Yep, the Earth is doing a balancing act with its water! Water is continually moving around,
Water is continually moving around, through,and above the Earth as water vapor, liquid water,and ice. In fact, water is continually changing itsform. The Earth is pretty much a "closed system,"like a terrarium. That means that the Earthneither, as a whole, gains nor loses much matter,including water. Although some matter, such asmeteors from outer space, are captured by Earth,very little of Earths substances escape into outerspace. This is certainly true about water. Thismeans that the same water that existed on Earthmillions of years ago is still here.
Thanks to the water cycle (view a graphic ofthe water cycle), the same water is continuallybeing recycled all around the globe. It isentirely possible that the water you drank forlunch was once used by Mama Allosaurus togive her baby a bath. By the way, there is a theory that much ofEarths water came from comets hitting theplanet over billions of years.
Where is Earths water located and in what formsdoes it exist? You can see how water isdistributed by viewing these bar charts. The left-side bar shows where the water on Earth exists;about 97 percent of all water is in the oceans.The middle bar shows the distribution of thatthree percent of all Earths water that isfreshwater. The majority, about 69 percent, islocked up in glaciers and icecaps, mainly inGreenland and Antarctica. You might besurprised that of the remaining freshwater,almost all of it is below your feet, as groundwater.
No matter where on Earth you are standing,chances are that, at some depth, the groundbelow you is saturated with water. Of all thefreshwater on Earth, only about 0.3 percent iscontained in rivers and lakes—yet rivers andlakes are not only the water we are mostfamiliar with, it is also where most of thewater we use in our everyday lives exists.
In the pie charts above, the top pie chart shows thatover 99 percent of all water (oceans, seas, ice, mostsaline water, and atmospheric water) is not availablefor our uses. And even of the remaining fraction ofone percent (the small brown slice in the top piechart), much of that is out of reach. Considering thatmost of the water we use in everyday life comes fromrivers (the small dark blue slice in the bottom piechart), youll see we generally only make use of a tinyportion of the available water supplies. The bottompie shows that the vast majority of the fresh wateravailable for our uses is stored in the ground (thelarge grey slice in the second pie chart).
For a detailed explanation of where Earths wateris, look at the data table below. Notice how of theworlds total water supply of about 332.5 millioncubic miles (about 1,385 million cubickilometers) of water, over 96 percent is saline.And, of the total freshwater, over 68 percent islocked up in ice and glaciers. Another 30 percentof freshwater is in the ground. Thus, rivers andlakes that supply fresh surface water for humanuses only constitute about 22,300 cubic miles(93,100 cubic kilometers), which is about 0.007percent of total water, yet rivers are the source ofmost of the water people use.
One estimate of global water distribution Water source Water volume, in cubic miles Water volume, in cubic kilometers Percent of freshwater Percent of total water Oceans, Seas, & Bays 321,000,000 1,338,000,000 -- 96.5 Ice caps, Glaciers, & Permanent Snow 5,773,000 24,064,000 68.6 1.74
Water One estimate of global water distribution Water Water Water volume, in Percent of Percent source volume, in cubic kilometers freshwater of cubic miles total waterOceans, 321,000,000 1,338,000,000 -- 96.5Seas, &BaysIce caps, 5,773,000 24,064,000 68.6 1.74Glaciers, &PermanentSnow