The idea of solar geoengineering is an obstacle to the imperative of emergency mitigation. Unless global emissions are put into “immediate and rapid decline” 1.5C and 2C are out of reach (IPCC Chair H Lee, 2021 UN COP26 Glasgow). The fact that solar geo-engineering does not stop ocean acidification is enough to disqualify it. Research shows it is unlikely to affect deep ocean heat and so de-oxygenation. Proposals are to cool the Earth while emissions are declining, but that would allow radiative heat forcing to keep increasing masked by surface cooling. Removal of cooling would result in a greatest ever abrupt surface heating catastrophic to all life.