A series in the Guardian recently declared “it’s time to talk about geoengineering.” So let’s talk about it. And let us start with some simple truths about this cluster of techno-optimistic “quick fixes” which purport to somehow offset our slow progress towards zeroing out planet-warming carbon emissions.

Solar geoengineering proposals – reducing sunlight – have received the most attention, but a host of desperate schemes have been proposed in an effort to “fix” the disruption of climate caused by the growing burden of carbon dioxide human activities add to the atmosphere.