For example, the long-term consequences of ocean warming on mussel beds of the northeast Pacific are both positive (increased growth) and negative (increased susceptibility to stress and of exposure to predation) (medium confidence).’ ‘Observations performed near natural CO 2 vents in the Mediterranean Sea show that diversity, biomass and trophic complexity of rocky shore communities will decrease at future pH levels (high confidence).’ SR15 (Hoegh-Guldberg et al., 2018a) ‘Changes in ocean circulation can have profound impacts on [temperate] marine ecosystems by connecting regions and facilitating the entry and establishment of species in areas where they were unknown before (‘tropicalization’ ...) as well as the arrival of novel disease agents (medium agreement, limited evidence).’‘In the transition to 1.5°C, changes to water temperatures are expected to drive some species (e.g., plankton, fish) to relocate to higher latitudes and cause novel ecosystems to assemble