Antarctic Ice Melt Will Raise Sea Levels, Swamp Cities

Updated from 11:06 a.m. Tuesday with informtion on Norfolk's naval base on page 2.

NEW YORK (TheStreet) -- It won't be a world-ending flood. It will be a slow centuries-long creep of watery hardship, resulting in  redrawn maps of the world's coastlines and coastal economies looking very different from the ones we know.

That is the mechanism mankind -- ever its own worst enemy -- has helped set in motion.

According to the Environmental Protection Agency, citing scientific research, global sea levels have been rising throughout the 20th century and into the 21st, averaging a rise of 0.11 to 0.13 inches a year over the past 20 years. That is roughly twice the rate of the 100 years prior and translates into about a foot per century if that rate were to continue.

But two independent groups of scientists now are telling us that that rate will not continue. Instead, the rise of sea levels, caused in part by melting ice, will accelerate, resulting in a rise of 10 feet or more possibly within two centuries. And there's nothing we can do about it.

The teams of researchers released findings Monday indicating the West Antarctic ice sheet is melting, and that the melting is accelerating and unstoppable, setting off a chain reaction of surrounding ice melts.

According to a NASA press release, a joint study conducted between NASA and scientists at the University of California, Irvine, drew on 40 years of observations, including satellite images using radar interferometry. Interferometry uses satellite radar to precisely measure the ice sheet's vertical movement and determine with millimeter precision the line of contact with the ground beneath.  

Coincidentally, a second group of scientists from the University of Washington conducted an independent analysis using different means and came to similar conclusions. The two groups decided to release their results on the same day.

At root is warmer water stirred by stronger Antarctic winds, both fed by a warming of the planet caused in part by manmade greenhouse gases. The glacier ice extends from the land into shallower water and beyond, with part of the glacier floating on water. As warmer water melts the underside, the ice sheet thins and the part that is in contact with the shallow sea floor retreats.

Researchers have now determined the extent of that unseen melting, precisely identifying the retreat of the ground line -- the border between grounded and floating glacier ice. The conclusion is that the melting is happening faster than anticipated and is likely to continue, even if the warming of the water were to suddenly stop.

Surrounding glaciers are protected in part by this sea level ice sheet and will give way on their own in response to the weakness of their neighbor. The six immediate-vicinity glaciers together will likely raise global sea levels by 4 feet, while the risk is for even further melting that could ultimately raise global sea levels by 10 feet.

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But even that estimate could be understated as it does not take into account simultaneous melting that is occurring elsewhere -- in Greenland for instance.

None of this is a new idea. In 1978, researcher J.H. Mercer of the Institute of Polar Studies published his findings and theory that increased carbon dioxide emissions could cause enough of a rise in surface temperatures that it would threaten the delicate West Antarctic ice sheet. The summary of his findings, published in Nature in January of that year:

If the global consumption of fossil fuels continues to grow at its present rate, atmospheric CO2 content will double in about 50 years. Climatic models suggest that the resultant greenhouse warming effect will be greatly magnified in high latitudes. The computed temperature rise at lat 80 [degrees] S could start rapid deglaciation of West Antarctica, leading to a 5 m rise in sea level.

Reading that paper, it is clear that Mercer understood precisely the mechanism by which the West Antarctic ice sheet would destabilize. His work laid the groundwork for that done by the current generation of scientists, who now, 36 years later, have proven the validity of his projections.

A 10-foot rise in sea levels means South Florida will be swamped; Key West, Miami Beach and parts of Fort Myers will be mostly underwater, their buildings and infrastructure abandoned, growing mold and in ruins. In New York, JFK Airport would be flooded, Battery Park under water, riverside property on both sides of Manhattan will need to be demolished. Forget what you've seen in sci-fi movies: in our time, you can't live on the 10th floor of a building if the foundation is under water.

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