Tuesday, May 5, 2020

Notes From All Over, Mid-Afternoon Edition -- May 5, 2020

Tesla:
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The Science Page

One of the most fascinating things I ever did in high school was dissect a frog. It turns out one can order an entire frog-dissecting kit over at Amazon.com for less than $15/set. I'm going to ask Sophia if she would be interested.

Meanwhile, earlier I wrote that we would be doing this scientific experiment, to look at global warming and rising seas:
  • put a bunch of ice cubes in a glass
  • fill the glass with water to the brim
  • come back in an hour and see if the water spilled over the brim of the glass
  • hint: water expands as it freezes; as the ice cube melts, the volume of water in the glass should actually decrease  
I got the idea after reading this article at Watts Up With That: first results from NASA's ICESat-2 mission map sixteen years of melting ice sheets. It's a great read, but be sure to read the social media comments to put the article in perspective.

It's not a particularly long article. Quite technical in nature.

The article is eighteen short paragraphs, but it is not until you get to the sixteenth paragraph that you read this (it is alluded to in an earlier paragraph):
Ice that melts from ice shelves doesn’t raise sea levels, since it’s already floating – just like an ice cube in a full cup of water doesn’t overflow the glass. But the ice shelves do provide stability for the glaciers and ice sheets behind them.
Hmmm. Watts Up With That?

Other observations:
  • sixteen years of satellite data vs eons of life on earth; plate tectonics; glaciation, etc. Sixteen years sounds kind of puny
  • sea rise of 14 millimeters noted over sixteen years; since 2003; about a millimeter rise per year
  • we have many numerators in the article but no denominators; examples of numerators:
    • Greenland lost an average of 200 gigatons of ice per year;
    • Antarctica lost an average of 118 gigatons of ice per year;
    • sea rise of 14 millimeters over sixteen years; 
    • one gigaton of ice is enough to fill 400,000 Olympic-sized swimming pools;
    • iceberg calving: two-thirds from Greenland; one-third from Antarctica;
    • the two largest Greenland glaciers have lost 14 to 20 feet of elevation per year
And then without much discussion:
In Antarctica, the dense tracks of ICESat-2 measurements showed that the ice sheet is getting thicker in parts of the continent’s interior, likely as a result of increased snowfall, Smith said. But the loss of ice from the continent’s margins, especially in West Antarctica and the Antarctic Peninsula, far outweighs any gains in the interior. In those places, the ocean is also likely to blame.
Number of Olympic-sized swimming pools in the earth's oceans:
  • 1.35 billion cubic kilometers
  • one cubic kilometer of water = 2.64 x 10^11 gallons
  • 1.35 billion cubic kilometers = 1.35 x 10^9 x 2.64 10^11  = 3.56 x 10^20 gallons of water (volume of ocean)
  • volume of Olympic-size swimming pool: 660,000 gallons or 6.6 x 10^5
  • dividing ocean volume by pool volume: 3.56 x 10^20 / 6.6 x 10^5 = 0.5 x 10^15 = 5 x 10^14
  • the ocean is equivalent to 5 x 10^14 Olympic-size swimming pools, or 500,000,000,000,000 pools
  • 4 x 10^5 / 5 x 10^14 = 0.0000000008 = 0.00000008%
Note: I often make simple arithmetic errors. If this important to you, do your own math.
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