The conclusion that our climate is drastically changing is considered indisputable by the Intergovernmental Panel on Climate Change. However, generalisations on the impact of multiple rapid environmental changes on living organisms are still rather difficult. Ocean warming (OW), deoxygenation (hypoxia) and acidification (OA) represent major threats to marine organisms, causing energetic and homeostatic challenges that can lead to increased mortality and reduced fecundity. In addition, as species from different climatic regions possess different levels of tolerance and plasticity to OW, populations' and species' responses to multiple global changes along environmental gradients are expected to vary too. However, how they will vary represents an important knowledge gap. Within this context, to support decision makers responsible for the conservation of biodiversity and the adaptive-management of natural resources, it is imperative we acquire a firm understanding of the: (i) cellular and whole organisms physiological responses through which different species will be able to cope with multiple environmental changes, (ii) the ability of populations and species living along environmental gradients to buffer potential negative effects of global changes through transgenerational phenotypic plasticity (TGP), and (iii) populations' and species' ability for rapid adaptation to future ocean conditions. Unfortunately, the majority of studies to date on global change biology of marine metazoans have focused on single life stages of single populations of single species' short-term responses, often to single stressors. With this said, in the past six years, I have developed an innovative research programme investigating marine metazoans TGP and rapid adaptation to global change drivers. I also demonstrated the importance of considering local and regional adaptation in defining populations' physiological sensitivity to ongoing single global change drivers and shed light on physiological pathways of impact. I am now in the unique position to propose a transformative, integrative and multidisciplinary research programme aiming at creating a synthesis among the research fields of Global Change Biology, Macrophysiology and Ecophysiology. I propose to employ for the first time in marine animals a multi-omics/multi-layer approach to unravel the functioning, plasticity and ability for rapid adaptation of the complex network of metabolic pathways underpinning organisms' fitness responses. Using this framework on multiple populations living along environmental gradients in calanoidea copepods, which are essential keystone species to marine food webs linking primary producers to fish and top predators, I will test the hypothesis that >.