What happens if the polar ice caps melt?

9.a What happens if the polar ice caps melt?

­There has been much discussion about the possibility that global warming will cause the polar ice caps to melt and flood many coastal cities. Most scientists believe that this process would take thousands of years, if at all.

Most of the world's ice (90%) is in Antarctica. The average temperature in Antarctica is minus-35Fahrenheit (minus-37° Celsius) — well below the temperature at which water freezes — so any significant melting of the Antarctic ice cap is considered very unlikely to happen.

It is considered possible that only a portion of the ice will melt, even over a long period of time, and that sea levels will increase by no more than a few feet.  If the polar ice caps melted enough to cause the ocean levels to rise several feet, the results would be significant. The streets of many current coastal cities (like NYC) would be underwater, necessitating their evacuation. Low-lying countries, such as many of those in Indonesia, could become almost entirely submerged. The new standing water would be ideal for the breeding of mosquitos and other insects, spreading diseases such as malaria. Flooding also could cover much farmland and affect the world's food supply. Farmers in the flooded areas would need to move to more elevated land, which might be less suited to growing crops.

What is not possible is that all the world's land would be covered if the polar ice caps melted. There simply is not enough ice on Earth for this to happen. Even in a severe flood, only a small percentage of the world's land would be lost.

 9b. What other questions do you have about the Science Inquiry Experience?

So what will happen in the future? No one really knows for sure. In 1995, the International Panel on Climate Change asked scientists to make some predictions. They predicted how sea level might change by the year 2100. The lowest predictions were at six inches and the highest at 37 inches. The rise will come from thermal expansion of the ocean and from melting glaciers and ice sheets. Let’s say it’s somewhere in the middle of the predictions, say 20 inches. That’s no small amount-- it could have a big effect on coastal cities, especially during storms.