Until a year ago, goings-on at the giant greenhouse known as Biosphere 2, which lies just north of Tucson, Ariz., were quasiscientific at best. The project was conceived to explore how humans might colonize space, but its dubious rationale had gradually collapsed in a series of disclosures about some highly unscientific maneuvers. Although the crews of "biospherians" who lived inside for up to two years at a time were supposed to be sealed in, oxygen and supplies were quietly imported, and carbon dioxide was removed from the atmosphere to keep it breathable. An early panel of scientific advisers resigned en mass.
The cultish fantasy shattered completely in April 1994, when the enterprise's backer, Texas oil heir Edward P. Bass, called in marshals to eject the former managers who had inspired the project and put his $200-million structure in the hands of scientists. Now under the control of a consortium led jointly with Columbia University's Lamont-Doherty Earth Observatory, Biosphere 2 is fitfully searching for a scientific identity.
The possible value of the 3.2-acre structure, which was built in 1988, resides in the fact that although it consumes prodigious amounts of energy (and money), it loses only about 10 percent of its atmosphere each year. Scientists believe that rate could permit valuable studies of sustainable agriculture and community ecology as well as of how trace elements and gases move between plants and the environment. "The engineering is remarkable by any standards," states Bruno D. V. Marino, scientific director since last September.
Certainly no other enclosed ecosystem is as large, and none can boast Biosphere 2's seven different "biomes," which include a contrived rain forest and a tiny ocean with a chemistry unlike any body of water on the earth. The new management is installing equipment that promises to make the facility perhaps the most intensively monitored patch of vegetation in the world.
That there is some scientific potential seems to be widely agreed. Already one staff researcher has obtained data suggesting a novel and possibly important effect of plants on soil microbes. Yet it is far from clear that Biosphere 2 will be able to perform research of high enough quality to attract outside funding.
Before the 1994 coup, tourists who ogled biospherians going about their tasks contributed about a third of the $6-million annual budget. Acting chief executive Stephen K. Bannon, however, sees tourism on that scale as incompatible with research. For the present, Bass is footing the bill, but Bannon says Bass "wants to see that his money is being well spent within two years." To cover all possibilities, Marino is now making pitches to the National Science Foundation.
Yet despite the can-do bravado, there are serious obstacles. For all its high-tech, the Biosphere suffers a huge disadvantage: it has no provision for doing multiple duplicate experiments, known as controls. "Replicates are essential for any statistical treatment and for scientific rigor," comments T. Hefin Jones, who studies plant ecology at Imperial College in England. W. Michael Schlesinger of Duke University, who researches the effects of elevated carbon dioxide levels on plant growth--using controls--concurs. "I don't see how they are ever going to get around that," he says.
The preliminary results obtained by staff scientist Guanghui Lin illustrate the problem. Carbon dioxide levels have fallen dramatically as a result of a mammoth ventilation exercise aimed at replenishing the facility's atmosphere. The subsequent slowdown in the growth rates of some plants seems to have prompted a similar reduction in the production of carbon dioxide by soil microorganisms. The implication of this unconfirmed observation is that in a rising carbon dioxide world, planting trees to sequester the gas might not help much--it could stimulate microorganisms to produce more carbon dioxide, thereby offsetting the amount the trees absorb.
But before the result can be published in a scientific journal, it needs to be repeated. Without separate chambers, the only way to do so is to repeat the change of atmosphere in the entire Biosphere, a monumental undertaking that could impede other experiments. And, in any event, the findings are tainted by the fact that the facility is unlike the real world: its glass restricts light from the sun by 50 percent, and there is nothing remotely like a normal insect population. Carbon dioxide levels swing each day by far more than they do in nature.
Jane Lubchenco, a former president of the Ecological Society of America, comments that ecologists have to be willing to study such unique situations. Peter M. Vitousek of Stanford University, a member of the Biosphere consortium, notes that although the project is highly artificial, it is a much easier locale for research than, say, the Amazon basin: by adding isotopes of chemical elements, investigators may examine in detail processes impossible to measure in the field.
Even if supporters are correct, it will be an uphill battle. Biosphere 2 was "in terrible shape" last year, Bannon says. Levels of nitrous oxide were high enough to prompt health concerns, and water contaminated with nitrates was raining on the vegetation. Cockroaches and ants flourished, while more desirable species perished.
For now, the consortium has decided just to clean house and try to understand the processes going on inside. Giant fans borrowed from a local mining company are forcing warm Arizona desert air through the ersatz Eden, bringing carbon dioxide levels close to normal. Some 200,000 gallons of water have been replaced, as have 12 tons of soil. Attempts are under way to study how the atmosphere has changed over time, a major challenge because some gases were absorbed into the structure's concrete. And the wildly proliferating vegetation is being catalogued.
What will come after the clean-up is still up for grabs. Marino envisages a Biosphere that will be sealed for up to three years while specific experiments are performed. The nature of those tests may depend on the funding agencies. Marino is decided on one point, however. He says he has no plans to seal humans inside again in the foreseeable future. Tourists and survivalists will be disappointed, but the rest of the world might gain insights that could start to justify Bass's millions.--Tim Beardsley
SCIENTIFIC AMERICAN August 1995 Volume 273 Number 2 Page 24
Scientific American (ISSN 0036-8733), published monthly by Scientific American, Inc., 415 Madison Avenue, New York, N.Y. 10017-1111. Copyright 1995 by Scientific American, Inc. All rights reserved. Except for one-time personal use, no part of any issue may be reproduced by any mechanical, photographic or electronic process, or in the form of a phonographic recording, nor may it be stored in a retrieval system, transmitted or otherwise copied for public or private use without written permission of the publisher. For information regarding back issues, reprints or permissions, E-mail SCAinquiry@aol.com.
