Basic Graph #4

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Although sea levels have been rising since the end of the last glaciation (nearly 11,000 years), the rate of rise has increased over the past 200 years as average global temperatures have increased. The rise is due to two factors, the freshwater being added to the oceans from ice melt in the cryosphere , and the thermal expansion of the oceans due to rises in sea temperature.

The contribution from Antarctica melt water is uncertain, and there is a distinct possibility of surprises from this southern region. The floating ice shelves, notably the Wordie and Larsen A and B shelves, broke up very rapidly during the 1990s, after rapid regional warming. Climate, like other complex systems do not always vary in a smooth fashion, and sudden changes can occur over wide areas. Critical levels, or thresholds may be reached in a system whereupon drastic, and perhaps disastrous results occur.

Threshold events in this case include the complete or partial shutdown of the ocean thermohaline circulatory system, disintegration and melting of Antarctica and Greenland Ice Sheets (the polar caps) , and major changes in the carbon cycle, due to biospheric effect."

The EPA website has more information on the causes and implications of sea level rise due to climate change.