What will coastal cities do when/if the oceans rise too high?

I am watching a show about extreme climate changes on the Science Channel right now and they are talking about how cities like New York will need complex systems of levies and walls with-in the next 500 years as water levels rise. Looking at the computer graphic they are showing it appears like there would need to be a wall or high levy system around nearly all large coastal cities… And those living on the coast are just plain out of luck! Can you picture New York as a walled city? What do you think governments will do in reality when water levels rise to a degree where 5th Avenue is 30 feet under water?
They are saying a global rise of just 1cm would make New York look like a marsh and Florida’s land area decrease by nearly 3/4…

Something is off here. Granted, I’ve never been to Florida, but I have a hard time believing that 3/4 of the state is less than 1 centimeter above sea level.

You mean IF, of course. And secondly, 500 years is a long time. 500 years ago, NYC didn’t even exist; 500 years from now, it may not exist either. It most certainly won’t exist as we know it today. So it’s kind of silly to speculate about 5th Avenue being under water, though it would make a kick-ass dive site.

Anywho, to answer your question, like people have done throughout time, no matter what, the people will adjust. For an example of what the politicians will do, I’d look to New Orleans. They have committees now deciding what parts of the city to rebuild and what parts to level and allow nature to re-claim. At some point, it becomes far too expensive and/or dangerous to rely on levies and dams to keep the sea at bay. So the government will probably buy back the most precarious land and allow it to return to swamp.

And the people will move inland.

The positive thing is that we are not hurting for land here in the United States given our current population. If all remains the same (ha!), our dilemma caused by rising sea levels would not be nearly as critical in comparison to someplace like Japan.

Unless it’s accompanied by a massive climate and ecological change 1cm isn’t gonna do anything to Florida. Even if all the ice in the Northern Hemisphere melted we wouldn’t disappear, although maybe all the big cities except Orlando and Tallahassee would :eek:

Now, if Antarctica fully melted, that’s another story…

Apparently what the program said is that 1cm increase globally throughout the oceans would raise the tidal plane more than 3 meters… I dunno it sounded off to me as well.

Here’s a possibly interesting page that let’s you play with the world’s sea level. You can raise the level up to 14 meters and look at the effects on the coastlines. Some highlights of this game, at the full 14 m:

[ol]
[li]About a fifth of Florida is underwater, mostly in the south.[/li][li]About half of Maryland’s eastern shore is gone. Baltimore’s Inner Harbor, not much fun to visit anymore.[/li][li]Manhattan doesn’t fare too badly, but the southern shore of Long Island is inundated.[/li][li]Central Boston is in big trouble. Logan Airport entirely underwater. Expect major delays.[/li][li]The southern third of Lousiana is swamped, as if they need that right now.[/li][li]Sacramento is wiped out. (Kind of surprising, that one.)[/li][li]In foreign news, the Netherlands pretty much cease to be — unless maybe the Dutch raise their dikes a lot higher. In England, Yorkshire and the East Midlands are getting pretty damp as well.[/li][/ol]

This software might not account for obstacles in the terrain. It might only be paying attention to altitude, while ignoring ridges that would block incoming sea water — at least up to some point. In fact, looking at south central Australia, and the big new lake emerging from nowhere, I think this must be the case.

Considering how Trenton is right on the Delaware River, it was quite comforting to see that at +14 feet, the water stops about a hundred feet from my house :slight_smile:

Realistically it’s not entirely an issue of speculation. The Maldive Islands, a group of islands located in the Indian Islands, is the world’s lowest-lying country; their most populated island rises no more than four meters above sea level, if I recall correctly. For them, the rises of seawaters due ot global warming is already causing problems. The solution they’ve chosen is twofold: build barriers around the larger islands, and evacuate the lowest-lying ones. This is not an abstract plan for the future, it’s something that’s already in progress.

Another factor worth noting is that not only are sea levels rising, but in some places cities are sinking. New Orleans and much of southern Louisiana are slowly sinking for natural reasons. In other areas, land has moved downwards because too much fresh water was removed from aquifers. There was a brief article about this in Scientific American last fall. Parts of San Diego have fallen twenty feet over the last century and a half.

Ultimately, I’m sure we have the technical capacity to build walls around the cities. For me, the question is whether we’ll dedicate enough resources in the necessary places, and whether we’ll have the political will to do a good job. You don’t want the wall around Miami to be a lazy, slipshod job.