What's new at Columbia's western campus? Biosphere 2 leaders discuss the progress made since Columbia transformed this unique facility into a center for visionary environmental science
Depending on whom you ask, the buildup of carbon dioxide (CO2) in the Earth's atmosphere is either the greatest threat our planet's climate may ever face or a pseudoproblem whose only possible negative consequence is avoidable economic disruption. The answer probably lies in scientific research--but how can science examine phenomena as complex as an entire planet? For practically every plausible causal linkage between human industrial activity and climate change, an alternative explanation has been offered; with only one Earth to observe, controlled study--science's most powerful tool for sorting out the plausible causes of an event--has been impossible to date.
If investigating climate change is methodologically tricky, it's just as troublesome to persuade people to do anything about it. Most earth scientists recognize that humanity's effects on the global ecosystem are an urgent problem, but it's an entirely different matter for the public and policy-makers to grasp this idea on a gut level. They can't see, smell, or taste CO2. They may read in the newspapers that temperatures are increasing--by perhaps a Fahrenheit degree. Citizens here in Arizona are likely to roll their eyes and say "Well, it's 115° in August. You're telling me it's going to be 116°. Who cares?"
A unique institution now allows for progress on both these fronts. At Biosphere 2 Center in Oracle, Ariz.--Columbia's multipurpose facility combining environmental research, education, and public education--scientists can make observations in unprecedented detail, students can participate in cutting-edge environmental research, and visitors can see the immediate effects of how factors like CO2 levels affect a more complex system. The visual observation of how cottonwood trees grow under high CO2 conditions, for example, is worth at least a thousand words. So is the observation of a bleached-out coral reef or a shrinking fish population. Since Columbia assumed management of Biosphere 2 in January 1996, its researchers have gained a foothold on problems that once seemed insoluble, identified certain crucial research areas where Biosphere 2's capabilities can best be put to use, begun developing a body of peer-reviewed scientific publications based on work that could be performed nowhere else on the planet, and instituted an innovative curriculum for undergraduates from a wide range of universities and colleges who are taking an "Earth Semester" on the campus. A new vision is now in place at Biosphere 2: the research station as a communication nexus, where the various communities with an interest in environmental change--environmental scientists, students, policy-makers, the business sector, and the public at large--can learn from each other.
One concept unites Biosphere 2's diverse activities: the observation that human activity has been fundamentally changing the nature of the Earth as a system over the last several decades, and that these systemic changes are accelerating. Increases in CO2, changes in methods of managing land and aquatic resources, changes in the nitrogen cycle, and upward trends in global temperatures all remind us that when we start to think on a planetary scale about these changes, we need to understand, first, how the Earth works without human impact and then how this human impact modifies the natural variability of the Earth. Over the next century, how we understand the difference between the two carries enormous implications for both human livelihood and environmental integrity.
The terrestrial research ship
Columbia's management of Biosphere 2 as a research station, in some ways, represents an extension of methods that Columbia ecologists have long practiced in other fields. Earth scientists from Lamont-Doherty have done a great deal of work on oceangoing vessels; the enormous greenhouse known as Biosphere 2 is the land-based equivalent of a research ship, an advanced field station with analytic facilities that allow the scientific staff to comprehend the detailed features of an entire region. Terrestrial ecologists recognize the amazing diversity of the American Southwest, going from subalpine forests at the top of the Catalina Mountains--terrain with structural and functional similarities to something one would find in Canada--through the deserts of Mexico to the Sea of Cortez. These several hundred miles of varied terrain present extreme ecologic diversity, and Biosphere 2 replicates that diversity by including six different environments (tropical rain forest, savanna, thornscrub, marsh, desert, and ocean) in its different segments or biomes. Studying each biome as a separate system (each can be cordoned off with removable plastic curtains) or studying the Biosphere enclosure as a whole, researchers can conduct controlled experiments on a full- ecosystem level, placing each individual measurement--atmospheric water, CO2, plant growth, or any other variable--in its natural context.
To date, a crucial difference between the environmental sciences and other physical sciences is the difficulty of performing controlled experiments in the former field. When all variables can be eliminated except for one or two of interest to the researcher, as in a blinded clinical trial or a laboratory manipulation, it's much easier to generate testable conclusions. In an ecosystem, however, the interplay of staggering numbers of variables (not only temperature, moisture, air pressure, solar irradiation, weather, and assorted chemical concentrations at different sites within the system, but the nearly infinite and constantly fluctuating effects of every living organism present, contributing to the system's complexity through every detail of its genetic makeup and its behavior) makes isolation of any one factor a practical impossibility. The more an experiment reduces complexity, the harder it is to extrapolate from the artifice of laboratory results to the reality of the living Earth. There is obviously no alternative Earth or "placebo Earth" to use as a control.
