Thursday, March 13, 2008

National Geographic: Naked Science: Glacier Meltdown

On Sunday, March 9, right after “Aftermath: Population Zero” (previous review), the National Geographic Channel broadcast “Naked Science: Glacier Meltdown.” The NG link is here.

This was one of the most compelling programs yet. The program discussed both Greenland (with about 500,000 cubic miles of ice) and Antarctica (with about 5,500,000 cubic miles). In 2001, there had been a prediction that global warming would cause sea levels to rise about 3 feet in the century. But 2003 even the predictions were getting more dire. Ice is sliding off of Greenland the way an ice cube slides on a surface once the surface is wet – kids try it in high school physics labs as a friction experiment. In Antarctica, ice shelves are splitting because of direct melting. The predictions rose to about a 20 foot rise, and then eventually to a possible 150 foot rise in sea levels by 2100 if worst case scenarios occurred. It used to be that the permanent ice in the Arctic would cover the area of the United States; now that area is reduce to that west of the Mississippi River.

Ice core analysis show that climate can indeed vary, but analysis presented in the film (very much as in Al Gore’s film “An Inconvenient Truth”) shows that human activity since the industrial revolution has certainly accelerated it. Another great danger is that as more ice shelf melts, the albedo of the Earth is reduced, and warming accelerates even more, since the Earth is darker. Maybe something like this happened to Venus a billion or so years ago. (By the way, some evidence suggests that Venus may have overheated relatively quickly and “recently”, maybe just a few hundred million years ago.)

The film predicted more north Atlantic hurricanes, and noted that northern hurricanes have relatively higher wind shear in the northeastern quadrant. A major hurricane in New York could put lower Manhattan under 25 feet of water, flooding Battery Park and maybe Wall Street. (I lived in the Village in the 70s, and that is at around 100 feet, I believe.) Part of the problem is the “right angle” of the harbor between New York City and New Jersey. Southern Long Island was devastated and lower Manhattan was flooded with a 1992 “noreaster” that wasn’t a hurricane.

If one looks at a 1950 World Book Encyclopedia state map for any coastal state, one can see the areas that are under 100 feet elevation (dark green; 100-500 feet is light green, and 500-1000 is yellow). Such a map shows that an appreciable part of the Tidewater Virginia and Maryland areas could be at great risk.

The movie did not discuss the possibility of sudden “cooling” of Europe if the melting glacier disrupted the Gulf Stream current.

The movie also notes that the orbit of the Earth has a 100,000 year natural cycle where it varies from circular to more elliptical (students in Algebra II get asked to compute eccentricities of ellipses on those dreaded algebra tests; this program might make the concept relevant to them).

Earlier films: History channel.

Anderson Cooper’s Planet in Peril.

Also, see a discussion of the DC Environmental Film Festival, here.

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