What is the evidence that scarcity and shocks in freshwater resources can cause conflict instead of promoting collaboration

Anthropogenic activities such as the combustion of fossil fuels, land-use change and intensive agriculture are increasingly influencing the Earth‘s climate and exerting pressure on ecosystems. These changes have amplified the risk of scarcity and shocks (discrete and sudden events) in natural renewable resource (henceforth, NRR) scarcity across the spectrum of spatial scales. \nThe interplay between freshwater scarcity and conflict/collaboration is the most prominent and referenced of the environment-conflict issues in the Third and Fourth Assessment Reports of the IPCC. Discussions with the review user-group, confirmed that a systematic mapping of the literature in this particular field was a priority.