How Scarce is Earth's Fresh Water?

About 70% of the Earth is covered with water, equalling some 1,400,000,000 km3. 97.2% of the Earth's water is saltwater, leaving only 2.8% as freshwater: 0.022% is on the surface, 0.397% is in underground aquifers and wells, 0.001% is in the air and soil with 2/3 of the Earth's supply of freshwater locked in the polar ice caps and glaciers. So, 99.7% of all the water on Earth is unusable, being in the oceans, seas, atmosphere, or frozen in the ice caps and glaciers. That leaves 0.3% usable water, most of which is groundwater and out of our reach. The water we do use comes largely from our rivers and freshwater lakes, which represent a small portion of the Earth's freshwater sources.
http://water.usgs.gov/index.html

With such a small percentage of available freshwater, you would think that we would take care of it. The little water we have for our use is being polluted by the waste we create, most notably our sewage and the synthetic fertilizers and pesticides we douse our agricultural land and crops in. Add in the toxins, medications and pathogens from hospitals, or prescription medications that get dumped down toilets or sinks. Let's not forget about the petroleum, radioactive substances and all the other toxins that are dumped or get spilled in transportation.

Instead, much of our drinking water has to be heavily treated in order to make it safe for consumption again. We spend a lot of time and money to treat the sewage produced from sinks, toilets, and industrial processes and then put that treated water back into circulation. The quality of our water is declining in most regions, which not only affects us, but affects the diversity of our freshwater species and ecosystems. Estimates suggest that nearly 1.5 billion of the world's population does not have access to safe drinking water and many places are losing 30-40% of their water. But is our drinking water as safe as we think it is? These days, there is scarce any water that is safe to drink straight. Most of the water coming through our taps has been heavily treated to render polluted water "safe" again. This water often contains a lot of chlorine.

And what about those ice caps and glaciers? The ice cap on Greenland is moving toward the sea at a faster rate, with larger chunks of ice breaking off from the land to fall into the sea. Greenland's ice cap – which covers more than 650,000 square miles and stands up to 2 miles thick in places - is melting and moving at a much faster rate than previously estimated. In fact, Greenland's ice cap is moving toward the sea and melting at an exponential rate. The sea level is already rising with expansion brought on by higher temperatures and Greenland contributes to 1/6 of the rise in sea level, its southern glaciers are among the fastest moving in the world, and they have increased their flow rate to about 8 miles per year. 1 cubic mile of water is about five times the amount of water Los Angeles uses in a year. In 1996, Greenland dumped 90 times more ice and melt water into the sea than Los Angeles consumed, losing 22 cubic miles of ice and the frozen island is estimated to lose more than twice that much in 2006. Greenland poses a more immediate threat to the sea level than does Antarctica, but the melt water from Greenland greases the way for massive outflows of ice, which could unleash a chain of events bearing greater consequences than the current rise in sea level.

Sections of ice the size of small states from the Arctic and Antarctic are disintegrating into hundreds of tiny pieces. Large portions of Antarctica are melting, or breaking off to fall into the Southern Sea. The ice shelf that is sitting on land and is about ten times the size of Greenland's ice cap. The main cause for alarm here is the Western Antarctic Ice Shelf (WAIS) - which is about the size of Greenland's ice cap - but not because it is melting. The main danger from WAIS is that the ice sheet is actually sitting in an oceanic basin of slippery mud. WAIS has been protected by a veritable ice river. This sheer mass of ice prevents WAIS from much movement and it slows erosion by blocking the ocean waves, providing a very important benefit to the stability of the shelf. But those ice flows around the shelf are rapidly diminishing, both melting and moving away at a faster rate than before, aided by the melt water from Greenland. What if the water of the ocean were to slip under break up the slippery mud supporting WAIS, sending the ice shelf in a free float?

Ice, as in the ice covering the North and South poles', bounces back 90% of the sunlight and energy that hits it whereas water absorbs 90%. As the ice shrinks back, there is more water surface, which means that more energy gets retained and it gets warmer. This, in turn, means that the ice melts and shrinks faster than previously, each mile vanishing faster than the last.

We don't need to worry so much about the melting of the already floating glaciers as they have already displaced all the water they are going to and aren't going to cause the sea level to rise any more than it already has. Remember that 2/3 of the Earth's freshwater is locked in the polar ice caps and glaciers. One estimate says that the Antarctic has enough ice to raise sea levels more than 215 feet. WAIS itself could raise the sea level by 10-20 feet. Greenland's ice cap would cause sea levels to rise by about 20 feet. Dumping Greenland's ice into the sea would swallow large parts of Florida and most of low-lying Bangladesh. What if all the ice currently on land were to melt or fall into the sea? A one foot rise in sea levels will cost us up to 100 feet of land, depending on the land's altitude. That is a lot of land, especially to a growing population with shrinking resources.