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Writing: Input Wanted What if sea level rose dramatically?

  1. May 13, 2017 #1
    I'm working on an idea set on an Earth where the ice caps have melted. I'm curious about New York City in particular, how far Manhattan would be from the new coastline, how many towers would still poke up out of the Atlantic and how much would still be above water. Also curious where the best location for New New York, for lack of a better name right now, might be.

    I can likely get away with fudging it by not specifying the name of the submerged old city and saying whatever I want accordingly, but I think it would be better with a few concrete details.

    I know Nat Geo used to have a zoomable interactive map on the topic, but they seem to have taken that down. Would love it if anyone could point me to a relevant screenshot. Google Maps doesn't seem to have a feature to raise sea level by 216 feet.

  2. jcsd
  3. May 13, 2017 #2
  4. May 13, 2017 #3


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    What kind of input would you like? That website seems to answer most of your questions, or at least gives your a good place to start.
  5. May 13, 2017 #4
    It sounds like OP wants to know what are realistic sea level reactions to various events. What is the right sea level for all the ice melting? (Not Waterworld, obviously.) What is the fastest that sea level could plausibly rise?

    Could a terrorist detonate a nuke in Antarctica and slide a big ice sheet into the sea? (Assumes a terrorist who understood glacial flow.) How fast would the resulting wave move? Imagine turning on the radio and hearing that global sea levels are going to rise by 12 inches tomorrow, so get out of town!

    Edit: Why do these maps always show what is going to happen to New York? Lots of people WANT New York to flood. To get some political traction, show them what is going to happen to Charleston.
    Last edited: May 13, 2017
  6. May 13, 2017 #5
    If all the ice in Antarctica would melt the oceans would rise about 200 ft. It has 90% of the Earth's ice. So if all the Earths ice melts the sea level would rise
    about 222 ft.
  7. May 13, 2017 #6
    That slider is in meters, right? So "60m" is 196 feet.
  8. May 13, 2017 #7
    Yes, Algr, that's sort of what I'm looking for so I can give a semi-plausible historical backstory. I want the story to take place after the water has risen as a side effect of global warming. (No, terrorists, sorry.) So, If anyone has an idea of what percentage of global ice the major ice shelves have (for instance, I read somewhere recently that Antarctica has 90% of the world's ice) and in what order they're most likely to fall into the sea (if anyone has a guess on that) that kind of info would be great.

    When major ice shelves fall into the sea, what is the tidal wave damage potential? Would Greenland threaten Western Europe/Eastern Seaboard?

    Also, the buildings with their foundations underwater: would I be correct assuming that can't be good for structural integrity? How many years could they conceivably stand before toppling into the sea?

    That's about it for now. Thanks for bearing with me!
  9. May 14, 2017 #8
    Other questions I have, now that I've had time to sleep on it...

    1. The National Geographic article that sparked this said the average world temp would rise from 58 to 80 F. Does this mean that if I looked at today's average temperatures for a given region and multiplied by 1.38 (80/58) I could have a rough idea of how hot it would be?

    2. With more liquid water, will there be more cloud cover worldwide? More rain? Will the higher temperatures lead to more violent weather?

    3. The worst case scenario sim I've been running show the Hudson and the St. Lawrence rivers eventually joining to make a big island of the Northeast. I assume this water will eventually become saline? Would I be correct assuming this would be detrimental to freshwater life in the rivers and Lake Champlain (where they'll meet)?

    That's it for now. Thanks?
  10. May 14, 2017 #9


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    You can see any part of the world on that map. Just scroll around!
    Interestingly, Japan barely had a dent put into it even with a 60m sea level rise. Well, perhaps a bit more than a "dent". I just never realized that Japans terrain was so mountainous.

    Unfortunately I doubt it's as easy as simply adding in a multiplier and increasing the temperature. That kind of temperature change would drastically alter weather patterns all over the world. Who knows what kind of local climate you'd have somewhere. Wet areas may become deserts and dry areas may become swamps.

    Hmm. My first, naive thought is that the increase in temperature would increase the evaporation rate of water and increase the average rainfall worldwide. But I'm certainly not a climatologist or someone else who'd know.

