Rising Oceans

There is concern over the effects of global warming on the ocean level. (As an aside, How many oceans are there, anyway?) The ocean would be expected to rise because of the melting of the ice sheets on Antarctica, which cover one half of a percent of the Earth's surface and are, on average, 3 kilometers (1.8 miles) thick. The oceans cover 71% of the Earth's surface. If the ice caps melted completely, would we have to evacuate New York City?

Answer:

If they don't evacuate, they might wish to invest heavily in gondolas!

Calculation: Since the oceans cover 71 / .5 = 71 x 2 = 142 times as much area as the ice sheets, the ocean would rise by 1 / 142 of the thickness of the ice sheets. (Actually, since ice is less dense than liquid water, the amount would be somewhat less, but we will ignore that for the moment.) To get the thickness of the ice sheets in feet, we multiply 1.8 miles times 5,280 feet per mile, to find that the ice sheets are 9,504 feet thick. ****Dividing 9,504 by 142 gives us a rise in sea level of 66.9 feet. (Even if we adjust for the fact that ice is less dense than liquid water, the rise would still be at least 60 feet.) According to Wikipedia, the elevation of New York City is 33 feet. (A November 9, 2006 Christian Science Monitor article says that much of the city is below 10 feet.)

Oh yes, and as an aside, there is only one ocean. There is nothing that separates the Pacific from the Atlantic or the Indian from the Pacific -- it's all one big body of water.