This thesis draws on the climate-conflict research field to explore the question how does climate variability affect interstate conflict? This thesis contributes to various gaps in previous research by studying interstate conflict while most climate-conflict research investigates internal conflict, by using a new operationalization of climate variability as sea ice extent, and by studying an understudied case, the Arctic region. The theoretical argument consists of two parallel processes, a background mechanism focused on long-term climate change and a main mechanism focused on short-term climate variability. Increased climate variability is theorized to increase access to rivalrous resources, thereby increasing their saliency and leading to interstate competition. This increases each state’s utility of fighting, increasing the risk of bargaining failure and hence interstate conflict. The background mechanism theorizes that increased climate change will increase the risk of commitment problems, thereby contributing to bargaining failure and interstate conflict. I test the hypothesis that decreased sea ice extent increases the likelihood of militarized interstate incidents through a large-N quantitative study. Overall, the findings are inconclusive but with a low degree of support for the hypothesis.