientific work.”
Iron fertilization is a hotly debated issue among oceanographers. Some scientists propose wide-scale fertilization, while others consider it the worst form of geo-engineering.
The National Institute of Oceanography in India is leading proponents of planting tons of iron in the Scotia Sea south of South America.
Indian scientists say that iron fertilization will encourage rapid growth of phytoplankton, microscopic animals that remove carbon dioxide from the atmosphere. Their goal is to fertilize the entire Southern Ocean. Experts largely suspect that India and China will launch large-scale projects in an effort to buy carbon credits as they prepare to sign the Kyoto Protocol. Very limited testing has been conducted into the Indian proposal and scientists debate the effectiveness of the testing methodology.
On the other hand, Ecuador wants to ban iron-fertilization altogether … presumably because the process might have an adverse effect on their fishing industry.
The United Nations is discussing iron fertilization and is considering a ban. Wingenter proposes limited testing; specifically he wants to fertilize less than 2 percent of the Southern Ocean.
By fertilizing a small portion of the Southern Ocean, the increased level of iron will only be noticeable for one season, Wingenter said.
“During the summer months, the warmer water stays on top,” he said, “but during the winter months, the surface cools and then the cooler water from below mixes in. By the following summer all that iron is very well diluted. Then, you fertilize with iron again next summer in a different location.”
He said fertilizing 2 percent of a large test area, perhaps 10 percent of the Southern Ocean, would cost as little as $1 million to $2 million. He summarized his research in a 2007 article published in Atmospheric Environment. In that article, Wingenter explained his preliminary proposal. Citing other oceanic and atmospheric studies, he estimates that fertilizing 2 percent of the entire Southern Ocean would result in a 2 degree C decrease in average temperature over the Southern Ocean.
“Some scientists may be afraid that this geo-engineering idea might actually work and governments may relax future energy conservation regulations,” he said. “My proposal must only be viewed as a stop-gap measure. The real cure for global warming will come only when we curtail emissions of greenhouse gases.”
– NMT –