All the world’s water and air, to scale (from here):
The sphere is much smaller still if only counting fresh water.
Anyway, the lesson is that life is precarious and precious.
In times of plenty we get comfortable. We forget that life is actually terrifyingly precarious (see, e.g., #252 here).
Say that little sphere’s-worth of water is taken away. Then what? Then everything dies. It’s the end. Or can we manufacture artificial water by now?