Thinking about all the stories about the current droughts, and how climate change is disrupting everything and how likely it is to lead to mass migrations and water wars and all…
Suppose we decided to be really “fair” and parcel the Earth’s supply of water out evenly to every human being. Ignore that water is constantly in motion, being reused and recycling around – we just take the total amount that exists at one moment. We’ll also ignore that there are a zillion animals and plants that might be considered to have some claim on water. (Hey, ‘screw them’ seems to be our reaction to non-human species rights in general, right?)
For ‘practical’ reasons, let’s give each human three ‘containers,’ one each for fresh water, salt water, and ice. What I really want to know is, how big would those containers be?
Use any measurement system that seems appropriate. Would we each get a swimming pool’s worth of fresh water? 15 oil tankers full of salt water? A cube of ice 60 meters per side?
Hmmm. Do we need another container for the moisture in the atmosphere? Or maybe we condense that somehow and add it to the freshwater tank.
Using the figures from the Wikipedia page, and assuming a population of 8 billion, I get the following volumes per person:
1.7 x 10^8 m^3 salt water
3.0 x 10^6 m^3 ice & snow
1.3 x 10^6 m^3 fresh water
530 supertankers of salt water (67,000 Olympic swimming pools)
10 supertankers of ice & snow (1,200 Olympic swimming pools)
4 supertankers of fresh water (520 Olympic swimming pools)
Wow. My no-real thought estimates were off by a factor of !500! on the fresh water, hey, but “only” about 35 on the salt water.
Thanks for tackling the math end!
That is a stunning image!
It’s all in which way you’re looking, isn’t it? I was stunned at how LARGE the answers were numerically, and seconds later stunned at how small the answer is when comparing to the planet.
It looks like, proportionately, the Earth has just about the same amount of water as a bowling ball that had been dipped in a bucket of water and pulled right out!
We seem to be using up that groundwater awful fast. Is your 99% of water being underground account for usage? Does it mean it is accessible?
Researchers found that 30 percent of the Kansas portion of the Ogallala Aquifer has already been pumped out, and another 39 percent will get used up in the next half-century at existing rates. Kansas, clearly, is on the fast track to depletion. As a result, agriculture production is likely to peak around 2040 and decline after that. SOURCE
Do they want a measure of all the water that is possible to squeeze out of the earth or a measure of all the water that each human could reasonably have access to?
An H2O molecule in the mantle, while part of the earth, is of little use to a human on the surface (and it seems there is a helluva lot of water there which may be a great deal of your 99% but we will never access it).
Personally, I think both data points are interesting.
To be clear, the figures I gave above for the total amount of fresh water only included fresh groundwater, which exceeds the amount of surface water by about 100-fold. Although not immediately accessible, I believe this entire volume is all in dynamic contact with the surface. Total groundwater may fit some broader definition of “accessible”.
These figures did not include water that may be trapped much lower in the mantle. I think this is more speculative, there are no precise estimates for this.
I had read somewhere that far from the ocean deeps, if the earth were the size of a billiard ball, it would have a barely discernable film of moisture on it. That illo drives the point home.
Significantly, about 1/60th of the oceans’ volume is piled up on Antarctica.
That’s OK except that ice doesn’t like to pile up, The pressure liquifies the lowest layers so that it skates off downhill.
So far, the 300ft thick bank of sea ice floes has slowed up the collapse but now the sea is warming, the sea ice is disappearing and the glaciers are noticeably accelerating.
Antarctica iis also about 1/60th of the world’s surface area, so 60m of ice loss gives 1m of ocean rise. (use yards or fathoms if you like, same wet feet).
Ice is 1000s of metres (yards) thick on Antartctica, for the monent anyway.
