This Tiny Sphere is All the World's Water

By Veronique Greenwood | May 14, 2012 9:34 am


When you’re trudging through the pouring rain to the office, it seems like the Earth possesses an infinite amount of water, a not-insignificant amount of which is dripping down your collar. But when you see an image like this one, produced by the USGS, it hammers home the reality of the situation: the water’s all spread out in a very thin layer, like a millimeter of frosting on a cake. If you gathered all the world’s water—from oceans, lakes, groundwater, water vapor, everything—into a sphere, it would have a diameter of 860 miles. That’s the distance between Salt Lake City and Topeka, Kansas.

That’s still a fairly big sphere, when you think about it: that same water spread out in an even layer across the United States would leave us under a 90-mile-deep lake. But it isn’t nearly as big as you might expect, looking at our blue marble in photos from space or dipping your toes in the Atlantic. To boot, very little of that water—less than 4%—is freshwater, and the vast majority of that is locked up in glaciers and ice caps. We’ve got just a tiny fraction of that sphere at our disposal; it behooves us to use it wisely.

Read more at the USGS.

  • ceramicfundamentalist

    does this sphere also include all the water in hydrated minerals? i imagine that’s a pretty significant amount of water.

  • Red the Fister

    now my question: does that little sphere contain all the water found within the plants, animals and fungi?
    …i think i’ll go read more!

  • Red the Fister

    [edit] yes, the USGS article does, indeed, include the water within us in that sphere… if you’re wondering why i wondered, it’s simply because the picture shows the continents covered in greenery- where appropriate.
    It simply looks like the artist left out the plant life.
    …would we have recognized the continents for what they are if the greenery hadn’t been included?

  • Thomas T

    I ran the numbers based upon your map but I used 700 miles, Just to give you a break. I came up with a volume of water base3d upon V = 4/3 pr3 formula for a sphere of 140 MILLION MILES of water.

    the average sea depth is about 2 miles when you account for continental shelves and underground mountain ranges This seems consistent. While the surface of the Earth is large with 1.4 billion miles of water it goes a long way. After all we are not a planet of water but of rock and iron and nickel mostly.

    I simpler graphic would show likewise shocking pictures of oxygen and other important components of life.

    But using your own number of the sphere I come up with a volume of a sphere of 340 MILLION MILES of water.

    Stop using your position to scare people and use the truth.

    Has this amount varied over time? Has it gone up or down? Is it something odd?

    No this is about how much water we have had for millions and millions of years.

  • metis

    That’s a lot of cramped up fish….

  • Ralph C

    @ Thomas T. you stated some odd measurements in your calculations. or better I should say your units of measure. Volume of water is expressed in cubic miles water, and you simply state 140 million miles of water.

    then you state “…the surface of the Earth is large with 1.4 billion miles of water it goes a long way.” 140 million is smaller by a factor of 10 than 1.4 billion. It becomes even more significant when you are talking about cubic miles of water as opposed to linear miles of water.

    Then you state “a volume of a sphere of 340 MILLION MILES of water.”

    I am not arguing that your closing statements are incorrect: “Has it gone up or down? Is it something odd?” I would state that the original author Veronique makes it clear that only 4% of the total water at the current time is freshwater and accessible for plants and animals to survive. What if that 4% became completely tainted as to make the Earth uninhabitable? That I would think is the message of the original author.

  • Zolbar, Master of the Obvious

    @4: if your volume has units of distance, you need to redo your calculation. Also, what are you even talking about?

  • Old Geezer

    If it will put your mind at ease Thomas, I was not the least bit scared.

  • Brian

    Now they need to show the worlds oil and liquified gas next to it…

  • Wil

    If the diagram shows (~2 miles average depth x ~75% of the Earth’s surface) worth of water, I wonder what a similar diagram of the Earth’s crust would look like?

    I think the Earth’s crust has ~50 mile average thickness, and I read that the Earth’s crust, to scale, is thinner than an egg shell is to an egg.

  • Mike

    Thomas T, your math is off. For starters, volume is cubed (power 3), miles are linear (power 1). A “mile of water” is as nonsensical as trying to caluculate how many inches (instead of cubic inches) are in a gallon.

