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Archive for Saturday, June 14, 2003

Rising sea levels threaten island nations, coastline cities

June 14, 2003

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The sea has captivated human minds for centuries. Ulysses played out his epic adventures on the background of its changing tides. Columbus crossed its turbulent waters to discover the new world. Giant squids, man-eating sharks and florescent fauna wander its expansive depths.

Tuvalu has built its life around the sea's blue waters. An island nation situated in the southwest pacific, Tuvalu sustained itself on the sea, with the Tuvalu Maritime School producing some of the mostsought-aftersailors. But the tides have turned, and the sea, once a rich resource, is threatening to overcome Tuvalu's nine island atolls.

Tuvalu stands tall with its highest point rising to five meters above sea level. According to the United Nations Framework Convention on Climate Change (UNFCC), mean sea level has already risen 10-20 cm over the past 100 years. Using the UNFCC's models, scientists predict sea levels could rise anywhere from 9 to 88 cm by 2100, leaving Tuvalu underwater.

Tuvalu's 11,000 citizens are well aware of the sea's impending threat. Many predict Tuvalu will meet its watery fate in less than 50 years, and Tuvalu's citizens have already started to abandon ship, applying to immigrate to its neighboring nations Australia and New Zealand.

Tuvalu is not the only island to suffer a similar fate. The Alliance of Small Island States (AOSIS) was formed in 1990 at the Second World Climate Conference. It is made up of 43 island nations all threatened by rising sea levels. The Maldives, for example, has a population of 320,165, with 644 km of coastline and an elevation high of 2.4 m. The Marshall Islands are also in danger with an elevation high of 10 m and 370 km of coastline. A simple one-meter sea level rise could send islands like these looking for higher ground.

According to the paper entitled The Impacts of Climate change on Pacific Island Countries, published by the Small Island Developing States Network, rising sea levels will cause island nations to lose their profitable beaches to coastal erosion. Salt water will invade the groundwater supply of island nations, affecting agricultural activities, tourism and the population's health. Rising sea levels will also disrupt valuable ecosystems such as mangrove forests, coral reefs and wetlands. What's more, UNFCC scientists predict that tropical storms could become more intense and frequent, increasing the threat to low-lying islands.

Bangladesh is not an island, but its 133 million people could be in great danger. Already tropical storms rip through the nation killing thousands. With higher sea levels, those storms could reach further inland, affecting more of the population.

The world has felt and will continue to feel the effects of rising seas. Venice, Italy, a popular tourist attraction and often dubbed a city of romance, has already documented the changing tides. Apartments once used at the turn of the century are now flooded, and every year floods pour into St. Marco's square, spreading the canals' sewage water throughout the city.

New Orleans, La., is a "city in a state of denial," said Bruce C. Douglas, senior research scientist at the Florida International Institute, who has 20 years of experience in sea level research. Parts of New Orleans are as much as five feet (1.5 m) below sea level. Imagine what a one-meter sea level rise could do to Bourbon Street.

Similarly, New York City is vulnerable to the encroaching sea. According to a study entitled The Risk of Sea Level Rise by James G. Titus of the U.S. Environmental Protection Agency (EPA), there is a 50% chance that sea levels could rise 55 cm in New York City by the year 2100. This could affect New York City's infrastructure, such as its underground subway system and pipelines.

Not just the Big Apple, but the world's sandy playgrounds are also at risk. Douglas estimates that beaches retreat at 100 times the rate of sea level rise. "If sea level rise is a foot you expect to lose 100 feet of beach." Most beaches are not more than a couple of hundred feet wide. Douglas' most recent study, Sea Level Rise and Coastal Erosion, examined historical records (property titles, surveys, etc.) of beach locations. Douglas found that 80% of the U.S. East Coast has experienced erosion.

Thus, rising sea levels are a global problem, but what is causing the sea to spill over its banks? That is subject to debate. Scientists for the UNFCC said, "Measurement records indicate an increase of 0.6_.0.2_C in global average temperature since the late 19th century." It predicts global temperature will rise by 1.4-5.8_C by the year 2100.

Most scientists agree that sea level rise has something to do with global warming and green house gases. "There is no doubt the planet has gotten warmer," said Douglas.

As the oceans warm, they expand. Douglas, a former rocket scientist, attributes about 1 mm of the annual 2 mm sea level rise to global warming and thermal expansion. He said another _ mm per year could be attributed to the melting of mountain glaciers.

However, the biggest potential contributors to sea level rise are the polar ice sheets. The Greenland ice sheets cover 84% of Greenland's total land area or 1.75 million square kilometers. Antarctica is virtually all ice, with 98% or 13.72 million square kilometers covered in ice. Just as placing an ice cube in a full glass of water would make the glass overflow, scientists estimate the melting of the Greenland ice sheets could cause a seven-meter sea level rise, while the Antarctic ice sheets could cause a 70-meter sea level rise.

Although scientists aren't predicting all of the polar ice sheets will melt, there is no doubt polar ice sheets could greatly affect sea level rise.

For that reason, KU Scientist Prasad Gogineni, principle investigator for the PRISM project, is studying the changes in polar ice sheets.

"What we don't know at this stage is whether those [changes] are really related to the global climate change," said Gogineni

The PRISM project, funded by the National Science Foundation and NASA, is one of a series of projects designed to document and predict changes in the ice sheets.

Gogineni and his team will begin their first field tests on the Greenland ice sheet in June. Using a new imaging system based on SAR (synthetic aperture radar), the team will attempt to create an accurate image of the surface of the bedrock beneath the ice. With this information, scientists will be able to understand how the ice is moving and whether it is headed for the sea.

Gogineni has been working with ice sheets since 1992. He said that although the Greenland ice sheets have been losing mass, sea level rise is not an immediate concern.

"I think it's a slow process that could take as much as a hundred years or more," said Gogineni. "But, once you start the process you can't stop it. So you better have an understanding of what will trigger it and what are the causes for the changes."




Rachel Larson is a Kansas University student who is working as a science journalism intern with the Information and Telecommunication Technology Center at KU.

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