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Flash! Flooding?
Question by Ethan Gelber

The Question:

The North Pole has melted! It hasn't happened in 50 million years. More than just a few people are alarmed. But just how alarmed should we be? After all, minute changes in the earth's climate can dramatically affect things like the sea level, which can, in turn, dramatically affect how comfortable life is for evry human being. Think about it: 20,000 years ago, when the most recent ice age had tied up huge quantities of water as ice sheets and glaciers, the oceans were 330 feet lower than they are today.

And now the ice of the Arctic is melting? Of course, the real threat would come if the ice of the Antarctic started to melt as well. Then we might really be in trouble.

Just how much ice is believed to make up the southern polar ice cap that covers Antarctica? If it were to melt, by how many feet is it believed that the world's oceans would rise? Approximately how many people would be forced to relocate from submerged areas?

The Answer:

A response far more complete than anything I could have written came to us from Meredith Bailey. I will quote her in full here:

"About 98 percent of the continent of Antarctica is covered with ice, in some places as thick as two miles. The average thickness is roughly 1.5 km. The Antarctic ice is estimated to have a volume of 25 million cubic kilometers. This is 90 percent of the world's ice, and three-quarters of it is fresh water.

"There is more to the question of "How much would the oceans rise?" than meets the eye. The weight of the Antarctic ice cap is enough to actually depress the crust of the earth's surface, lowering the land to below sea level. If that ice were to melt, the crust would spring back into place. These two forces together would cause the oceans to rise an estimated 50 to 60 meters, or roughly (on average), 170 to 200 feet. (I'm going to ignore stuff like tides or the fact that "sea level" around the world is not constant — the rotation of the earth causes the Pacific and Atlantic Oceans to be at two different levels.)

"In general, scientists don't place a whole lot of stock in the notion that the entire ice cap will melt, however, since the Antarctic ice cap seems to currently be in equilibrium. Some do, on the other hand, estimate that global warming will cause the breaking off of several icebergs from the Antarctic ice shelves, raising the level of the oceans three feet or a meter over the next century. This three-foot rise alone would displace over 100 million people world-wide. A 5000 precent to 7000 percent increase in ice melted (that is, all the ice) would cause a significantly higher amount of displacement — and panic — among humans: probably in the range of billions of people. [Ethan's note: it is estimated that 3 billion people would be displaced by a 200-foot rise in the level of the oceans.]

"Over the short term run — that is, the next few decades — meteorologists think that the ocean levels will actually decrease by about two millimeters a year. This is because warm air (heated by global warming) has the capacity to hold more water than cold air; warmer air currents will evaporate more moisture over bodies of water, leading to more rain and snow storms, as well as other climate changes, the threat of which is probably much more real than the entire melting of the polar ice caps."

The Winners:

Our winners this week are: Steve Yates, Tyler Yates, and Meredith Bailey.

THANKS for your contributions!