|MadSci Network: Earth Sciences|
Based on global tide gages, over the last hundred years sea level has risen by 10 to 25 cm. The contribution to the rise due to thermal expansion is estimated to be in the range of 2 to 7 cm. So the diameter of the earth is getting larger by a small amount.
The 10 to 25 cm change is dwarfed by the 120+ m change in sea level since the last ice age. If all of the ice in Greenland and Antarctica were to melt, sea level would rise about 70 m. Recent movies to the contrary, this can not happen quickly.
The future rate of sea level rise is questionable. So much of the coastal land is so flat and densely populated that a modest change in sea level can have significant local effects.
It is not expected, given the change since the last ice age, that either earthquake frequency or volcano eruptions will be affected.
Several web sites that may be of interest are:
Climate Change 2001: The Scientific Basis
Sea level rise from Wikipedia.
Warming to Cause Catastrophic Rise in Sea Level? and Global Warming Unstoppable for 100 Years, Study Says from National Geographic.David
Try the links in the MadSci Library for more information on Earth Sciences.