Studies of the Arctic seem to indicate that there is an imbalance in the exchange of oxygen and carbon dioxide. It is feared that climate change is a result of an imbalance in gas exchange, and if not counteracted, the biosphere could be in big trouble. How do scientists know that there are changes in the Earth's atmosphere? What do they know about past atmospheric conditions on Earth?

Scientists have conducted many studies focused on how the biosphere regulates itself. In 1985, construction began on Biosphere 2, a structure built with a closed artificial ecological system designed to study the complex web of interactions of living systems. Using Biosphere 2, scientists could alter the biosphere balance without affecting the real biosphere.