Marine biodiversity and ecosystem functioning are facing unprecedented pressures in the Anthropocene, with climate change being a primary stressor. To understand the biological response mechanisms along coastlines, the international scientific community requires coordinated action, integrating obervations through observatory networks and spatially extensive experiments using standardized approaches over broad geographic scales. Currently, however, a multinational, integrated approach is lacking, with little application of standard methodologies or data sharing across countries. Changes in the abundance, distribution and competitive dominance of rocky intertidal organisms are useful sentinels of climate change because these communities are easy to observe and long-term time series exist. Europe is in a prime position to lead by example, building on the extensive history of sustained observations and experimental research to establish an integrated network of studies and monitoring programmes. These will improve our understanding of how organismal responses translate into biogeographic range shifts, and generate more biologically realistic predictions of future climate change impacts with which to design mitigation, adaptation and conservation strategies