This paper explores the relationships between climate change, humanitarian crises, and humanitarian response through a review of published and grey literature. On a global level, we seek to defi ne the nature of humanitarian crisis and response and better understand connections to trends in climate change. To do this, we examine the historical evidence for associations between climate change and humanitarian crises, and then move on to a brief review of present humanitarian crises directly attributable to disasters triggered by climatological events. Finally, we look at three interrelated aspects of future trends: changing weather patterns, increasing societal vulnerabilities, and shifting demographics. We fi rst explore the anticipated direct effect that climate change will have on humanitarian crises via the frequency and geography of extreme weather events. Second, we look at how some of the major drivers of human vulnerability are likely to affect this relationship. As part of this, we examine the role of globalization, urbanization, migration, and population growth, and briefl y review examples of state-aided vulnerability