The oceans are tricky. The SCALE and the MEDIUM changes the way HEAT behaves in the Oceans. It can be very unintuitive.
The mention of a "pot" is an apt one because it "frames" our thinking into a "false" pattern of understanding. When you dump HEAT into WATER in a pot, the HEAT is rapidly distributed throughout the pot.
2nd Law of Thermodynamics at work, right?
It doesn't work that way in an ocean. The HEAT in the ocean starts at the top. 90% of the ENERGY the Earth captures from the Sun goes into the Oceans, right at the top.
Now, the BOTTOM of the Oceans is very COLD, ALL the time. A constant 0C to 3C, just above freezing.
Water is REALLY WEIRD.
It doesn't compress under pressure and it EXPANDS when it freezes. Which means that ice FLOATS on the surface instead of sinking to the bottom.
Even at the bottom of the ocean, water stays fluid. This water is VERY COLD.
But, the HEAT from the surface should warm up the OCEAN equally. Why isn't it?
Because, WARM water molecules also EXPAND and so, warm water also FLOATS upward.
The medium of WATER carries the downward moving HEAT back up to the surface. Heat convection doesn't deeply penetrate in the oceans.
About 80% of the heat in the oceans is in the top 700m (2,300ft). That's the 1st "convection cell".
About 20% of the surface heat is in the 2nd convection cell. This cell starts around 700m and extends downwards to about 2,000m (6,500ft).
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Scientists recently found that the rate of warming in the top 6,500 feet of the ocean over the past few decades was about 40 percent higher than previously estimated.
Which is the proxy measure indicating that "Climate Sensitivity" estimates are about 40% too low.
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Basically, NO HEAT from the surface reaches down into the ocean waters below about 6,500ft (2000m). There just hasn't been enough HEAT in these deep waters to cause a 3rd convention cell to form.
That may be changing.
Even the deepest, coldest parts of the ocean are getting warmer. - 2020
Thermometers moored at the bottom of the Atlantic Ocean recorded an average temperature increase of about 0.02 degrees Celsius over the last decade, researchers report in the Sept. 28 2020 Geophysical Research Letters.
That warming may be a consequence of human-driven climate change, which has boosted ocean temperatures near the surface (SN: 9/25/19), but it’s unclear since so little is known about the deepest, darkest parts of the ocean.
“The deep ocean, below about 2,000 meters, is not very well observed,” says Chris Meinen, an oceanographer at the U.S. National Oceanic and Atmospheric Administration in Miami.
The deep sea is so hard to reach that the temperature at any given research site is typically taken only once per decade.
Meinen’s team measured temperatures hourly from 2009 to 2019 using seafloor sensors at four spots in the Argentine Basin, off the coast of Uruguay.
Temperature records for the two deepest spots revealed a clear trend of warming over that decade.
Waters 4,540 meters below the surface warmed from an average 0.209C to 0.234C,
Waters 4,757 meters down went from about 0.232C to 0.248C.
This warming is much weaker than in the upper ocean, Meinen says, but he also notes that since warm water rises, it would take a lot of heat to generate even this little bit of warming so deep.
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There is a LOT of ENERGY in the Oceans.
