Click on the map to explore the effects of changing sea level on the modern coastlines. The interactive maps will allow you to change sea level by fixed amounts, by known past change extremes or by observing the effects of melting the various large ice sheets.
Thermal Expansion:
As the ocean warms, the density decreases, so that even at
constant mass the volume of the ocean increases. The thermal
expansion of water accounts for a large portion of the change in sea
level and is dependent upon changes in atmospheric temperature.
Global warming has had the effect of increasing thermal expansion.
The vast amount of greenhouse gases, such as carbon dioxide and water
vapor, released into the atmosphere has led to a greater amount of
heat absorbed in the infrared. These gases then reradiate this energy
and direct some of it back toward the earth's surface, leading to
small increases in global temperature and an expansion of the ocean's
volume.
Over the course of the twentieth century, thermal expansion has contributed to sea level rise by .3 to .7 mm/yr. In the future, thermal expansion is expected to be the largest contributor to sea level rise over the next hundred years; it will lead to a .11 to .43 m rise.
Melting Glaciers and Ice Sheets:
A glacier, ice cap or ice sheet gains mass by accumulation of
snow transformed to ice and loses mass (ablation) by melting, runoff,
and evaporation. The melting of glaciers and polar icecaps, due to
warming temperatures, leads to a rise in sea level. Over the 20th
century, the melting of glaciers and ice caps has contributed about
.2 to .4 mm/yr to sea level. According to the IPCC, ice sheets will
continue to react to climate warming and contribute to sea level rise
for thousands of years even after current climate changes have been
stabilized. Sea level has been rising steadily, about 1-2 mm/year,
since the end of "Little Ice Age" in the 19th century. This has
resulted from the reduction in volume of ice caps, ice fields, and
mountain glaciers, in addition to thermal expansion. However if
current increases in global temperatures continue or accelerate due
to global warming, many of the world's mountain glaciers will
disappear.