Theory of population dynamics predicts that environmental autocorrelation increases extinction risk. Recent work by Engen and colleagues confirms this and demonstrates how the spatial extent of population synchrony is
influenced by dispersal. However, in a new study, Gonzalez and Holt demonstrate that environmental autocorrelation causes substantial increases in the size of
populations with negative growth rates, provided that they are sustained by immigrating dispersers. These new findings could change our view of dispersal and sink populations, whilst providing an explanation for previously enigmatic population outbreaks.