How do the unique chemical and physical properties of water make life on earth possible?

1 Answer
Sep 21, 2015

Water keeps chemistry working, nutrients moving, temperatures stable, bodies of water from not completely freezing through.


This 4 min youtube video by RicochetScience does an amazing job explaining and visualizing the unique properties of water and how it helps life exist:

So instead of paraphrasing the video, let's provoke some creative thoughts by thinking through what would happen to living beings and life on earth if the unique properties of water were flipped around to their opposite extremes:

Hey, it's OPPOSITE DAY for Water:

  • Water is NOT a universal solvent: substances that would usually dissolve in water no longer do; they become like sand in water instead. Almost all chemical reactions necessary for life (which would usually occur when reactants dissolve and mix together) stop or drastically slow down.

  • Water has LOW cohesion and adhesion: waste and nutrients are no longer transportable around an organism's circulatory system (i.e. your bloodstream) as carried by water. Plants would quickly droop and die because capillary action is no longer possible, taking away their ability to carry water and nutrients up against gravity from the soil. Insects that usually walk on water would immediately sink to the bottom and drown.

  • Water has LOW heat capacity: instead of moderating temperature levels to a pleasant, livable range, water’s temperature would rise and fall more rapidly and to greater extremes (like aluminum, which has low heat capacity) causing temperatures around the world to swing from extreme from extreme as the sun rises and falls. Human bodies, consisting of 55-75% water, would also face the same extreme swings.

  • Ice (solid water) is MORE dense than liquid water: If everything above wasn’t bad enough, if water in the solid state was more dense than in the liquid state, ice would no longer float. Without floating ice being a protective layer that insulates all the liquid water below, water would turn into ice from the bottom up and cause all water-based life to freeze and die.

This is not a comprehensive listing of everything that would happen; it's just a fun and usefully absurd thought experiment to challenge your understanding of exactly how and why water is so important to life.

Got some examples of your own? Please share!