Parochial cooperation in chimpanzees is supported by social structures which encourage repeated interactions that can build trust between individuals, which consequently allows chimpanzees to cooperate with non-kin individuals on territory patrols, resource defence and lethal raids. As climate change impacts food and water availability across sites, groups that are able to maintain close in-group relations are predicted to have a competitive advantage during increasingly important inter-group conflicts over limited resources. However the impact of changing ecological conditions on group cohesion is unexplored across most sites, despite the significant observed differences in intergroup violence between chimpanzee populations being hypothesised, in part, to be due to differing ecological conditions. This project aims to examine the impact of food & water availability and predictability on chimpanzee intra-group cohesion and inter-group aggression, and to estimate the impacts climate change will have on these behaviours under current emissions pathways. I ultimately hope to explain how global change drives intergroup conflict, the impact of resource limitation on intra-group cohesion and explore the limits of parochial altruism under extreme environmental conditions.