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Biosphere 2

Figure 1. Overview of the Biosphere 2 complex, showing the location of one of the two
dome-like "lungs" (top, right). Picture from the
Biosphere 2 website (Columbia University).

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Biosphere 2 - overview and short history

Biosphere 2 is a major sealed glasshouse complex near the small town of Oracle, north of Tucson in the desert of Arizona. It was completed in 1991, funded by a Texan oil billionaire, Edward P. Bass, whose vision was that it could be a step towards the colonisation of Mars by humans. With this in mind, the complex had to be large enough to support humans and to be self-sustaining, with recycling of all its components. It was designed to accommodate small teams of people who would live in it for periods of up to 2 years, obtaining all their food by growing crops or by eating domesticated animals, replenishing the oxygen by plant photosynthesis, and recycling of all their consumables. Even the toilets had no toilet tissue; instead they had an inbuilt spray for...well, you know what!

In short, the sealed complex was designed as a model, sustainable, controlled environment system - a visionary experiment on a grand scale. It contains several different compartments, supporting different types of vegetation (biomes). It is called Biosphere 2 because it aims to mimic Biosphere 1 - planet Earth.

Figure 2. A small part of the Biosphere 2 complex - the large glass structures are part of the agroforestry zone (see Figure 3)

The building itself is a major technological and architectural achievement, with many innovative features. Its total internal area covers 1.28 hectares (3.15 acres) and the different compartments house different biomes (mesocosms) - rainforest, agroforestry, savanna, desert, marsh, ocean with coral reef, and a human habitat zone with all creature comforts such as a kitchen, library, dormitories, etc. Supporting all this is an astounding array of technology, including fully automated, computer-controlled internal weather systems and recycling systems. Heating, cooling, and electricity are supplied from an energy centre external to the structure, with solar panels to supply much of the energy. Water is conserved inside the Biosphere 2 wilderness mesocosm (desert, marsh, savanna, and rainforest) and is recycled by condensation (cooling coils), artificial rain or irrigation (sprinkler systems), evapotranspiration, and sub-soil drainage.

In order to compensate for changes in air volume caused by solar heating (alternating day and night temperatures) two large dome-shaped "lungs" were constructed. These are like gasometers - the roofs rise and fall to accommodate the changes of internal air volume. The individual compartments of the glasshouse complex can be operated in different ways, including `flow-through' and `closed system' modes. The whole structure contains (for the record) approximately 170,000 metres3 of atmosphere, 1,500,000 liters of freshwater, 3,800,000 liters of saltwater, and 17,000 metres3 of soil.

Figure 3:  Locations of Biosphere 2 mesocosms/ biomes (copied from the Biosphere 2 website).

For more photographs of the Biosphere 2 complex, click here.

Biosphere 2 is located at an elevation of 1,200 metres above sea level at a latitude of 32.5o North. The surrounding area is temperate desert, so the outside temperature is usually hot and the sunlight is intense. See Figure 4.

Figure 4. The view from Biosphere 2. Notice the cacti (including prickly pear) in the foreground and the many
giant columnar cacti (saguaro) on the slope descending from left to right in the middle distance.

Stocking the biomes within Biosphere 2

Much thought - though perhaps not enough thought - went into the creation of the biomes. The soils in the complex were specially prepared from commercially supplied components and mixed to give the desired properties. Plants were imported from various locations to represent different types of vegetation (desert communities, tropical rainforest, etc.), and a selection of insects, reptiles and fish were introduced. However, no mammals or other natural grazers were introduced, for fear that they would get out of hand. Instead, the vegetation had to be controlled (pruning, cutting, etc.) by the Biosphere inhabitants - the "biospherians". But separate areas were constructed for housing chickens and pigs, which could be managed to provide food for the inhabitants.

What happened when people moved in?

An initial series of short "test module" experiments started in 1988, when researchers spent from 3 to 21 days in the Biosphere 2 complex, to test the feasibility of the project. Then in September 1991 a crew of 8 people entered the sealed complex for a 2-year period. This was the first of many trials that were expected to continue over a period of 100 years before the programme ended.

After that initial crew, a second crew of 7 people entered Biosphere 2 in March 1994. But by this stage the strategy had changed because of the problems that had been found during the first 2 years. It was decided that individual crew members would spend shorter periods inside the structure - about 180 days on a rotating basis, and scientists or other visitors would enter the complex for short periods, to conduct experiments or to sample the populations or organisms.

