Please explain why melting icebergs willraise sea levels. When ice melts in a glass, it doesn't affect the level of water in a glass.

 Hilary Langston, Broomfield, Colorado

 MELTING ICE is an important cause of sea level rise, but not all melting ice contributes to sea level. The analogy of ice floating in a glas s is a good one forfloating sea ice. The height of the water in the oceans, a s in t h e glass, does not change much whether the water is in solid or liquid form. The melting ice from\ glaciers that contributes to sea level rise does not float but rather r ests on land. This situation i s analogous to setting a large ice cube on the rim of a glass; as it melts into the glass, the water rises.

 Patrick Megonigal, associate director for research,

Smithsonian Environmental Research Center