Climate change is affecting marine ecosystems. Changes are evident in both warming and acidification of the oceans. These changes strongly influence ocean climate, biogeochemical cycles and fundamental biological processes. Phytoplankton form the basis of aquatic food webs, providing ocean services such as primary production, oxygen generation and carbon cycling. Predicting changes in these services requires an improved understanding of how phytoplankton will respond to changes in habitat as a result of environmental stressors. Quantification of the response of phytoplankton to climate change is crucial for understanding the long-term stability of marine ecosystems, and to enable their sound management. Computational modelling representations of phytoplankton responses to climate change are mainly based on short-term experiments, which do not provide information on the evolutionary potential of these organisms. Science sometimes develops independently of human needs, so scientific products do not always answer societal questions. With this project we aim to understand the evolutionary responses of marine phytoplankton to water warming and acidification, focussing on two model organisms of relevance also for human society: Skeletonema marinoi and Emiliania huxleyi. These are globally distributed algae, often producing abundant blooms in coastal areas. The knowledge gained in this project on the response of the two species in the context of climate change will be incorporated into the computational models, and will provide any interested organisations (stakeholders) with the relevant information needed (decision making on new environmental policies, adaptation of the fishing industry to future conditions, etc.).