The initial plan for Biosphere 2 was that the crews would support themselves entirely from the food that they could grow or gather, and that the "sealed" Biosphere complex would be entirely self-supporting.

However, serious problems soon started to develop. It is difficult to give an accurate account of all the problems because the official press releases give only some of the relevant information - remarkably for such a major technological and scientific venture, there seems to have been no detailed record or log kept of the day-to-day problems. But the major problems can be summarised under four main headings: technical problems, human and social problems, management problems, biological problems.

1. Technical problems

Soon after the first crew entered Biosphere 2, the oxygen levels in the complex started to fall and eventually reached damagingly low levels - below 14.5% compared with the normal 21% [14.5% is the oxygen level found at an altitude of about 4100 metres (13,400 ft)] This low oxygen level caused fatigue (equivalent to altitude sickness) and threatened the inhabitants' wellbeing. It is said that the inhabitants lacked the energy to climb the 100 or so stairs to the library (see Figure -), so this facility soon became non-functional. In addition, the nitrous oxide and CO2 concentrations rose to high levels. In order to help manage these problems, it was decided that the giant "lungs" (which compensated for changes in air volume) would be opened to the exterior when they were fully dilated each day, so that some fresh air could be introduced into the "closed" environment. Later, it even became necessary to pump oxygen into the system. Much of the reason for this oxygen deficit seems to be that oxygen was absorbed by some of the concrete structures in Biosphere 2 - the "curing" process of new concrete - and this was subsequently overcome by sealing the concrete. However, it is likely that a contributory cause of oxygen depletion (and CO2 increase) was the high organic matter content of the original soils (see later).

Added to these problems, there was some air leakage, estimated at about 10% per annum, between the inside and the external atmosphere. It has been pointed out that this amount of leakage is almost inevitable - in fact, it is similar to the leakage from spacecraft - but it caused some critics (including a sceptical press) to claim that the whole basis of the project - a sealed environment - was invalidated by air leakage and by the need to open the lungs to the outside world.

A further technical problem was that the glass and other structural components act as filters for incoming solar radiation. Virtually all UV radiation is absorbed by the glass, and photosynthetically active radiation (PAR) is cut by about 55%. However, because of the sunny location of Biosphere 2, the mean daily PAR levels measured inside the agro-forestry zone (about 15 mol m-2 day-1 in winter and 25 mol m-2 day-1 in summer) are higher than typical greenhouse intensities.

Yet a further problem could not have been foreseen - there was that an unusually heavy El Nino current which caused this part of Arizona to have an exceptionally cloudy winter (1991-1992). This cloud cover seriously reduced the amount of photosynthesis in Biosphere 2. As a consequence, the amount of CO2 within the structure rose to substantially higher levels than normal. It had to be corrected by chemical trapping of the CO2. A contributory factor could have been the choice of soil used in some of the biomes - an artificial mixture with up to 35% organic matter. Soil microorganisms can be expected to thrive on this, degrading the organic matter and releasing large amounts of CO2.

2. Human and social problems

The biosphere inhabitants soon found that they could not generate enough food to sustain themselves. They had brought in various seeds (peanuts, maize, vegetables, etc. - even coffee) which would be sown to produce crops (and which would generate more seeds for subsequent seasons). These annual crops were grown in rotation in 18 separate plots in the agroforestry zone. They included rice, wheat, maize, sorghum, sweet potato, potatoes, beans, soybeans, rape, mustard, safflower, tomatoes, cabbage, carrots, eggplant (aubergine), peppers and leafy vegetables.

But the biospherians were not experienced agronomists, and they had many problems with insect pests and plant diseases because they had to rely on natural (biological) control practices rather than chemical pest control measures, and the biological control methods did not always work well. As their food crisis deepened, the biospherians decided to eat some of the stores of seeds they had brought in, which were intended to be used to produce more food. At quite an early stage they found that bananas were one of the easiest and most nutritious food sources that they could use (in the rainforest zone) so they allowed the bananas to proliferate naturally (from rhizomes), and bananas now dominate that zone.

The initial intention was that chickens would be used as a continuing source of eggs, but the biospherians could not afford to use the limited amounts of food to feed the chickens, so these were slaughtered and eaten. The pigs also were in competition with the food demands of the humans. So, the pigs were slaughtered and eaten.

