Science Questions

Sun, 5th Mar 2006

Part of the show Recycling, Water Use and Problem Plastic

Question

Jim in Ipswich asked:

We reckon that all the polar ice caps are melting. Assuming that they've all melted and the water levels have all risen, how much land would be left and would there be enough land for us to survive on?

Answer

If you wanted to define whether there would be enough land, you could give everyone a metre-squared of the Isle of Wight for the moment but that's not really survivable. In terms of the poles melting, people say it's really bad news if the poles melt, but it's not. If the North Pole disappeared tomorrow, there wouldn't be any change in sea level. The reason for that is that it's entirely made of ice and ice is floating. As you know, ice is made of water and weighs the same as water. The amount of water level change is proportional to displacement so if the North Pole melted we wouldn't be in much trouble. The real worry is ice on land, so that's Greenland and the South Pole. If that melts, we are in trouble. Predicted sea level rises for the next 100 to 200 years is anything from a few centimetres maybe to as much as seven metres over the next 700 years. But it's not just the melting of the water. If the planet warms up, things will start to expand. Just the getting warmer effect is enough to make the water expand a bit and to increase in depth. In fact, the melting of the ice on Greenland alone is contributing to about a 0.5 centimetre rise in ocean levels everywhere every year.

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