Science Missteps: Lessons from Biosphere 2

by Lewis Loflin

In the late 1980s, Biosphere 2—a $150 million experiment in Arizona—aimed to show humans could thrive in a sealed, self-sustaining ecosystem, a test for future space habitats. Eight people entered the dome in 1991, expecting to live isolated for two years with thousands of plants to produce food and oxygen. Designed to simulate a closed system for 100 years, it lasted less than two. Oxygen levels dropped dangerously, forcing an injection of 23 tons of pure oxygen. What went wrong offers a lesson in science’s limits—and nature’s complexity.

A Flawed Ecosystem

The plan seemed straightforward: plants would convert CO2 and water into oxygen and biomass, sustaining the crew. But oxygen fell from 21% to 14% within months. Bacteria, fungi, and other decomposers in the soil—feeding on peat, loam, and plant waste—consumed more oxygen than the plants produced. Meanwhile, the dome’s 110,000 square feet of concrete absorbed CO2, skewing the balance further. Near the end, outside oxygen was pumped in to stabilize the system.

This mirrors nature’s carbon cycle: plants grow, die, and decompose, with microbes using oxygen to release CO2. Biosphere 2’s designers underestimated this. Their models assumed 4-5% organic material in the soil, but it was closer to 30%—like a forest floor, rich with decaying matter. In my local woods, inches of organic debris create acidic soil, leaching minerals from rocks. It’s Biology 101, yet the team missed it.

Why the Oversight?

The New York Times (Oct. 5, 1993, “Too Rich a Soil”) noted the project’s “New Age overtones” and reliance on powerful computers. The models failed because they didn’t account for the soil’s richness or concrete’s CO2 absorption. A proposed fix—using low-organic soil and sealing the concrete—highlighted the dilemma: richer soils boost plant growth but increase oxygen demand. In nature, this balance sustains life; in Biosphere 2, it unraveled.

Swamps offer a clue: oxygen-poor waters shift decomposition to methane, not CO2. Land plants, even in forests, contribute little net oxygen unless organic matter is removed—rare in natural systems. Biosphere 2 exposed how hard it is to replicate Earth’s complexity in a dome.

Myth of the “Lungs of the Planet”

We often hear rainforests like the Amazon produce “20% of the world’s oxygen” (e.g., rain-tree.com). Some call them the “Lungs of the Planet,” claiming 40-50% of oxygen comes from all rainforests. Yet, where’s the evidence? Forests cycle carbon: plants release oxygen, but decomposition consumes it, returning CO2. My local forest behaves the same way—growth and decay in balance. Estimates of rainforest oxygen surplus are shaky, often labeled “intuitive” rather than measured.

Oceans, not forests, dominate oxygen production—50-85% via phytoplankton, algae, and cyanobacteria (earthsky.org, June 8, 2015). These microbes built Earth’s atmosphere 400 million years ago, before land plants evolved. Rainforests likely contribute less than 10% net oxygen, if any. The “lungs” idea persists, but science suggests it’s overstated.

Greening Earth: A Surprise

NASA’s April 26, 2016, study (Nature Climate Change) found a quarter to half of Earth’s vegetated lands “greened” over 35 years, thanks partly to rising CO2—a plant fertilizer. Spanning twice the U.S.’s size, this includes the Amazon, with 35-50% more foliage. Warmer climates and CO2 boosted growth, contradicting old desertification fears. The study, from 32 authors across 24 institutions, relied on data, though its causes lean on models.

This doesn’t mean CO2’s effects are limitless—some plants thrive more than others, and benefits may taper. Greenhouses use CO2 boosts successfully, but nature adapts unevenly. The greening challenges dire predictions, yet it’s no excuse for reckless land use. Balance matters.

Lessons from Failure

Biosphere 2’s collapse—and rainforest myths—stem from oversimplification. Computer models missed soil dynamics; popular narratives exaggerated forest oxygen. Both show science can falter when assumptions outpace data. The Amazon isn’t a desert, nor is Earth oxygen-starved. Oceans, not trees, anchor our air, and greening suggests resilience.

Science thrives on facts, not intuition. Biosphere 2’s planners leaned on optimism; environmental claims often do too. Reasonable conservation makes sense—human needs and nature aren’t enemies—but policy should stick to evidence, not slogans. Earth’s systems are tougher, and more complex, than we think.