Reader DB writes:
Let's do the math: 0.4 inch in 20 years is 2 inches per century; 2 inches is 0.167 feet per century; 200 feet would take 1,200 centuries, which would be only 120,000 years. No wonder Brian Williams is so worried.Antarctica, Greenland ice definitely melting into sea, and speeding up, experts warn - World News
And while a 0.4 inch rise in sea levels over 20 years doesn't sound like much, many experts fear further warming will accelerate the polar melt. The ice sheets would raise sea levels by more than 200 feet if they completely melted over centuries — not likely, but even a tenth of that would have catastrophic impacts on coastal areas.