Decline in kelp populations attributed to ocean warming has been reported in southern Australia and the north coast of Spain.’‘Kelp ecosystems will decline with the increased frequency of heatwaves and sea temperature extremes as well as through the impact of invasive subtropical species (high confidence).’ ‘Climate change will contribute to the continued decline in the extent of [...] kelps in the temperate zone (medium confidence) and the range of [...] kelps in the Northern Hemisphere will expand poleward (high confidence).’ SR15 (Hoegh-Guldberg et al., 2018a) Observed movement of kelp ecosystems not assessed.‘In the transition to 1.5°C of warming, changes to water temperatures will drive some species (e.g., plankton, fish) to relocate to higher latitudes and cause novel ecosystems to assemble