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How much are sea levels expected to rise by the year 2100?

  1. Aug 3, 2012 #1
    Will they rise slow and gradual allowing for a somewhat seamless transition of population to higher ground, or will there one day be a large storm that will inundate an area permanently?

    What are the implications for the gulf coast, South Florida, and the East Coast?

    How will vital infrastructure such as roads, oil refineries, and cities cope with such rises in sea levels?
  2. jcsd
  3. Aug 3, 2012 #2
    I think it would be interesting to calculate how much water is needed to raise the sea level one foot (for instance). First, since it is a globe, one foot change in radius will increase the surface area by the square of the radius excluding where land mass is, except that by raising the height of the water, more area is available to be covered by water. you would have to figure out what the average gradient is of land within one foot of the current level and add that to the area currently covered by water... hmm

  4. Aug 3, 2012 #3


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    To be honest, no one knows.
  5. Aug 4, 2012 #4
    http://envisat.esa.int/live/envisat_live_04.htm [Broken] you can see the near real time sea level fluctuation.

    And here the recent history
    Last edited by a moderator: May 6, 2017
  6. Aug 10, 2012 #5
    Oceans are going to rise it will be a gradual process. It's kinda pointless discussing otherwise, although, there are a million and one opinions as to why, how and where so the question per se is kinda meaningless..?

    Will there be flooding more than the mean, yes, where we don't know, why is a moot point, although some people have some good ideas. The OP is kinda like asking will there be more people on Earth and will this cause overcrowding: well no in Europe their wont be more people the population is stable and levelling off, in some places decreasing to leave a stable mean population, but elsewhere? You get the analogy. The question is indistinct.
    Last edited: Aug 10, 2012
  7. Aug 11, 2012 #6


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    Here is recent report on sea level rise along the East Coast of the USA from Science News, July 28th, 2012; Vol.182 #2

    East Coast Faces Faster Sea Level Rise
    “We have direct evidence of a hot spot stretching from Cape Hatteras in North Carolina to just above Boston,” says Asbury Sallenger Jr., an oceanographer at the U.S. Geological Survey’s St. Petersburg Coastal and Marine Science Center in Florida. “The area has an unusual sea level rise acceleration compared to the rest of the United States.”

    There is no clear explanation yet of what is causing this accelerated sea level rise.
  8. Aug 12, 2012 #7


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    Sea level rise currently is about 1-3 mm per year and is one of those embarrassing little "loose ends" that no one in the climate community wants to talk about. There seems there is a nearly 100% difference between tidal gauge measurements and satellite based measurements in sea level in recent years. Wikipedia takes a stab at explaining it this way:

    "Current rates of sea level rise from satellite altimetry have been estimated in the range of 2.9–3.4 ± 0.4–0.6 mm per year for 1993–2010.[28][29][30][31][32] This exceeds those from tide gauges. It is unclear whether this represents an increase over the last decades; variability; true differences between satellites and tide gauges; or problems with satellite calibration.[61] Knowing the current altitude of a satellite which can measure sea level to a precision of about 20 millimetres (e.g. the Topex/Poseidon system) is primarily complicated by orbital decay and the difference between the assumed orbit and the earth geoid .[94] This problem is partially corrected by regular re-calibration of satellite altimeters from land stations whose height from MSL is known by surveying. Over water, the height is calibrated from tide gauge data which is needed to correct for tides and atmospheric effects on sea level."


    I can see how having satellites with a precision of 20 millimeters measuring and expected sea level change between 1 and 3mm per year could produce some error. Now add to orbital decay - a 50+ mm per day variation in earth (land) tides where the solid earth bulges unevenly and you have a real potential to make some serious errors especially down in that 1-3mm per year range.


    Living here in FL I go down the road to some houses built on the water (IRL) in the 1950s and that I have been watching since the 1970s and note - they're still about 2 feet above mean high tide and only flood in hurricanes.
  9. Aug 17, 2012 #8
    For some odd reasons, when making this pic yesterday
    https://dl.dropbox.com/u/22026080/cntrls6.jpg [Broken]
    I got curious about how much the water production of burning fossil fuels would contribute to sea level rise, given that all those contrails fall back to earth eventually.

    I would anticipate that it would be negliglibe, but the proof is in the pudding. So if we assume that we produce
    21.3 billion tons CO2 per year and we assume rougly a ratio of CnHn (the rough C/H ratio of liquid fuel, coal is C only but natural gas is CH4), we could calculate that this also produces 4.4 billion tonnes of water per year. However the ocean water surface is some 3.35 x 1014 m2, hence one requires 3.311m2(=tonnes) for one 1mm sea level rise. So it is indeed negliglible. But now we are sure.

    One could wonder what other effects the constant injection of tonnes of water per second has on the tropopause and stratosphere, but that's another non-discussable matter.
    Last edited by a moderator: May 6, 2017
  10. Sep 6, 2012 #9
    As a previous responder has said, making such a prediction with so many variables and complex models is difficult. Short of scientific certainty, an alternative could be to ask the financial market. Bear with me...

    I helped assess the flood risk of new nuclear power stations at specific coastal locations. The plant needs a lot of seawater, c120 tonnes per second, so you don't want to pump it any higher than you absolutely need to. On the other hand you don't want your $10bn investment disappearing under a rising sea like Atlantis.

    We had our own assessment of sea level change but the insurance markets added an extra reference point. By comparing insurance costs for given heights above sea level you start to get a view based on an averaged or broad understanding.

    It's not ideal, but getting someone to put their money on the table certainly focuses minds.

    In answer to your question; at a site in Western Europe we anticipated sea level to rise 100cm over the next century with storm surges up to 7m above mean tides today. Quite a bit more than I had expected.

    Not wishing to open the climate change topic too much, but when folk tell me they don't believe in it, I say "Great, then you'll insure my sea level power station?"
  11. Sep 6, 2012 #10


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    Good post, windfarmer!

    Location also has a great deal to do with whether sea levels will rise or lower. Luckily my parents decided agianst buying a vacation beach house on Galveston Island in the Gulf of Mexico over 40 years ago. Due to erosion from tropical storms and hurricanes over the decades, that entire subdivision no longer exists, it's all under water now.

    This might help muddy the waters. :wink:

  12. Sep 8, 2012 #11
    it's hard to predict. every decade there is another scientist saying civilizations will drown in 20 years.
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