This paper argues that climate change now constitutes a near- to mid-term existential threat to human civilisation. However, this outcome is not predetermined. A critical flaw in current climate risk assessment is the reliance on conservative scientific projections that underplay extreme possibilities. To avoid catastrophic futures, we must adopt a new approach to climate-related security risk — one that accounts for high-impact, low-probability “fat-tail” risks. The paper presents a 2050 scenario in which escalating climate disruptions lead to widespread societal collapse, potentially irreversible for centuries. Preventing such outcomes demands a rapid transition to a zero-emissions industrial system, requiring emergency-level global mobilisation akin to wartime efforts.
Climate change is already amplifying existing national security risks, acting as a threat multiplier that fuels cycles of instability, conflict, and forced migration. For example, food and water insecurity exacerbated by droughts and harvest failures has contributed to unrest and displacement in regions like the Middle East and Sahel. Addressing these challenges requires moving beyond traditional forecasting and embracing scenario analysis to better navigate uncertainty. Effective climate security planning hinges on recognising both the limits of current science and the urgency of preparing for worst-case outcomes before they materialise.
Admiral Chris Barrie AC (Retd) authored the foreword, highlighting climate change as a current and existential threat to human survival. Drawing on the Australian Senate’s 2017-18 inquiry, he emphasises that global warming ranks just behind nuclear war as the greatest danger to humanity. Barrie underscores the urgent need for a fundamental shift in human behavior and leadership to address this crisis, warning that without immediate, collective action, the future looks dire. He calls on intelligence and security agencies to prioritise climate risks above traditional geopolitical threats, framing climate change as a paramount national security issue demanding strong, decisive responses.
