Iron versus the Greenhouse: Oceanographers Cautiously Explore a Global Warming Therapy
Monastersky, Richard, Science News
Nothing had prepared Kenneth Coale or his shipmates for the color of the water. The oceanographers watched in awe as the R.V. Melville plied Pacific waves dyed a soupy green by a bumper crop of tiny ocean plants.
The tint was abnormal. Only a day before, this patch of water near the Galapagos Islands had sparkled with electric blue clarity, a quality owed to the general absence of microscopic plants called phytoplankton. Coale and his colleagues had transformed this marine desert into a garden simply by sprinkling a dilute solution of iron into the water.
"We had predicted the response, but none of us was really prepared for what it would look or feel like," says Coale, a researcher at the Moss Landing (Calif.) Marine Laboratories. "There were some of us who were quite pleased and others of us who would walk out on the fantail and burst into tears. It was a profoundly disturbing experience for me. We had deckhands come up to us and ask, 'Did we do this?' "
Indeed they had, and some of the scientists feared that the repercussions would ripple far beyond this small sector of water. Although designed to test basic theories about marine ecology, the Pacific experiment had demonstrated all too dramatically the effects of adding iron to the ocean--a scheme known as the Geritol solution to global warming. By spreading just half a ton of iron across 100 square kilometers of the Pacific, the oceanographers had stimulated enough plant growth to sop up some 350,000 kilograms of carbon dioxide from the seawater. If performed on a grand scale, iron fertilization of ocean water could absorb billions of tons of carbon dioxide from the air, enough to slow the rate of greenhouse warming, according to some rough estimates.
The Geritol solution, named for the venerable iron supplement, represents only one of many geoengineering quick-fixes dreamed up to stave off global environmental problems. The proposals range from low-tech to Star Trek, from planting trees to stationing a huge filtering screen between Earth and the sun. Some people promote these megaprojects as a planetary salve, easing the pain of global warming without requiring society to address the root cause, its dependence on fossil fuels. Others view them as last-ditch efforts that could save Earth should efforts to reduce pollution prove ineffective.
Coale and many others who witnessed iron's tremendous greening effect loathe the idea of tinkering with the globe in such a heavy-handed way. But he admits that the overwhelming success of the iron experiment could well generate a wave of support for geoengineering proposals.
"We have demonstrated that we have the key now for turning this system on and off," says Coale. "I think some will be encouraged by these findings. Therein lies the dilemma."
The idea of stimulating plankton growth with iron grew out of the fertile mind of the late John H. Martin, an oceanographer at Moss Landing. Martin sought originally to explain a long-standing mystery concerning barren waters in the Antarctic, subarctic, and equatorial Pacific Oceans. With the abundant concentrations of nutritious nitrate and phosphorus in all three regions, phytoplankton should thrive. But it doesn't.
Martin became convinced in the late 1980s that lack of iron deeps the phytoplankton from making use of the nutrients and that a little extra iron would trigger rapid growth of the plants. He calculated that it would be feasible to fertilize the ocean on a massive scale, eventually drawing carbon dioxide out of the atmosphere and deep-sixing the greenhouse gas into the nether reaches of the ocean. Want to slow global warming? Just add iron.
He announced this possibility somewhat facetiously in July 1988 at a lecture at the Woods Hole (Mass.) Oceanographic Institution. "Putting on my best Dr. Strangelove accent, I suggested that with half a shipload of Fe [iron] . . . I could give you an ice age," he recalled 2 years later in the newsletter of the Joint Ocean Global Flux Study. …