An unnamed scholar living in the neo-communist Second People’s Republic of China centuries after the fall of modern democratic nations. As a synthetic-failure paleoanalyst, they specialize in studying the historical collapse of past societies. They write a formal academic essay reviewing the "Period of the Penumbra" to explain why the 21st-century Western world failed to prevent its own environmental and social destruction despite having the necessary scientific knowledge. The scholar acts as a critical voice analyzing past capitalistic and scientific failures.

A Japanese genetic engineer who develops a unique "lichenized fungus" known as Pannaria ishikawa. She operates during a period of massive global environmental crisis, taking direct action to mitigate atmospheric carbon levels. Her unauthorized environmental interventions place her at odds with the Japanese government, which brands her a criminal, yet she earns the admiration of everyday citizens who view her as a hero. She represents practical action confronting bureaucratic paralysis.

An earth scientist, historian of science, and co-author of the text who participates in an interview in the book's appendix. She uses the fictional framing to explore the real-world barriers to climate action, particularly focusing on the dangers of science denial and market fundamentalism. She advocates for interdisciplinary scientific methods, arguing that strict reductionism prevents society from addressing complex environmental threats.

A historian of science and technology who co-authors the essay and features in the concluding interview. He brings expertise in technological history to the project, helping construct the satirical concept of the carbon-combustion complex. He defends the narrative's optimistic view of human adaptability while severely criticizing the industrial reliance on fossil fuels and the socio-economic models that support them.

An interviewer from Columbia University who questions the authors about their novella. He pushes them to explain their narrative choices, their use of satire, and their critiques of American capitalism and scientific standards. His questions allow the authors to clarify their socio-political arguments and address potential reader criticisms directly.