Just a Drop to Drink

According to UN Water, "Each of us needs to drink 2 to 4 litres of water every day. But it takes 2000 to 5000 litres of water to produce one person's daily food." If that seems like a lot, it is. But it's funny how much depends on your perspective. A graphic from the USGS shows what it would look like if all the water on Earth were gathered into one drop. On A Few Things Ill-Considered, Coby Beck discusses the even smaller drop that represents all fresh water. Coby writes, "A full 74.5% of that much smaller ball is locked away in ice caps and glaciers and 24.7% is groundwater (much of that out of reach). There is only .56% of the world’s freshwater circulating in lakes, rivers, rainfall, soil and the biosphere." The sight of so little water against the rocky backdrop of Earth might inspire some to keep our water clean. But on Starts With a Bang, supervillain types dream of apocalypse. Ethan Siegel writes, "The ability to have liquid water is relatively rare: we need the proper temperatures and the proper pressures!" Without our 5.3 quadrillion ton atmosphere, there would be no water on the surface of the Earth, and without the magnetosphere generated by the planet's core, we would have no atmosphere. Ethan continues, "Charged particles are bent by magnetic fields in very predictable ways [...] if we could create a large enough magnetic field on Earth, we could poke a hole in the magnetosphere and allow the solar wind to strip our atmosphere away!"