3 Global mean SST has increased since the beginning of the 20th century by 0.88℃ , and it is virtually certain that the global ocean has warmed since at least 1971 . A key characteristic of ocean temperature change relevant for ecosystems is climate velocity, a measure of the speed and direction at which isotherms move under climate change , which gives the rate at which species must migrate to maintain constant climate conditions. It has been shown to be a useful and simple predictor of species distribution shifts in marine ecosystems . Median climate velocity in the surface ocean has been 21.7 km per decade since 1960, with higher values in the Arctic/sub- Arctic and within 15° of the Equator . While climate velocity has been slower in the mesopelagic layer  than in the epipelagic layer  over the past 50 years, it has been shown to be faster in the bathypelagic  and abyssopelagic  layers , suggesting that deep-ocean species could be as exposed to effects of warming as species in the surface ocean .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report