Mature Technosphere / Class V Planet

Frank, Carroll-Nellenback, Alberti and Kleidon's (2018) five-class scale ranks planets by the thermodynamic complexity of their coupled systems; the speculative Class V has a technological civilization "in a stable relationship" with its host world's biosphere, geosphere and atmosphere. Frank, Grinspoon and Walker (2022) describe the step as moving from an immature technosphere (Haff's "synthetic corona" metabolizing fossil fuels, forcing coupled systems into states it cannot regulate) to a mature one whose feedback loops are "intentionally modified" to keep the whole system stably productive — by analogy with the Archean→Proterozoic maturation of the biosphere. Maughan's claim is that simulation (climate models, digital twins) is the organ by which a technosphere matures; only mature technospheres last long enough to be found by SETI.