Debating Use of Iron As Curb Of Climate
By WILLIAM J. BROAD
Published: November 12, 1996
THE idea is to fertilize the sea with iron, creating such a bloom of sea plants that they gulp down tons of carbon dioxide from the atmosphere and curb the buildup of this climate-warming gas.
Long derided as foolish and politically dangerous, the idea has now been put to the test after years of foot dragging and has given strikingly good results, stirring hot debate over whether ecological tinkering might help save the planet from climatic disaster.
The test was conducted southwest of the Galapagos Islands in the Pacific Ocean, which is a fairly barren area biologically. Over a region of 28 square miles, a team of scientists slowly poured into the sea 990 pounds of iron, which is thought to be a limiting nutrient in such unproductive regions.
Almost immediately, the waters bloomed with the tiny plants known as phytoplankton, and did so over more than 200 square miles, turning the sea from blue to green.
No scientist has criticized the experiment publicly, but experts are at war over whether the test simply sheds new light on marine ecology or points to an important way to battle the effects of global warming.
Dr. Adam Heller, a chemical engineer at the University of Texas at Austin who has promoted the fertilization idea in Washington, hailed the explosive rise in ocean productivity as ''very significant, terribly significant.'' Dr. Heller said in an interview: ''We now have some way to cope with global warming should it become a problem. I wish we had more ways.''
But detractors of such global engineering say its prospect offers a false hope that threatens to encourage polluters and undercut international accords meant to curb emissions of carbon dioxide, which is released into the atmosphere by the burning of gas, oil, coal and wood and is considered a main culprit in global warming.
''As a scientific experiment, these results are fascinating,'' said Dr. Michael Oppenheimer, chief scientist at the Environmental Defense Fund, a private group in New York. ''But as a potential solution to global warming, they have limited if any value, as far as our current understanding goes.''
Fierce side debates are also developing over the cost of a program -- iron is cheap but megatons would be needed -- as well as its possible benefit of stepping up the sea's productivity and enhancing fish harvests.
Both opponents and friends of sea fertilization tend to agree that at best, its widespread use would probably cut atmospheric carbon dioxide by 6 percent to 21 percent, not enough to end the problem but potentially sufficient to dent it.
And all sides agree that the overall impact of an iron-seeding program on the ocean's ecology is riddled with uncertainties, especially for the sea's deeper ecosystems, of which little is known. In short, the cure might turn out to be worse than the disease.
Advocates of the iron-seeding idea say such uncertainties, are no reason to soft-pedal it, especially given the threat of climate change and its attendant upheavals. Years of serious research lie ahead, they say, including exploring the natural history of iron fluctuations in the sea, which some scientists now speculate may be linked to the onset of the ice ages.
''It's much too early to have a policy debate,'' said Russell Seitz, an associate of the Olin Center for Strategic Studies at Harvard University. ''Despite this, the issue seems to been born politicized. Witness the rush to criticize the hypothesis in the early 1990's before the experiment was even done. Given the extent of our ignorance, and the stakes, I'm astonished to see polemics getting the better of science.''
Part of the problem lies in the differing agendas of scientists and engineers. In general, scientists devote themselves to studying nature and unraveling its secrets, while engineers use science to rearrange nature in the service of humanity.
Periodically, the two groups have been at loggerheads, the tensions rising steadily in the last few decades as a new kind of visionary has begun to dream of global countermeasures to climatic ills, envisioning huge ecoengineering projects far beyond the engineer's usual domain of making new kinds of computers and space vehicles.
Remarkably, the current battle of the ecoengineering war centers on one of nature's smallest organisms, phytoplankton, which are ubiquitous through the sea, though their numbers vary widely, depending on local levels of nutrients.
In coastal waters rich in agricultural runoff and human sewage, their numbers can swell into the range of 100,000 per drop of water, turning the sea cloudy and brown or soupy green. Far from shore, however, phytoplankton dwindle as low as about 1 per drop, and in consequence these waters are usually deep blue.
Since phytoplankton are the most important of the sea's primary producers, trapping the abundant energy of sunlight and so becoming the foundation of the ocean's food chain, the biological productivity of each region of the sea depends on how many phytoplankton it supports.
A longstanding mystery of oceanography is that of why phytoplankton levels vary so widely, and can be low even in regions rich in nitrogen and phosphorus, the principal nutrients of plants. Seas that are low in phytoplankton but high in primary nutrients account for about 20 percent of the ocean surface.