Biosphere 2, however, represents mankind's most ambitious attempt to construct a model of one. Vaster in scale than any greenhouse, walled off from the confounding effects of the full Earth ecosystem yet complex enough to contain a fully operating system of its own, and outfitted for unprecedentedly precise and detailed measurements of relevant variables, Biosphere 2 allows earth scientists to do what could never be done before: test their hypotheses with a reasonable degree of quantifiable certainty and experimental replicability. Indeed, events whose complexity in the real world approaches the chaotic level, such as storms, can be generated inside Biosphere 2 artificially. An investigator can induce a rain shower by manipulating the computers in Biosphere 2's command center. CO2 is isotopically labeled, allowing for precise measurement of how excess carbon affects plant growth. Since the enclosure is equipped with myriad sensors and powerful information- processing capabilities, the Biosphere 2 researchers are able to compile and organize data on an unprecedented level and derive testable hypotheses about how natural systems work.
Is coral the canary in the climatic coalmine?
Environmental scientists and activists alike have long been fond of the metaphor of the canary in a coal mine. As miners once observed caged birds, which would die from hypo-oxygenation before oxygen levels became low enough to harm humans as well, today's ecologic researchers keep an eye on certain fragile species whose declining numbers might portend trouble on the ecosystemic level. Frogs and other amphibians, which have recently experienced population declines and strange mutation frequencies in a wide range of areas worldwide, may perform this function for inland ecosystems; coral, some marine ecologists believe, may do the same for oceanic systems. A vast majority of the life in the ocean is centered around coral reefs, which shelter small fish from predators and harbor rich concentrations of algae.
However, one must exercise caution in identifying "canary equivalents." There was no mystery about what killed canaries in mines (low oxygen), but the die-backs or mutation rates that have been found in amphibians and other species remain incompletely explained. Though the coalmine-canary metaphor is rhetorically and conceptually powerful, without scientific substantiation it remains merely metaphor. Biosphere 2's ocean biome is the world's only coral reef research model in which variables such as CO2 and temperature are subject to deliberate manipulation; researchers there are now putting scientific teeth in the metaphor by conducting process-based experiments. Their early results suggest answers to long-debated questions: for example, about past and future catastrophic changes in coral and in climate.
Temperature has long been considered the dominant variable affecting the rate of calcification or growth of a coral reef system. Theorizing about the chemistry of the calcification process, however, Biosphere 2 collaborators such as Marlin Atkinson of the University of Hawaii and Chris Langdon, Taro Takahashi, and Wallace Broecker of Lamont-Doherty Earth Observatory hypothesized that rising atmospheric CO2 levels, which increase the partial pressure of CO2 dissolved in sea water, might also exert important effects by changing the equilibrium of calcium carbonate and bicarbonate ions, making calcium carbonate less available to the living coral organisms. In a terrestrial system, more atmospheric CO2 makes plants grow faster, but as CO2 dissolves in ocean water it actually slows coral growth. Subsequent experiments at Biosphere 2, changing the CO2 content of ocean water while keeping alkalinity stable, bore out this hypothesis.
It is now possible to envision a dangerous synergy between changes in CO2 and in global mean temperatures, which have risen about 1° Celsius (1.8° Fahrenheit) during the 20th century. Higher temperatures drive a thermal expansion of sea-water volume, regardless of whether glacial melting takes place as predicted. With the sea level known to be rising, reducing the amount of available sunlight reaching shallow coral reefs, and coral growth already impaired chemically by rising CO2, so little of the necessary light may reach the coral that massive die-backs could occur. The consequences of such a change would be catastrophic for the marine ecosystem and the human economy alike, affecting everything from fish populations (in the wild and in fisheries) to the oceanside tourism industry, which depends in large degree on the presence of aesthetically pleasing coral reefs. Bleaching of existing coral--reflecting loss of phytoplankton and incapacity for further growth--has already been observed in nature. The destructive process is under way now and is susceptible to an alarming acceleration in the future.
