Saturday, June 7, 2008

Global Warming Part 2. What's wrong with more summer?

Coming out of a harsher than average New Hampshire winter, I see little wrong with shorter winter and earlier summer. We had a three inch snowstorm on the last day of April, and had to wait until today for the first truly warm day of the year. A couple of degrees of global warming would only drive the last snow back into March and move the onset of warm weather back into mid May. That ain't a catastrophe. We get a longer growing season, we still have winter skiing.
What's so bad about that?
Historical records show the Medieval Warm Period as a climatic optimum for Europe. Good harvests, good population growth, a good time. The Little Ice Age that set in for the 15th century was a disaster. With help from the Black Death, it cut the population of Europe in half.
If the Arctic ice went out it would improve the climate in all the Arctic lands, changing them from frozen wastelands into habitable farmlands. Since ice floats mostly underwater, like 90 % of an iceberg is submerged, melting the arctic ocean ice won't do much to raise sea level.
To get real sea level rises we have to melt the Antarctic ice cap. Greenland is only 15% the size of Antarctica and much of the Greenland ice cap is already below sea level. For a back of the envelope calculation we can ignore Greenland, it's Antarctica that counts. A crude calculation based on the relative area of the world oceans and the Antarctic is scary, melting the Antarctic ice cap might raise world sea level by 200 feet. Antarctica on the other hand is on land, so the ocean currents cannot melt it the way they can the Arctic. Antarctica is really, really cold. The average temperature is -30 C. The Antarctic ice cap won't melt until global temperatures climb 30 degrees C (54 degrees F). The most extreme global warming predictions are calling for temperature rises in the single digits, that isn't enough to melt out the South Pole. Without melting Antarctica, sea level rises will be in the one or two foot range at worst.
Around here we get a nine foot tide. Seawalls, locks, beaches, beach front property is already coping with an ocean that goes up and down 9 feet. An extra foot or so at high tide isn't going to flood downtown Boston.
So, far as I can see, a few degrees of global warming will give us a nicer planet to live on.

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