>>I still don't see how the "Greenland Icesheet" numbers add up. The numbers are all available. I don't see how you can take the mass of ice covering 1/129th of the area of the oceans, and even if I granted you that the whole thing was 328 feet thick (instead of 328 feet thick at its thickest point)<<

Because that's wrong. You need to quote your sources. Here's mine:

also called Inland Ice , Danish Indlandsis single ice cap or glacier covering about 80 percent of the island of Greenland and the largest ice mass in the Northern Hemisphere, second only in size to the Antarctic ice mass. It extends 1,570 miles (2,530 km) north-south, has a maximum width of 680 miles (1,094 km) near its northern margin, and has an average thickness of about 5,000 feet (1,500 m).

http://www.britannica.com/eb/article-9037979/Greenland-Ice-Sheet

>>the most one could hope for in raising sea level would be 2.54 feet. (And before someone says "but 2.54 feet would be catastrophic in and of itself!" -- remember that the ice ISN'T 328 feet thick).<<

Right, it's 5000 ft thick. And that's AVERAGE thickness.

The Greenland ice sheet occupies about 82% of the surface of Greenland, and if melted would cause sea levels to rise by 7.2 metres[3]. Estimated changes in the mass of Greenland's ice sheet suggest it is melting at a rate of about 239 cubic kilometres (57.3 cubic miles) per year [1]. These measurements came from NASA's Gravity Recovery and Climate Experiment (GRACE) satellite, launched in 2002, as reported by BBC News, 11 August 2006.

http://en.wikipedia.org/wiki/Ice_sheet

I called it an ice cap but apparently an ice cap is under 20,000 sq. miles while an ice sheet is over 20,000. However, the Britannica link above does call it an ice cap so take your pick.

But, regardless, the danger is not the flooding--at least not yet--the more immediate danger is the Oceanic Conveyor Belt, which regulates earth's temperatures, is being disrupted and that can cause the planet to overheat and we know this is already happening. Quite frankly, I don't think anything can be done about it and that's pretty sad and scary.