    Per wikipedia, there are 3.26 x 10^10 gallons of water and 261 cubic inches per gallon

    volume = 4/3 * pi * r^3
    radius in inches = (4/3 * pi * 261 cubic inches * n gallons)^(1/3) where n is 3.26 x 10^20

    The radius of the sphere of water would be 7.09 x 10^7 inches, or 5.91 x 10^6 feet of water or 1,119 miles (5,280 feet per mile). Diameter is 2 x radius, or 2,238 miles. I agree the sphere in the picture seems too small, but 140 million miles is a tremendous number.

  • stargene

    This picture and the data at the U.S.G.S site is a good, necessary
    illustration of the finiteness of things of this earth. The earth is
    huge. But it is finite. It’s treasure of water is huge. But it is finite.
    Looking at the relatively far smaller sphere of water, one can
    better understand how easy it would be for a massive, industrially
    complex and rather blind world civilization to misuse and wound
    this planetary gift.

    Our planet can take quite a beating, but not indefinitely… not
    forever. Pretending that it can.. won’t make it true. Pretending
    that scientists always exaggerate, for (pause…) “more grants”,
    won’t make it true. Trusting that big business and its political
    devotees hold our best interests at heart and that we shouldn’t
    worry our pretty little heads about ‘big stuff’ won’t make it true.

  • floodmouse

    So, what’s going on with that handwashing protocol that nurses and paranoid people use in my office building? They wash their hands, then let the water keeping running in the empty basin for 2-3 minutes while they dry thoroughly with a big wad of paper towels, then they deign to turn off the water with a paper towel so they won’t re-cootify their hands. I don’t like cooties either, but it would save millions of gallons of clean water if they’d do their paper-towel-turning-off-the-tap trick BEFORE they dry their hands, instead of after.

  • Richard

    I’m sorry,this calculation absolutely wrong.However I do believe water will be more valuable the gold nowadays.

  • James Hayes-Bohanan

    Thanks for this excellent visualization. It gives me an idea for a similar visualization we can do with our EarthView program (a giant globe we take to schools). I think we can make a “marble” representing just the fresh, liquid water.

    As stargene explains above at #12, this is not so much about scaring people as about helping people to understand how we could be concerned about the limits of a resource that seems so abundant. The fresh, frozen water, by the way, is tantalizing, since it seems likely we could use it as the climate warms. But as we know, most of what is melting is shifting toward the salty part.

  • Jerrold Bernstein

    Where I come from-nurses and docs shut the water immediately with their elbows!

  • jaykimball

    For those that are wondering what size sphere would be required to hold the fresh water accessible to humans, I updated the USGA image and posted it here:

    Jay Kimball
    8020 Vision

  • Willem56

    Will there be ‘less’ water?
    Does the world loose water?
    Do we need more water?

    As long as the sun shines the water will evaporate and rain down again.
    And with global warming more will evaporate and rain down… I call this natural cooling..:-)
    Limitless supply of rain that I can assure you…
    The challenge is to keep it free from toxins and pollutants.

  • justme

    You missed a spot yourself there. The equation should read

    radius in inches =( (261 cubic inches * n gallons)/(4/3 * pi))^(1/3) where n is 3.26 x 10^20

    Which gives a radius of just about 430 miles or a diameter of 860, as the article says.

  • Barry Johnstone.

    Combine that with religion, capitalism and politics and there is B I G trouble brewing!

  • Scott Baldwin

    The amount of water on the planet is the same now as it has been for millions of years. Where could it possibly go? It just moves around and takes multiple forms. We minuscule humans just have to keep coming up with ways to move it to where we need it. It’s a bit arrogant to think we humans could possibly “use it up”.

  • juan

    If we make the same calculation on CO2 we will obtain a much more scary result. All life on earth not only depends on water and sun’s light. Also on CO2, although some people consider it as a “venom gas”.

  • Carlos

    I’d like to instead see the following spheres volume/size compared to one another:

    hydrosphere (water),
    gaseous atmosphere,
    hardened planetary crust,
    all human tissue mass,
    all insect tissue mass,
    all other animal tissue mass,
    all plant tissue mass,
    all estimated petroleum and other hydrocarbon fuels.

