I’ve always loved this paper, for its particular combination of heterodoxy and emphasis on testable hypotheses. There are so many things we don’t know about past human civilizations that have left non-geological markers (who were the “Sea People,” the full story of Petra, tons of undeciphered ancient scripts, etc.) that it doesn’t seem terribly strange that an industrial civilization could have bloomed, died, left few traces, and what traces they did leave are the kind only a geochemist or paleoclimatologist might notice.