The world's glaciers react to and interact
with changes in global and regional climates.
Most mountain glaciers worldwide have been
retreating since the latter part of the 19th
century; global sea level has risen about 10
centimeters during the past century. Glaciers
vary in size as a result of several factors, of
which climate variation is probably the most
important. The reasons we are interested in
glacier variation include its connection to climate
change and to global sea level.