The biospherians were perpetually hungry and lost an average 16% of their body weight in the first 6 months (then stabilised thereafter). Despite this, they remained physically healthy. In fact, one of the more lasting scientific contributions from Biosphere 2 has been the recognition that a restricted (energy-limited) diet can increase health and longevity, as long as it is a "nutrient-dense" diet, with all the essential ingredients. (See related article)

There were inevitable interpersonal difficulties, doubtless exacerbated by living so intimately as a group in the highly stressful conditions. According to a report on a talk given later by one of the initial participants, Jayne Poynter, "the crew split into two factions about 6 months into the mission and from that point on, the two groups worked together, but could not get along. Their differences curtailed creativity and caused communication problems."

3. Management problems

Perhaps one of the most serious problems with Biosphere 2 was that it lacked a high level of scientific credibility (see "The Scientist" Vol 7, February 1993). Towards the end of the first 2-year crew's mission, Edward Bass asked the Smithsonian Institute to produce an analytical report. Among the criticisms mentioned in this report were:

  • the "lack of a well-developed, written scientific plan"
  • an "ad hoc mix of scientific initiatives of varying quality"
  • an "overconcern with proprietary information which has impeded the flow of scientific information and interaction", and
  • "possible embellishments of data".

This report recommended that a Scientific Director be appointed to oversee the development of the Biosphere 2 programme, and that the Biosphere 2 managers begin publishing and discussing their work more openly.

In fact, there was only one trained scientist among the original 8-member crew - Professor Walford, who was a trained physician and served as the crew's doctor. It is astonishing to think that such a major project should be undertaken by a crew of people who, despite their undoubted enthusiasm, were not trained scientists and who, apparently, did not keep proper scientific records.

4. Biological problems

The main biological problems in Biosphere 2 are perhaps predictable: a few common species tend to proliferate to the point where they achieve pest status, and other organisms are then disadvantaged. In Biosphere 2 the most successful insects are ants (especially the "crazy ant" - so called because of its distinctive pattern of movement), cockroaches and katydids (closely related to crickets). All of these insects thrive in warm environments with constant conditions, such as centrally heated houses where food is available. It is no surprise that they became abundant within Biosphere 2.

In contrast, the several beneficial insects that were introduced as pollinators of plants soon died out.

The end of a dream

Bold projects always have their critics, and attract intense media attention. Sadly, the catalogue of faults in the Biosphere 2 project provided plenty of ammunition, revealing fundamental flaws in the initial programme design. The last straw came when the first team of biospherians - hungry, irritable and disillusioned - admitted defeat and ended their stay. They emerged in the glare of TV cameras. The dream had become a disaster. The second crew of 7 people entered the complex, but by this stage the programme's scientific credibility was largely destroyed..

A new beginning

In 1995 the management of Biosphere 2 was transferred to Columbia University (New York City), with the option for Columbia University to buy it for a mere $1 million anytime in the next 20 years. It was also placed under firm scientific control, with an eminent Scientific Director to guide its future. The vice-Provost of Columbia University, Michael Crow, said 'We view it as the world's first teaching and research tool about global management. It's a big laboratory'

Today, Biosphere 2 continues as a visitor attraction, but now also has a major educational role in informing the public about environmental issues. The focus of research is now on climate change and the potential consequences of the predicted increases in global CO2 levels. Central to this research objective, the agroforestry zone now houses some 200 cottonwood trees (of the willow family), which can be exposed to different CO2 levels (Figure 5).

Figure 5. Cottonwood trees (Populus sp.) monitored for growth responses to different carbon dioxide levels in the agroforestry zone.

For a journalist's account of the history of Biosphere 2, see:


Analysis of Biosphere 2: notes and discussion points for students of Environmental & Community Biology 1h

We have gone briefly through the story of Biosphere 2. Now we can ask "What lessons can we learn from it?"

Some of the issues are outlined below, but you might well be able to think of others.

1. The concept of Biosphere 2: is it useful?

Setting aside the grand vision of establishing colonies on Mars, Biosphere 2 is perhaps a valuable tool for focusing attention on the relationships between humans, the resources they need, and the maintenance of a diverse and complex ecosystem. As a visitor attraction, it can have a major educational role in raising environmental awareness. And as a research tool (public access is restricted to the human habitation zone) it can be used to address important issues.

