In national and international arenas, climate change and its impact are often framed as a grave global security threat, causing chaos, conflict and destabilising countries. This framing has, however, not resulted in exceptional measures to tame the purported threat. This article examines the workings of such attempts at climate securitization and interrogates its lack of success in galvanizing exceptional action. We do so informed by two cases, which both point to the instrumental nature of these attempts to securitise climate change, often with the intention to use alarming framings to promote rather mundane actions. Also, both cases show that the strategic nature of the speech acts and the aim to make them sound highly dramatic, makes audiences sceptical, thereby weakening their success. Our first case sketches how the United Kingdom’s Foreign and Commonwealth Office framed climate change as an existential security threat with a view to enrolling other countries to promote collective climate action. Whilst partially successful on an international level, key audiences – the BRICS countries – remained unconvinced, and the discourse lost support at the domestic level. Likewise, the Dutch Delta State Advisory Commission securitized climate to instil a sense of urgency in the domestic target audience. While initially generating blanket support for the costly spatial Delta interventions it advocated, the mood soon turned. Both cases show that while the tendency to ‘securitize’ climate may be on the rise, instrumental securitization can easily backfire like a ‘policy boomerang’, reinforced by parallel economic and political changes.