Global sea level rise is caused by two factors. One is the delivery of water to the ocean as land ice melts, such as mountain glaciers and polar icecaps. Current evidence of global warming includes the widespread retreat of glaciers on 5 continents. For example:
* The ice cap on Mount Kilimanjaro may be gone in 20 years. About 1/3 of Kilimanjaro's ice field has disappeared in the last 12 years and 82% of it has vanished since it was first mapped in 1912.
* Sea ice in the Arctic Ocean is thinning.
* Massive Antarctic ice sheets have collapsed into the sea with alarming rapidity.
As water temperatures rise, oceans spread.
The 20th century has seen a dramatic rise in sea levels.
The second factor is the thermal expansion of water within the oceans. As the temperature of the waters in the oceans rises and the seas become less dense, they will spread, occupying more surface area on the planet. Increased temperature will accelerate the rate of sea level rise.
Since the end of the last ice age, 18,000 years ago, sea level has risen by over 120 meters.
* Geological data suggests that global average sea level may have risen at an average rate of 0.1 to 0.2 mm/yr over the last 3000 years.
* However, tide gauge data indicate that the global rate of sea level rise during the 20th century was 1 to 2 mm/yr.
Coastal U.S. has seen beach erosion and dying coastal plants. Along relatively flat coastlines, such as those of the Atlantic, or coastlines bordering fertile, highly populated river deltas, a 1 mm rise in sea level causes a shoreline retreat of about 1.5 meters. We are already seeing evidence of shoreline retreat in the U.S.:
* Along the marshy Gulf Coast of Florida, the effects of sea level rise can be observed in the number of dead cabbage palms at the seaward edge of the salt marsh.
* Along the Atlantic Coast of the USA, erosion is narrowing beaches and washing out vacation houses. As sea level rises and coastal communities continue to grow and pump water from aquifers, salt water intrusion into groundwater will become a greater problem.
Land of some island nations is being submerged under water. Low-lying Pacific island nations will be inundated or the rising sea level will invade their drinking water aquifers.
* Tuvalu comprises nine coral atolls between Australia and Hawaii. Their highest point is 5 meters (15 feet) above seal level. As sea level has risen, Tuvalu has experienced lowland flooding. Saltwater intrusion is adversely affecting drinking water and food production. Tuvalu's leaders predict that the nation will be submerged in 50 years. In March 2002, the country's prime minister appealed to Australia and New Zealand to provide homes for his people if his country is washed away, but the plight of this nation is being ignored.
* Other threatened island nations include the Cook Islands and the Marshall Islands. During the last decade, the island of Majuro (Marshall Islands) has lost up to 20 per cent of its beachfront.
The near future could see millions of "climate refugees." In addition to island nations, low-lying coastal countries are threatened by rising sea level. A 1 meter rise in sea level would inundate half of Bangladesh's rice land. Bangladeshis would be forced to migrate by the millions. Other rice growing lowlands which would be flooded include those of Viet Nam, China, India and Thailand. Millions of climate refugees could be created by sea level rise in the Philippines, Indonesia and Egypt.
Earth has been experiencing the 10 warmest years on record.
Current rate of fossil fuel consumption indicates that the carbon dioxide content of the air will double by 2100
