How much sea level rise will occur with glacial melting?

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PotentialSeaLevelRise2Sea level rise is a serious issue, and the sea is rising because of global warming. How bad can it get?

The USGS has estimated the potential contribution of melting ALL of the glacial ice around the world to sea level rise. This is very rough, because many different factors affect sea level, including ocean temperature, gravity, and current. But this gives a rough idea. If the release of CO2 and other greenhouse gasses continues apace, we could actually see the eventual melt of all of this ice. If we stop releasing these greenhouse gasses in a reasonable time, it is unlikely that these very large numbers will be achieved. But it is important to realize the potential, to understand that the amount of available ice to melt into the sea is so large that that factor in and of itself will not come to our rescue.

I made a map, which is also very approximate, indicating about where the sea will reach in much of North America, and posted it here.

So, the following data are from the USGS. The total is just over 80 meters, which is about 263 feet:

Potential Sea Level Rise

Location Potential Sea Level Rise
East Antarctic Ice Sheet 64.8
West Antarctic Ice Sheet 8.06
Antarctic Peninsula .46
Greenland 6.55
All other ice .45
Total 80.32

Poore, R.Z., Williams, R.S., Jr., and Tracey, Christopher, 2000, Sea level and climate: U.S. Geological Survey Fact Sheet 002–00, 2 p., at

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10 thoughts on “How much sea level rise will occur with glacial melting?

  1. Love the idea for the map. But I wish you had checked it against a topo map first.

    You have the Gulf of Mexico encroaching into Oklahoma along the Red and Arkansas Rivers. But the Red River is at 300 feet elevation at the Oklahoma border, and the Arkansas River is at 400 feet as it leaves OK. I think there are similar problems all along the proposed new seashore. Maybe a problem with the way the colors were interpreted by your map software where ever the slope is gradual. In steeper areas, its fine.

    So the Hudson and Ticonderoga Seaway is valid. That will be a very interesting change to the local geography.

    1. wehappyfew: This is based on topographic data supplied by the USGS. That does not mean it is totally accurate, but I’m not sure why national data supplied by the USGS would be wrong. I don’t think there is an issue of color interpretation by me, because that was just taking the pixels supplied by USGS and deleting all the colors below a certain altitude. There could be a number of reasons why there is a difference between what you are saying and this map, but to begin to think about that you would need to supply information on your sources. Thanks for the comment.

    2. Info sources:
      I just used the free USGS topo maps here:

      Fort Smith AR is the first place I looked, it is on the OK border, elevation 400 feet, GPS Coordinate: 35.3870907, -94.440622

      Again, this is an excellent map. I would love to use it whenever a denialist argues that there’s no major danger from BAU warming. There are a lot of denialists here in the southern US. If they see their local area is slated for submergence, it will hit home.

      But this message is ruined if they can immediately see obvious errors.

  2. I’m not at all sure there are errors. If the maps are different, no particular reason to think the recently created USGS map based on satellite technology is more wrong than the older maps. Topography is tricky!

    1. OK, I’ve looked more closely at your original post from June 18, 2013. You linked to the full-sized USGS map…

      They must have taken a map that used feet and converted it to meters, otherwise the strange choices of elevations make no sense. 8 meters = 25 feet, 54 meters = 175 feet, 114 m = 375 ft, etc

      For that map I see 5 gradations of blue from 0 meters to 114 meters on the map key:

      0 – 8 m = 0 – 25 feet =dark blue
      8 – 54 m = 25 – 175 feet = 2 shades of lighter blue
      54 – 114 = 175 – 375 feet = 2 shades of very light blue

      If we assume the unlabeled subdivisions are midway between the labeled points, then we get this:

      0 – 8 m = Darkest blue = 0 – 25 ft
      8 – 31 m = 2nd blue = 25 – 100 ft
      31 – 54 m = 3rd blue = 100 – 175 ft
      54 – 84 m = 4th blue = 175 – 275 ft
      84 – 114 m = 5th blue = 275 – 375 ft

      So you can make the argument that the 4th blue color should be submerged, even though it is a bit above the 80 meters of total ice to melt. If you add in thermosteric expansion, we should be able to get to 84 meters.

      Looking again at your final map showing future submergence, it looks like you have taken away all blue colors, including the 6th blue from 114 -137 m, and possibly the blue-green color up to 160 meters.

      That’s how you get an ocean bay in central Illinois.

      Look again on the original USGS map at the coastal plain of Texas and Louisiana. It is easiest to see there – each color subdivision is wide enough to distinguish.

      I hate to be so critical, but I think an accurate map of this potential inundation is vital to help communicate the risks. And the Karma aspect of pointing out how BAU will flood out so many deniers in the Red southern states is too good to pass up.

      Thanks again for you efforts.

    2. The scales on those two maps are not the same. I used the map you see in the post, and it is unaltered. The way I did it is correct for about 80 meters if the map is correct. I’m not sure how to reconsile the scale difference, or what the source of that is. I’ve been considering redoing this at some point, maybe sooner than later! But I do not assume the original is wrong simply because there is a difference. Note that in your look comlaring with the other map, some seemed off and some seemed OK. ( If I recall correctly, originally there was no scale and i asked for one to be on… )

      By the way, after i did mine, another was done by NGS and they are very similar.

    3. Looking at it more closely, I think the real numbers may be between what I did before and a 60 meter contour from the “new” USGS map. The newer USGS map seems to be closer to real altitudes than the older one was.

      I am now considering making an entirely new map that sets the ocean at 60 meters, and then shades the zone between 60 and 114. That would represent where the sea would be if most of the glacial ice melt, allowing room for transgression and isostatic effects. So, everywhere below the 60 meter limit would be definitely under water and everything above in the shaded area would vary with local conditions.

  3. In any event, I’m not concerned that a map explicitly described as an approximation does not meet standards of someone who is going to deny that climate change is real anyway! Please see caveats on the original post about inherent inaccuracies of the method. Transgression inaccuracies can be tens of miles wide, vertical isostatic inaccuracies could produce big differences. This is just to give an idea.

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