For over 150 years, plans to divert Arctic Ocean-draining rivers southwards in order to relieve an ongoing water supply crisis in central Asia have been discussed. Recent insights have identified the importance of freshwater in regulating the role of heat associated with intruding intermediate depth Atlantic water in driving Arctic Ocean sea ice decline. Here we assess the potential impact of the redirection of the Ob’, Yenisey, Northern Dvina and Pechora rivers on upper ocean density structure, and by implication, the aerial sea ice extent. A simple 1D model is applied in which freshwater content of the upper ocean water column is reduced to mimic the diversion of the rivers, and the impact on water column stratification assessed. The results show that the impact is dependent on distribution of riverine freshwater in the upper water column. If the impact of reduced freshwater is spread through the entire water column, down to the Atlantic Water Layer, the level of stratification is reduced by an average of 28%, more than the seasonal variability in stratification. However, if the changes were limited to the surface layer, the resultant reduction in stratification is less, only 17%, but the direct entrainment of deeper, warmer waters is found to occur. At a time when climate change and population growth put increasing pressure on water resources, these results show the sensitivity of a region critical to global weather and climate to anthropogenic attempts to resolve water resource issues many thousands of kilometres away.