Dear Tom,
Does the ocean level rise when an iceberg floating in the water melts?
Jeff Melross

Dear Jeff,
The weight of water remains unchanged when it freezes into ice. You will still have the same weight of ice. That is to say, one pound of water will freeze into one pound of ice; similarly, one pound of ice will melt into one pound of water. Therefore, an iceberg weighing say 1,000 pounds will melt into exactly 1,000 pounds of water.

An iceberg floating in the ocean will not increase the level of the ocean when it melts. Water increases in volume by 9.05 percent when it freezes into ice. That is, ice has less density than water and that is why it floats. This is as true for an iceberg floating  in the ocean as it is for an ice cube floating in a glass of water.

The world’s oceans are rising because of two factors: The melting of snow and ice on land, and also because a warming climate is gradually warming the oceans as well. Water expands slightly as it warms.