How the Biosphere 2 experiment changed our understanding of the Earth

Biosphere 2 is a unique scientific facility located in the Arizona desert. Built in the 1980s, it is a huge glass structure filled with different environments that mimic those found on Earth, such as a rainforest, a desert, a savannah, and even a large ocean. The idea behind Biosphere 2 was to see if people could live in a completely closed system, where everything they needed—food, water, and air—had to be produced and recycled inside. In 1991, eight people, called biospherians, entered the sealed building and tried to survive for two years without any help from the outside world.

The experiment was much harder than anyone expected. The oxygen levels inside the building dropped, making the biospherians feel weak and sick. Carbon dioxide levels rose, and many of the animals and insects that were supposed to help the plants grow died off. Without enough pollinators, some plants could not make seeds. The biospherians grew their own food, but it was not enough, and they lost a lot of weight. Eventually, the team had to bring in extra oxygen from outside, which made some people say the project had failed. The media at the time was very critical, calling the experiment a flop and saying it was not real science.

However, over time, scientists have come to see Biosphere 2 in a new way. The experiment taught us just how complex and delicate Earth's systems are. For example, the soil in Biosphere 2 was so rich that bacteria and fungi used up a lot of oxygen, which the young plants could not replace fast enough. This showed how important even the smallest parts of an ecosystem are. Today, Biosphere 2 is used to study how climate change affects different environments. Scientists can create droughts or heatwaves inside and see how plants and animals respond. The main lesson from Biosphere 2 is that Earth is incredibly hard to copy, and we need to protect our planet because it is our only home.