Warming to Cause Catastrophic Rise in Sea Level?

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The climate change is likely to impact ecosystems, agriculture, and the spread of disease. An international study published in the science journal Nature earlier this year predicted that climate change could drive more than a million species towards extinction by the year 2050.

"Global warming is a serious threat to biodiversity," said Jay Malcolm, a forestry professor at the University of Toronto. "As climates warm, more southerly species will begin appearing further north, and species that occur at lower altitudes will start showing up at higher altitudes … species will find themselves in habitats where they don't belong."


Glaciers and sea ice in both the Northern and Southern Hemispheres are already melting at a rapid pace, placing animals like polar bears at risk.

"Polar bears are entirely dependent on sea ice," Malcolm said. "You lose sea ice, you lose polar bears."

So far, the rise in sea level is because warmer water takes up more room than colder water, which makes sea levels go up, a process known as thermal expansion.

"The real question is what's going to happen to Greenland and Antarctica," Stouffer said. "That's where the bulk of all the fresh water is tied up."

A recent Nature study suggested that Greenland's ice sheet will begin to melt if the temperature there rises by 3 degrees Celsius (5.4 degrees Fahrenheit). That is something many scientists think is likely to happen in another hundred years.

The complete melting of Greenland would raise sea levels by 7 meters (23 feet). But even a partial melting would cause a one-meter (three-foot) rise. Such a rise would have a devastating impact on low-lying island countries, such as the Indian Ocean's Maldives, which would be entirely submerged.

Densely populated areas like the Nile Delta and parts of Bangladesh would become uninhabitable, potentially driving hundreds of millions of people from their land.

A one-meter sea level rise would wreak particular havoc on the Gulf Coast and eastern seaboard of the United States.

"No one will be free from this," said Overpeck, whose maps show that every U.S. East Coast city from Boston to Miami would be swamped. A one-meter sea rise in New Orleans, Overpeck said, would mean "no more Mardi Gras."

Other scientists emphasize that such doomsday scenarios may be hundreds of years in the future.

"You can't say with any certainty that sea level rises are going to have a huge impact on society," Stouffer said. "Who knows what the planet will look like 500 years from now?"

Future Generations

Most climate scientists, however, agree that global warming is a threat that has gone unchecked for too long.

"Is society aware of the seriousness of climate warning? I don't think so," said Marianne Douglas, a geology professor at the University of Toronto. "If we were, we'd all be leading our lives differently. We'd see a society that embraced alternative sources of energy, with less dependency on fossil fuels."

Overpeck says passing on the problem of global warming to future generations is like ignoring a government budget deficit. "Except with the deficit, there are economic mechanisms that could be put in place to get out of the large deficit," he said. "With sea level rise, there's really no technological way to put the ice back on Greenland."

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Related Websites
University of Arizona Department of Geosciences Environmental Studies Laboratory
Geophysical Fluid Dynamics Laboratory
University of Toronto Department of Forestry
University of Toronto Department of Geology

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