The Biosphere 2/Columbia partnership, however, enables another, more beneficial type of synergy, a practical intellectual hybridization between related research specialties. Lamont-Doherty's tradition of oceanography and paleo-environmental studies has made it possible for Biosphere 2 scientists to examine the CO2/coral hypothesis historically: If a high-CO2 future is likely to pose a hazard to coral, past periods in which CO2 is known to have been high (e.g., the Carboniferous period about 65 million years ago, when dinosaurs ruled the land ecosystem) should logically have been times of large-scale coral die-backs as well. Examination of fossil records confirmed that this was the case--and from the paleologic perspective, the CO2 hypothesis provided the missing piece in the previously unexplained Carboniferous-era die-backs. The ability to test this idea through conscious experimental CO2 manipulation puts a firm, credible, non-conjectural foundation beneath the statements scientists can now make about the urgency of cutting back atmospheric CO2 levels.
Further important discoveries are in the offing. Today's global atmospheric CO2 concentration is around 360 parts per million (ppm), and studies of the effect of higher CO2 on plant growth most commonly involve roughly twice that level, about 700 ppm--but there is no reason to suppose that the changes wrought by industrial society will somehow magically stop at double the current level. (Some experts estimate that the Earth's CO2 will approximately triple by the year 2100 if "business as usual," in terms of anthropogenic environmental damage, continues.) Up to a point, plants respond to increasing CO2 with roughly linear increases in photosynthesis and growth, incrementally absorbing the additional CO2, but can this process continue indefinitely? Biosphere 2 can generate extremely high CO2 conditions for study in one or more biomes, and resident ecophysiologist Guanghui Lin has demonstrated that a CO2 satiation threshold exists in a rain-forest system: Beyond about twice today's CO2 concentration, feedback mechanisms slow down and level out the photosynthetic process, rendering the flora incapable of further absorption.1,2 The linear dose-absorption relation that normally describes the behavior of an isolated plant does not hold at the full ecosystem level. The implications for theories that Earth's self-regulating mechanisms can respond to any rise in CO2 appear obvious: It would be unwise to assume that the planet will always maintain equilibrium no matter what humans do to its atmosphere.
Frank Press, former president of the National Academy of Sciences, has described Biosphere 2's work on ocean/atmosphere interactions as the first unequivocal experimental confirmation of the human impact on the planet. Strengthening the scientific underpinnings of any Kyoto-style projections about climate change is obviously essential--but it is only half the battle. Since the general public rarely receives sophisticated interpretations of either the science or the politics surrounding environmental questions (with the media customarily framing such questions in terms of false dichotomies between jobs and a healthy environment), a sound scientific consensus is necessary, but not sufficient, to catalyze real changes in policy and behavior. For this reason, we have come to define our mission at Biosphere 2 as a fusion of high-level science and open scientific communication to the public. Every visitor to the facility brings back not only a firsthand experience of practical scientific work, but a greater awareness that protecting and restoring Earth's balance doesn't have to mean shutting down human society--just making more intelligent and informed choices about humanity's role in the complex systems that sustain life.
1. Lin G, Marino BDV, Wei Y, Adams J, Tubiello F, Berry JA. An experimental and modeling study of responses in ecosystems carbon exchanges to increasing CO2 concentrations using a tropical rainforest mesocosm. Aust J Plant Physiol 25:547-556.
2. Lin G, Adams J, Farnsworth B, Wei Y, Marino BDV, Berry JA. Ecosystem carbon exchange in two terrestrial ecosystem mesocosms under changing atmospheric CO2 concentrations. Oecologia, in press.
William C. Harris, "Biosphere 2 Center Update," Columbia Earth Institute's EARTHmatters, Winter 1998-99
Intergovernmental Panel on Climate Change, United Nations Environment Programme
U. S. Global Change Research Information Office
Center for International Earth Science Information Network (CIESIN), Columbia-based non-governmental organization
Center for the Study of Carbon Dioxide and Global Change
Press release on Columbia/Princeton/NOAA studies on CO2 absorption, Oct. 15, 1998
Ecologists' statement on the consequences of rapid climate change, group letter to Pres. Clinton, May 20, 1997
EcoNet Climate Resources Directory, Institute for Global Communications
Global Warming Special Report, Environmental News Network
Carbon Dioxide Information Analysis Center, U.S. Department of Energy
White House Initiative on Global Climate Change
Global warming page, Cooler Heads Coalition, market-oriented advocacy group
Bruce Sterling, "The Manifesto of January 3, 2000" (on impending ecological damage as a technocultural issue)
WILLIAM C. HARRIS, Ph.D., is executive director and president of Biosphere 2 Center. LISA J. GRAUMLICH, Ph.D., professor of geography and regional development at the University of Arizona, served as director of the Earth Learning Center and deputy director of Biosphere 2 Center during 1998.
Photo Credits: Illo: Howard R. Roberts
Photos: Gonzalo Arcila