The Arctic has been identified by scientists as a relatively promising venue for controversial ‘solar geoengineering’ – technical schemes to reflect more sunlight to counteract global warming. Yet contemporary regional security dynamics and the relative (in)significance of climate concerns among the key Arctic states suggest a different conclusion. By systematically juxtaposing recently published schemes for Arctic geoengineering with Arctic security strategies published by the littoral Arctic states and China we reveal and detail two conflicting security imaginaries. Geoengineering schemes scientifically securitise (and seek to maintain) the Arctic’s ‘great white shield’ to protect ‘global’ humanity against climate tipping points, and invoke a past era of Arctic ‘exceptionality’ to suggest greater political feasibility for research interventions here. Meanwhile, state security imaginaries understand the contemporary Arctic as an increasingly contested region of considerable geopolitical peril and economic opportunity as temperatures rise. Alongside the entangled history of science with geopolitics in the region, this suggests that geoengineering schemes in the Arctic are unlikely to follow scientific visions, and unless co-opted into competitive, extractivist state security imaginaries, may prove entirely infeasible. Moreover, if the Arctic is the ‘best-case’ for geoengineering politics, this places a huge question mark over the feasibility of other, more global prospects.