    I believe so.
  11. May 17, 2017 #10
    The thing is: New York City has a lot of money and people. We'd simply figure out how to keep the water at bay, rather than letting it into the city. Because of the last round of hurricanes, were able to pump the city out pretty well and if sea level rose, it'd be slowly enough that we could stay on top of it. Most of the country of The Neatherlands is below sea level. As long as the world order is maintained, NYC will always have the money to stay dry.
  12. May 17, 2017 #11
    While I agree there would be areas far worse off than NYC, such as Denmark and Bangladesh which will be 100% submerged in this scenario, I don't think this is a problem that money can fix. We're talking about roughly 200 feet of water here, and there's only 135 ft clearance below the Brooklyn Bridge. Keeping Manhattan dry would take a Herculean effort, to the point where I think the money would say it makes more sense to relocate. But that's just my first impressions. I'd love to hear arguments for and against.
  13. May 17, 2017 #12


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    Trying to keep the waters from reaching New York City is problematic. Unlike some other cities that are lower than sea level, New York City is literally surrounded by water. There are no "choke points" that you can damn off to keep the water out. You'd have to build huge walls around the city capable of holding against an immense amount of pressure. Imagine the Hoover Damn but dozens of miles long and without any canyon walls in which to anchor it.
  14. May 18, 2017 #13


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    The economic cost of this would be beyond staggering. It's currently estimated that well over half a billion people live in Low Elevation Coastal Zones which are defined as being <10m above sea level. Something like 150 million of these are in megacities. A rising sea level up to 60m would result in displacement of at least one in ten people on the planet and the flooding of some of the most important/richest cities on Earth:

    I expect global geopolitics and economics would be radically different in such a world with nations with low coastal populations and significant industrial/economic assets away from the coast taking positions as global powers. Several nations likely would have collapsed completely under the strain.

    EDIT: Using the sea level map posted earlier in thread and this list of cities by GDP 70% of the top ten richest cities would be devastated by sea level rise, being either coastal or river based. A quick calculation suggests that's somewhere near to $7 trillion dollars in GDP gone, about 10% of the world's real economy. That alone would be devastating but beyond that you have hundreds of billions displaced.
    Last edited: May 18, 2017
  15. May 18, 2017 #14


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    Has anyone else done the maths on how much energy it would take to melt the antarctic ice sheet?
    I did, and it was staggering.

    But this is Sci-Fi, so no big deal if anyone hasn't.

    Fun thought experiment though.

    ps. I got yelled at on Facebook for publishing my findings. Apparently I'm now a "Climate Change Denier". :bugeye:
    pps. But he's a hippie, so I didn't get too upset. :oldbiggrin:
    We'll all be dead long before all that ice melts.
    Required the energy of the equivalent of 20 Columbia River Basalt Group flows to melt all the ice.
  16. May 18, 2017 #15
    Global Climate Change deniers are fond of stating that when an ice cube melts in your glass there is no increase in level. I suppose they choose to ignore that the ice in glaciers of all kinds are either on land or attached to land. So I counter with - Take a full glass of water and drop an ice cube or two into the glass. The Antarctic Ice Sheet doesn't have to melt. It only needs to become detached from land and fall into the sea to have a substantial effect.
  17. May 18, 2017 #16


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    Oh! I just had an idea, given that it takes between 2.3(whackadoodle methods*) and 250,000(current loss trend) years in my various scenarios to melt all the ice.

    I've heard that fresh water is going to be a scarce commodity.
    What if water poor nations started harvesting antarctica's ice?
    I'll have to collect some numbers for that.

