Alarming predictions have been made about the potential for climate change to fuel war and other forms of violent or social conflict, particularly due to resource scarcities (including food, water and energy) driven by climate change. This article first charts the likely security risks arising from the effects of climate change, including traditional security threats (such as armed conflict) and non-conventional or ‘human security’ risks (particularly as regards access to resources – food, water, energy – that are essential to human dignity). The article then examines the spectrum of international law implications of the relationship between climate change and these forms of insecurity. While the spectre of ‘climate wars’ is fanciful, the effects of climate change are likely to stimulate domestic and global tensions and to aggravate other underlying causes of conflict. Conventional and human security problems will arise from distributional conflicts over scarce resources (food, water, energy, land and seas), disputes over maritime boundaries, competition in the polar regions, pressure upon public health infrastructure, changing migration patterns, potential for radicalisation, and systemic stresses upon weak States, economies and social orders. Such consequences do not inexorably lead to outbreaks of violence or political instability, but they may be contributing factors given the right constellation of conditions. With the processes of climate change already well underway, even the rapid conclusion of an effective post-Kyoto global climate change regime (such as a carbon tax or cap-and-trade scheme) would not be sufficient to avert the security risks that are already in formation. It is vital, therefore, to consider the range of ways in which public international law can be marshalled to prevent, contain and remedy the consequent security threats. Problems of identifying relevant primary obligations and attendant problems of causation limit the utility of relying upon principles of State responsibility to confront climate-related security risks. More promising are the specialised branches of international law (such as environmental law and the law of the sea), some of which offer prospects for responding to the challenge and others which would require more radical refashioning. Engaging the specialised branches of international law enables a thicker, more systemic response to the security risks attending climate change and is likely to prove more effective than relying on singular institutions (such as the Security Council) or normative frameworks (such as a new global climate deal). The costs of modifying international law in these ways is undoubtedly less than the human and financial costs which will likely ensue from resource conflicts and sovereign competition aggravated by unmitigated climate change