This paper aims to document a scientific linkage between the underground testing of nuclear weapons and global warming. An empirical analysis of CO2 and fossil- fuel data post-1945 suggests that global warming is not clearly attributable to greenhouse gas emissions alone. Our data indicates beyond statistical doubt a direct linkage between the rise in CO2 levels and underground bomb testing; rendering adverse consequences like global warming, radioactive contamination of terrestrial and marine ecosystems, and major disruptions to temperature patterns around the world. The derivative carbon footprint of underground nuclear testing is colossal and can bring about devastating human-induced climate changes which are not just massive but potentially irreversible.