Climate change is upon us and its physical effects have started to unfold. That is the broad scientific consensus expressed in the Fourth Assessment Review of the Inter-governmental Panel on Climate Change. This report takes this finding as its starting point and looks at the social and human consequences that are likely to ensue – particularly the risks of conflict and instability. Hardest hit by climate change will be people living in poverty, in under-developed and unstable states, under poor governance. The effect of the physical consequences – such as more frequent extreme weather, melting glaciers, and shorter growing seasons – will add to the pressures under which those societies already live. The background of poverty and bad governance means many of these communities both have a low capacity to adapt to climate change and face a high risk of violent conflict. Many of the world’s poorest countries and communities thus face a double-headed problem: that of climate change and violent conflict.