What do you think?

2. The human dimension: why did things go wrong?

I suggest that things went wrong because of a lack of proper planning. Forget about Biosphere 2 for a minute, and think instead about the international (though mainly American) space programme. How are astronauts selected, and what are their roles? It is no coincidence that astronauts are middle-aged people, with families and a nice home to go back to. They also are extremely fit, highly trained to do the technical jobs, and (ugh!) have impeccable psychological profiles. The last thing you want on a spacecraft is a "loose cannon" - someone who is unpredictable. What's more, each crew member has specific roles to play, but all the decisions are taken in Mission Control, not by debate among the astronauts themselves. There is an immense team of experts monitoring and directing every aspect of the mission, and the astronauts are, by and large, functionaries rather than decision-makers.

Contrast this with Biosphere 2. The biospherians were self-selected enthusiasts, committed to environmental ideals . There's nothing wrong with that. But the problems were many:

  • these people were not selected and highly trained for specific roles;
  • they were allowed to make their own decisions by consensus (which is OK when things are going well, but not so good when the stresses become overbearing);
  • there was no external scientific oversight - no-one to advise or turn to when things did not work.

The biospherians did not even keep proper records, so that at the end of one of the biggest environmental experiments of all time there was nothing to show for the time and money!

If you had the chance to plan the "biospherian" adventure again, how would you organise it?

3. Ecological naivety: how could they make so many errors?

Perhaps the saddest part of the whole Biosphere 2 programme was the ecological naivety shown at the outset.

Have you ever tried to maintain a garden, or have you seen a garden that was left to become overgrown? Without continual input (pruning and weeding, etc.) the strongest and most vigorous plants take over, the "exotics" are the first to disappear, and eventually only the native or near-native species survive. In contrast to this, in natural environments the plants, insects, animals, microbes and other biotic components interact in numerous ways to achieve some stability - with mutual antagonism, interdependence, competition, food webs and so on.

Most of the wilderness areas of Biosphere 2 are like gardens, with plants imported from various parts of the world, selected on the basis that they grow in particular types of conditions (e.g. hot and dry, or warm and moist) and the plant mixtures bear no resemblance to natural communities. This must severely limit the value of these areas for ecological studies in Biosphere 2.

The same naivety applied to the selection of soils. You can find a section on this in the Biosphere 2 website. But it all boils down to the following.

The soil for some of the main compartments of Biosphere 2 was a mix of (1) a silt loam from a cattle-grazing area with added organic matter, (2) coarse peat and (3) a commercial mulch from a fertiliser company. The mix would initially have had 35% organic matter.

It is not difficult to predict what would happen in a soil of this type - the soil fungi and bacteria would have a feast! The organic matter would be degraded rapidly, with release of CO2, and a marked increase in the CO2 content of the atmosphere. The atmospheric oxygen levels would simultaneously be reduced.

And, finally, why do you think that some of the crops yielded so poorly (particularly the oil-rich and protein-rich crops like peanuts and soybeans)? Yes, the answer is easy - these are leguminous crops which depend on nitrogen-fixing Rhizobium (or Bradyrhizobium in the case of soybeans) for high yeilds. These rhizobia tend to be specific for particular types of plant, and I think we can safely assume that the biospherians did not know this.

Now the big question for you to try and answer: How would you populate Biosphere 2 for ecological studies if you wanted to use Biosphere 2 as a model of Biosphere 1 (Earth)?

Footnote for Environmental & Community Biology 1h

In the ECB course you will study the Winogradsky column, a microbial model system that illustrates the interdependence of organisms.

When visitors go into the large reception centre of Biosphere 2, they find a series of display cabinets containing sealed laboratory flasks. Some of those flasks are over 100 years old, and some have bands of microbial growth like those in a Winogradsky column. They were set up by microbiologists to study how microbial communities develop in different conditions over time. Visitors are told that these flasks are biospheres in microcosm - as indeed they are. Each flask was very carefully labelled by the original scientists, recording precise details of the different incubation conditions under which these microbial communities developed.

It would be nice to end there. But now, of course, all these flasks are kept in exactly the same conditions inside the display cabinets. Perhaps that says a lot about Biosphere 2: microbial ecology (at least) was never its strong suit.

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