Sea levels rise and fall; our earth as we know it is changing

The United Nations Intergovernmental Panel on Climate Change (IPCC)'s worst projections for Greenland's contribution to sea level rise top out at 68 centimeters (27 inches) by the year 2100. Such a rise would imperil coastal cities around the world.

But Anders Carlson of the University of Wisconsin-Madison and a team of researchers say the problem is potentially a lot worse. They say the oceans could rise by as much as 1.3 meters (4.3 feet) by the end of the century, double the IPCC's estimate.

If the team's findings are right, some 145 million people living within 1 meter (3.3 feet) of sea level would be in danger. By one United Nations calculation, a meter rise in the oceans would cost the world $944 billion in damages and lost productivity.

Ian Walker, of the University of Victoria, says Canada has the longest coastline in the world and more than 80 per cent of it is submerging due to rising sea levels. But even areas where the sea level is stable are at risk, he says, because of the greater frequency of storms, particularly on the Pacific coast.

"The greatest concern is areas that are highly developed. Richmond is at or below sea level and it's one of the most densely developed and developing areas in greater Vancouver," Walker said.

The entire 50 square-kilometer (19 square-mile) Markham Ice Shelf off the coast of Ellesmere Island broke away in early August and is now adrift, while two sections of the nearby Serson Ice Shelf detached, reducing its mass by 60 percent or 122 square kilometers (47 square miles).

Ward Hunt Ice Shelf, which halved in July, lost an additional 22 square kilometers (8.5 square miles).

"These changes are irreversible under the present climate and indicate that the environmental conditions that have kept these ice shelves in balance for 4,000 years are no longer present," said Trent University's polar expert Derek Mueller.

"Usually the ice shelves would use the winter to recover from the previous summer. They would reform, ... but the ice shelf can't recover in the winter anymore."

"We have now reached a threshold where (the environment) is too warm for these ice shelves to exist anymore," he said. "What it tells us is that the Arctic is changing."

"This is a discussion that should have occurred after Katrina," said Roy Dokka of Louisiana State University. Dokka has been outspoken about the measurable rates of subsidence -- the process by which land slips below sea level -- in New Orleans and other coastal areas. His work indicates that larger geological forces, far beyond the control of humans, are causing parts of New Orleans to sink.

"New Orleans is going to last as long as people decide that they want to do this and as long as the U.S. taxpayers want to spend money propping it up," said Dokka. Other, smaller communities will not fare so well, he said, because there is little or no money to save them. "New Orleans will last as long as people are willing to put up a struggle. But nature will keep punching until people give up."

"I think we've got our priorities wrong on this," said Tornqvist. "No matter what we do as far as building levees and restoring wetlands, if we don't address global warming, it's pointless."

"Talking about the town of New Orleans itself is kind of tricky," says shorelines researcher Rob Young of Western Carolina University. "If we wanted to spend a lot of money, we could defend the city for some time. It's one of America's cultural draws."

On the other hand, he gives smaller communities in the area a life expectancy of about 10 years. Nor will tearing down levees to restore wetlands help, Young said, adding that the popular belief that wetlands protect communities against storm surges is all wet.

"We wouldn't go into New Orleans, which is still trying to recover from the effects of Katrina, and say 'get out'," said Sandra Eslinger of the National Oceanic and Atmospheric Administration. "That's not an option."

Instead, she says she tries to encourage rebuilding infrastructure with an eye toward what the area is going to look like in the next 50 or 100 years.

In the short term, that means rebuilding the levees so they hold back water successfully. It also means raising houses as an added level of protection, should the levees fail.