All the Water on Planet Earth

Explanation: How much of planet Earth is made of water? Very little, actually. Although oceans of water cover about 70 percent of Earth’s surface, these oceans are shallow compared to the Earth’s radius. The above illustration shows what would happen is all of the water on or near the surface of the Earth were bunched up into a ball. The radius of this ball would be only about 700 kilometers, less than half the radius of the Earth’s Moon but slightly larger than Saturn's moon Rhea which, like many moons in our outer Solar System, is mostly water ice. How even this much water came to be on the Earth and whether any significant amount is trapped far beneath Earth's surface remain topics of research.

Illustration Credit & Copyright: Jack Cook, Woods Hole Oceanographic Institution, Howard Perlman, USGS

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Replies to This Discussion

It would be nice if another diagram showed how much water is potable.

Perhaps the fresh water ball would be too small to show up at that scale.

Indeed you are correct. Eventually, probably not to long from now desalination will be required to supply the water needs of humans and crops.

I'd read that the snow pack was high this Winter, but then read about severe drought in the West. This was confusing until I learned that

...last winter's snowpack was relatively high. But the spring runoff never came, because the snow evaporated straight into the air of the hottest spring on record. [emphasis mine]

As Farms Bite the Dust, "Megadrought" May Be the New Normal in the ...

So even as the water cycle increases 4%, and we get more rain and snow, we also get more drought. Climate Destabilization isn't fair! I knew that some rain would evaporate before it hit the ground, but didn't imagine an entire snow pack sublimating.

Apparently ice gets this appearance after sublimating for several days.

I found your article quite compelling. One comment:

" the last century's human population growth in the American Southwest occurred during a relatively wet period in the climactic record. We were due for another megadrought sooner or later which could be expected to dramatically alter human settlement patterns in the area. While this current heat may not be caused by global warming, climate change could nonetheless trigger the next megadrought."

William deBuys, A Great Aridness.

If ever warming water becomes toxic due to cyanobacteria, human health and wildlife suffer. Spain already has a problem with toxic cyanobacteria contaminating reservoirs upon which the public depends.

Global Warming Favors Proliferation of Toxic Cyanobacteria

"Cyanobacteria love warm water, therefore an increase in temperature during this century may stimulate their growth, especially that of the cytotoxic varieties, which could even produce more toxins and become more harmful,"...

"These toxins may affect the liver and other organs (hepatotoxins), the nervous system (neurotoxins), different cells (cytotoxins), the eyes and mucous membranes, as well as causing dermatitis and allergies,"...

approximately 20% of Spanish reservoirs (278 were sampled) revealed cyanobacteria in concentrations of more than 2 mm3/l, the guide level established by the WHO for bathing water quality.

In the group exceeding the limits, in 45% of the cases concentrations of microcystins (toxins which particularly affect the liver) were found at above 1 microg/L, which is the value recommended by the WHO and the maximum level established by Spanish legislation for bathing water.[emphasis mine]



One of our nearby beautiful lakes, Spirit Lake, Idaho, with Cyanobacteria bloom,

Spirit Lake, Idaho

Canada has widespread toxic cyanobateria contamination of freshwater lakes too.

Potent Human Toxins Prevalent in Canada's Freshwaters

A new paper just published in the Canadian Journal of Fisheries and Aquatic Sciences shows that microcystin, a toxin produced by cyanobacteria, is present in Canadian lakes in every province.

"Canadians enjoying their summer at the cottage need to know that those green scums of algae washing up on their beach are not only unsightly, but can also be a threat to their health and their children's health,"...

"Blue-green algae present a growing health concern for domestic, agricultural and recreational water use in Canada and world-wide," warns Dr. David Kinniburgh, the Director of the Alberta Centre for Toxicology at the University of Calgary. "The microcystin toxins they produce can cause acute liver failure in humans and may even cause cancer with long-term exposure." [emphasis mine]

A slideshow on toxic algae in the US.

Stay Out of the Water: Toxic Algae

This is Lake Erie in Oct 2011.

The bright green is a cyanobacteria bloom. According to In summer, toxic blue-green algae blooms plague freshwater from the Food and Environmental Reporting Network, industrial agriculture and climate change are fueling massive blooms of toxic algae.

The report noted that no federal agency tracks the occurrence of freshwater algal blooms, but experts say they're getting worse, driven by fertilizer and manure running off farm fields and into lakes and streams. Earth's warming climate multiplies the effects. 

Increasing Pollution, Dwindling Options

Showing how easily algae can take over, one of the Olympic pools turned green over night.

A perfect example of why algae are showing up in water everywhere in greater numbers. It does not take much to reach a nutrient threshold and then some extra heat finishes the job. Both of these pools were blue the day before. Maria Lenk Aquatics Centre on Day 4 of the Rio 2016 Olympic Games on August 9, 2016 in Rio de Janeiro, Brazil.

Greg in Robert Scribbler comments Aug 11th

Great article link Ruth!




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