With the current rate of climate change, marine ecosystems will be profoundly reshaped by sea warming. Understanding the impacts of climate change on marine species is thus of paramount importance to devise effective conservation measures. However, this requires a powerful approach that would allow to examine the past and predict the future responses of species to climate fluctuations. Genomic tools have played a central role in evolution and ecology and have improved our understanding of the past demographic and adaptive trajectories of species in changing environments, while genome-informed simulations can model species responses to future climate change. Yet, the few studies that have combined genomic data and simulations have only focused on single-species analyses, limiting our understanding of the broad spatial, ecological and taxonomical effects of climate change. To fill this gap, we will develop a temporal macrogenetics approach to investigate the impacts of climate change on the marine ecosystem of the North Atlantic. Using publicly available genomes for multiple vertebrate and invertebrate species, we will first examine the demographic responses of marine species to past climate fluctuations of the Pleistocene. Secondly, using published and newly-generated modern and historical genomes, we will track temporal changes in detrimental and adaptive genomic variation over the past few centuries, a period characterised by rapid climate warming and increased human pressure. Finally, based on these results and using species distribution modelling and forward simulations, we will predict the future demographic and genomic responses of North Atlantic marine species under various sea warming scenarios.