More than 90 percent of the warming that has happened on Earth over the past 50 years has occurred in the ocean. Not all of that heating is detectable yet at the surface
How we know global warming is still happening
Change in global upper-level (0-2000 m) ocean heat content since 1958.
Global climate change
Effects of climate change on oceans - Wikiwand
2014 State of the Climate: Ocean Heat Content
How Climate Change is Impacting Ocean Temperatures
How do we know climate change is real? - Part 1 - Solen
Does ocean cooling prove global warming has ended?
Warming trends increasingly dominate global ocean NOAA Pacific Marine Environmental Laboratory (PMEL)
Warming of the world ocean, 1955–2003 - Levitus - 2005 - Geophysical Research Letters - Wiley Online Library
Ocean heat content - Wikiwand