On 4 December 2017 the Australian Foreign Affairs, Defence and Trade References Committee is due to report on its inquiry into the implications of climate change for Australia's national security. Public submissions to the inquiry closed on 4 August 2017 and, at the time of writing, some 59 submissions had been made by researchers, public-interest organisations and members of the public, including a number of geographers. A topic of profound significance, climate change and national security warrants deep and sustained public engagement such as that offered by the Senate Inquiry submission process. In this Thinking Space essay, I urge geographers, working in Australia and internationally, to make ongoing contributions to such engagements. The emerging debate about climate change and national security will likely amplify following the release of the Committee's report. Geographic data and analysis pertaining to various aspects of climate change and security are needed in order to shape policy directions and support evidence-based policy making. My contention here is that contributions ought to extend not just from those working at the coalface of climate change risk, for example in political geography, but from all quarters of the discipline.