Rising sea level is potentially one of the
most serious impacts of climatic change. Even
a small sea level rise would have serious
economic consequences because it would
cause extensive damage to the world's coastal
regions. Sea level can rise in the future
because the ocean surface can expand due to
warming and because polar ice sheets and
mountain glaciers can melt, increasing the
ocean's volume of water. Today, ice caps on
Antarctica and Greenland contain 91 and
8 percent of the world's ice, respectively.
The world's mountain glaciers together contain
only about 1 percent. Melting all this ice
would raise sea level about 80 meters.
Although this extreme scenario is not expected,
geologists know that sea level can rise
and fall rapidly due to changing volume of ice
on continents. For example, during the last
ice age, about 18,000 years ago, continental
ice sheets contained more than double the
modem volume of ice. As ice sheets melted,
sea level rose 2 to 3 meters per century, and
possibly faster during certain times. During
periods in which global climate was very
warm, polar ice was reduced and sea level
was higher than today.