    This would make more sense to see instead, as compared to overall planetary sphere mass. It would better illustrate the makeup of codependent relationships based on actual volumes of resources versus users.

    Forget about the planet size as a whole, one very large icy asteroid/comet impact could change all this. It could drown us land dwellers to the joy of future marine organisms after everything settles down in a couple of hundred thousand years if not much sooner.

    Am I scared, naw!

    The good ol’ sun will take care of the rest as it begins its red giant stage in about 500 million to 1.5 billion years from now. So bring bottled water, hamburger patties and sunscreen to that party!


  • Andii

    This seems retarded information to me.

    We drink it, we pee it, it goes back into the earth and replenishes with minerals and starts all over again.

    We die and it goes back into the earth.

    Water that we drink now is recycled and filtered through clouds and ground for millions of years. It’s not like we ship it off the planet. Were there a way to measure it, I would be you that pound for pound, we have just as much water now as we did a million years ago.
    Where the he11 is it gonna go people?
    The green movement is fake.
    Global warming is a scam.
    POWER TO THE SHEEPLE (sheelple = anyone that believes in the crap in this article)

  • Adrian Morgan

    When I first read this story (on another site), I immediately searched for alternatives to the oft-repeated “distance between Salt Lake City and Topeka, Kansas” analogy. The comment in which I listed these alternatives recieved a gratifying number of Likes, presumably from Europeans and Australians.

    For Europeans, Paris to Warsaw is 852.7 mi / 1372 km. For Australians, Melbourne to Brisbane is 853.3 mi / 1373 km. I can even improve slightly on the American estimate, offering Memphis to Miami (866.7 mi / 1395 km) as a shade better than Salt Lake City to Topeka, Kansas (869.7 mi / 1400 km). All distances via Wolfram Alpha.

    If you want to find your own, it’s easy to do with Google Maps open in one browser tab (for eyeball estimates to detect candidate city pairs) and Wolfram Alpha open in another (for precise distance calculations).

  • jaykimball


    On a finite planet, with a relatively closed system, it’s not so much that water disappears. Mostly the problem is that it gets polluted, or relocated. We want to make sure that we have clean safe potable water for drinking and farming, where we need it.

    But with 7 billion people consuming and polluting at an exponentially increasing rate, that is a challenge. There is less and less clean safe potable water each year, and much of the potential sources are drying up – e.g. snowpack, lakes, aquifers. Mostly that water is going to the sea. And though sea water is plentiful, it takes massive energy to desalinate. And it takes energy to transport the water inland. Wouldn’t it be easier if we just consumed more appropriately to the conditions at hand. Take Palm Springs for example. It’s a desert, and to waste a 18 million gallons a day keeping the golf courses green is not rational. They should at least be using gray water. For more on this, see:

    Human demand for fresh water is impacting the traditional water sources. As is climate change. The aquifers and lakes are being drawn down faster than replenishment. The snowpack is melting.

    By 2025, 1.8 billion
 people will live in conditions of absolute 
water scarcity, and 65 percent of the worlds population will be water stressed.

    These are good things to be thinking about now, because it will take a lot of time and money to adapt to these enormous changes. Not in a panicked fearful way, but in a rational informed way. As StarGene points out above, it’s a finite planet, and we want to make sure we understand the limits and conduct our selves accordingly.

    Jay Kimball
    8020 Vision

  • Oldskool

    I have no idea how you’d measure it, but, it looks much too small to account for all the solid and liquid water on the Earth.

  • DG Lewis

    The problem with this graphic is that it contrasts the volume of water with the total volume of the earth – when the overwhelming majority of the earth’s volume is totally inaccessible to people. The fact that there are literally hundreds of billions of rock and magma within the earth is kind of irrelevant to the discussion of how much water there is. The water’s “all spread out in a very thin layer” – but so is EVERYTHING ELSE ON EARTH that humanity is able to make use of.

    The average ocean depth is about 4km. The deepest mine is about 4km. If you assume that this depth is what is accessible to people, and multiply it by the surface area of the earth, you get a total accessible volume of about 2×10^9 cubic km. Of that, 1.4×10^9 is water. Yes, about 70% – have we heard that number somewhere before?


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