Global climate change is causing widespread shifts in species distributions, community composition, and ecosystem services (Pereira et al., 2010, Pereira et al., 2012). In the oceans, warming is shifting species distributions toward cooler waters (Molinos et al., 2016, Pinsky et al., 2013) and stressing sessile species in-situ (e.g. coral bleaching (Donner et al., 2017), while acidification is already impacting some cold-water species (Manno et al., 2017) and threatening many other species and ecosystems (Pecl et al., 2017, Sunday et al., 2017). Patterns of climate change at regional scales are far less well understood, not least because global climate signals interact with regional processes to produce more complex patterns. Nonetheless, there are many relevant data and regional climate models for Scandinavia that have addressed these issues. Recent analysis shows that over the last 150 years or so the Baltic1 has warmed by 1-2 degrees (Meier et al., 2014), and there have been marked shifts in the seasonality of Baltic waters, with earlier onset (and longer periods) of warm temperatures over the last 4 decades (Kahru et al., 2016). Results from a comprehensive suite of projections from regional atmosphere:ocean models (Meier et al., 2012a, Meier, 2015, SMHI, 2017) show even greater future change, with average additional warming by 2-4°C average additional freshening by up to 2 salinity units, and average decrease in deep oxygen concentrations by 0.5-4 mg O2.ml-1 by the end of this century (Meier et al., 2012c, Neumann, 2010, Vuorinen et al., 2015). These models also project that changes will be highly heterogeneous over scales of 10’s to 100’s of kilometers. Model projections indicate with a relatively high degree of certainty that 5080% of winter sea ice in the northern Baltic will be lost by the end of the century (Andersson et al., 2015). These shifts in seasonality and climate are already having effects on some species in Swedish coastal waters (Appelqvist et al., 2015, Appelqvist & Havenhand, 2016), and are projected to have even greater impacts in the coming decades (Meier et al., 2012b). Notable among these projections are freshening-driven shifts in the range boundaries of key species such as eelgrass, blue mussels, and cod (Vuorinen et al., 2015; and see Fig 1), substantial ice-loss driven reductions in populations of ringed seal (Sundqvist et al., 2012), and combinations of changing ice-cover, salinity, and temperature leading to range-shifts of key crustacean species (Leidenberger et al., 2015). Although the literature on climate-change effects in Swedish coastal waters is still relatively small, it is clear that climate change is already having effects on Swedish marine species, and that projections indicate greater effects in coming decades [with the caveat that there is likely a strong reporting bias toward significant effects: studies that found small, or no, effects of projected climate on species distributions in Swedish coastal waters (e.g. Laugen et al., 2015) are less frequently reported]. In addition to direct effects on individual species, climate change also has indirect – and potentially cascading – effects on interacting species in the ecosystem, which for the Baltic may be substantial (Vuorinen et al., 2015). Thus, the likelihood of substantive shifts in marine ecosystem composition and diversity throughout Swedish coastal waters is high (Elliott et al., 2015, Niiranen et al., 2013). These likely shifts in ecosystem composition and diversity are critical because many marine protected areas are established to protect key species, and because ecosystem functioning and resilience to climate change are strongly related to biodiversity (Gamfeldt et al., 2015, Lefcheck et al., 2015). Loss of biodiversity has been shown to reduce ecosystem functioning, leading to loss of productivity, resource collapse, and greater sensitivity to disturbance (Cardinale et al., 2012, Worm et al., 2006). Thus, in a broad sense, biodiversity confers resilience on ecological communities (Campbell et al., 2011) and is therefore also critical to the long-term sustainability of ecosystem services in the face of environmental change (Loreau & Mazancourt, 2013).