Why Is The Bottom Of The Ocean So Cold? - Science ABC

The bottom of the ocean is so cold because cold water is denser than warm water, so it sinks into the depths, while the latter remains close to the surface. Also, water at the surface becomes cold primarily due to evaporation, after absorbing thermal energy from the sun. As water becomes cold, it sinks and is replaced by warm water. Plus, the sun’s radiation does not heat the lower levels of the ocean, as the rays are completely dissipated in the upper layers.

Cold water is denser than warm water, so it sinks into the depths, while the latter remains close to the surface. Also, water at the surface becomes cold primarily due to evaporation, after absorbing thermal energy from the sun. As water becomes cold, it sinks and is replaced by warm water. Plus, the sun’s radiation does not heat the lower levels of the ocean, as the rays are completely dissipated in the upper layers.

The inner parts of the Earth are constantly being heated up due to the leaking of thermal energy from the radioactive decay of particles in the planet’s core. Crude logic would dictate that, as a result of this internal heating, the water temperature at the ocean floor should rise too.

Also, it’s a well-known fact that pressure increases proportionally as one goes deeper into an ocean.

One would also logically say that this increased pressure should warm up the ocean water to insanely high temperatures at great depths, but interestingly enough, nothing of the sort happens. In fact, the reality is the exact opposite of what one would assume. The water at the bottom of oceans is very cold (just a couple of degrees above freezing). All of this begs the question: why does ocean water become increasingly cold as one goes deeper?

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