In 1991, eight "biospherians" were sealed inside a three-acre glass terrarium in the Arizona desert. Biosphere 2 contained a rainforest, an ocean, and a savannah. It was meant to prove that humans could colonize Mars. Instead, it proved how little we understand Earth. Oxygen levels plummeted, crops failed, the crew split into warring factions, and crazy ants exterminated the other insects. "The Glass World" documents the most ambitious ecological experiment in history. It details the scientific hubris, the psychological strain of isolation, and the humbling realization that we cannot engineer a replacement for nature. A crucial read for the climate change era, showing that "Planet B" is much harder to build than we think.