Books inevitably reflect the ideas, prejudices, background and the obsessions of their author. As I have no wish to put off prospective readers by indulging in a tangential autobiographical digression, let me just say that I didn't mean to become a ‘security expert’. Hitherto my principal interests were ‘international political economy’ and, more recently, the politics of climate change. I should confess that I cannot claim specialist knowledge in the underlying science of global warming, but that has not stopped me from thinking about the political and security implications of climate change and the impact it is having on the natural environment upon which we all ultimately depend. It shouldn't stop anyone else either. On the contrary, one of the animating ideas that run through this book is that many of the policymakers and strategic thinkers who shape security policy have a remarkably impoverished and limited view of the nature of security in what we now call the Anthropocene. Such views were arguably always problematic; now they are indefensible.

It is the recognition that our collective impact on the natural environment presents the greatest security threat we have ever faced as a species that has encouraged me to think about its increasingly obvious security implications. To be fair, the potentially catastrophic consequences of climate change have not escaped the notice of mainstream strategic thinkers, or the policymakers they advise. Their responses are often depressingly familiar, however, and reflect their intellectual assumptions and prejudices, even if they are often unrecognized. Indeed, the ‘strategic cultures’ within which ideas about, and even psychological dispositions toward, security are formed play a profoundly important and limiting role in what sorts of policy are deemed appropriate, ‘rational’ or feasible by the people who dominate the debates in this area. More importantly, they have got us to where we are today: unhappy, insecure, facing the – still unlikely, but real – possibility of great-powers’ war and a natural environment that may not be capable of supporting human life in the foreseeable future; or, at the very least, not in the numbers and style to which we are accustomed.