Journal
<p>Phenological, biogeographic and community shifts are among the reported responses of marine ecosystems and their species to climate change. However, despite both the profound consequences for ecosystem functioning and ser- vices, our understanding of the root causes underlying these biological changes remains rudimentary. Here, we show that a significant proportion of the responses of species and communities to climate change are determinis- tic at some emergent spatio-temporal scales, enabling testable predictions and more accurate projections of future changes.We propose a theory based on the concept of the ecological niche to connect phenological, biogeographic and long-term community shifts. The theory explains approximately 70{%} of the phenological and biogeographic shifts of a key zooplankton Calanus finmarch- icus in the North Atlantic and approximately 56{%} of the long-term shifts in copepods observed in the North Sea during the period 1958–2009.</p>