    How much water is used to grow all my food?
    How much water do I use?
    What if 20 billion people wanted to use that much water?

    google google google

    Oh my god!
    "...a simple cheese sandwich takes about 56 gallons of water...
    ...a single pound of beef takes, on average, 1,800 gallons of water..."


    maths maths maths

    292 years! Eureka! (Based on everyone eating six 1/4 lb cheeseburgers a day)

    2017+292 = 2309

    That's well before the year most life would perish from the current warming trend. (see #4 below)

    whackadoodle methods:
    1. Use tsar bombas! It would would only require about 45,000,000 of them.
    2. Build a giant mirror in outer space, the diameter of the earth, and point it at antarctica. Time to melt: Only 2.3 years! (Probably more, as ice is pretty reflective. Let's guess 30 years.)
    3. Divert all human sources of energy to antarctica. Time to melt: 17,000 years.
    4. Year the average temperature on earth reaches 40°C at the current trend: 3340. I'm guessing most humans would be dead from the heat by then.​

    Disclaimer: I've only been studying climate change for 4 days, so all of my numbers should be considered only suitable for fiction, even though they are based on actual numbers. If climate change maths was easy, then people wouldn't be arguing about it.
  18. May 18, 2017 #17


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    For a more realistic sea level rise of a few meters, you can build dams. The Netherlands do this on a large scale, 1/4 of their land area is below sea level (half of it has been drained artificially). New York could certainly afford such a dam, most other cities in the US and Europa as well. But that is a few meters. A 60 meter dam around a whole city would be ... ambitious.

    The Cochiti Dam is 76 meter tall and 8850 meters long, with construction costs of at least $100 million in 1960 dollars (not clear how much it did actually cost), or rougly $1 billion today. Saving most of New York would need at least ~150 km dam, and rerouting the Hudson completely. We are probably talking about more than $100 billions. About $10000 for everyone now living below sea level. Not completely impossible, but a gigantic construction project. The high population density of New York and the high per capita GDP make that somewhat possible, but most areas cannot afford that.
  19. May 23, 2017 #18
    Remember when saying that something will cost 100 billion dollars, you have to compare that to the GDP. The GDP of NYC alone, is above 1.5 trillion dollars. Is it cheaper to spend 8% of your GDP walling off the city, or abandon the second most profitable city on Earth. Honestly, it's probably cheaper to build that dam.
  20. May 23, 2017 #19


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    I still have doubts about such a dam even being possible. And serious doubts about the cost being only 100 billion dollars.
  21. May 23, 2017 #20
    But if we're talking about hundreds of feet of sea level rise, aren't we also talking about hundreds of years worth of technological progress?

    By the end of this century, we'll only need to figure out how to push back maybe 6 feet of water. That's certainly doable.
  22. May 23, 2017 #21


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    hmmmm.... Maybe we could adapt, and rename NYC; New Venice?


    Just watched "AI" the other night, as I seemed to remember NYC being under water.

    The intro to the movie is basically Chatterton's theme; Blah blah blah, water rose, blah blah blah.

    Hours later, I decided that Hollywood exaggerated sea level rise.
    Bad Hollywood!

  23. May 23, 2017 #22


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    WRT making a vast dam around NYC, I was concerned about how permeable/impermeable and strong the ground was in the are since any dam would have to join to the bedrock underneath to stay put and to make a water tight barrier.
    Fortunately for NYC it turns out it is on schist from eroded mountains. Some say the tallest of NYC's buildings are where the bedrock is closest to the surface. This of course raises questions about other areas of the city. An extreme example might be Bangladesh, which is a giant alluvial plan. Probably very leaky soil. Not a good place for a dam I would think.

    An alternative idea to either moving out or putting a dam around NYC might be a series of smallish (compared to the dam) interconnected underwater domes. Smaller size, greater curvature of the surface, easier to make strong. Of course that would drastically change the way the city looks and might limit building height. On the other hand, one could choose which areas to save and let others go.

    I think the statue of Liberty would just get moved. Its on a low island and is hollow.
    Also you throw some ghost buster slime on it and it could move itself.
  24. Jul 9, 2017 #23
  25. Jul 9, 2017 #24
    Yep the Dutch have been successfully addressing this problem for more than 2 centuries.
    I was talking to somebody recently, asking how the system works.
    I gather that there is the actual sea wall itself, and within that there are 3 levels of pumps raising the water up in stages,
    the upper stage is released to the sea at low tide.
  26. Jul 10, 2017 #25


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    Now that you mention this, I think that given enough time, building a giant sea wall could work. Spreading the work and cost over decades might make the idea plausible. I wasn't really thinking of a time frame earlier.
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