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Thread: Is there any way to keep the sea-leve froml rising by digging inland seas?

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    Is there any way to keep the sea-leve froml rising by digging inland seas?

    So a projected rise in sea-level by 2100 is 1.5metres, which is 1.5cm/year from 2000 to 2100, which amounts to a volume increase in the sea of 5400kms per year.

    Would it perhaps be possible to keep the sea-level from rising by digging inland seas that would take an overspill of water from the oceans?

    I know that would be a huge ongoing engineering project, and amount to the digging of giant inland seas of 30m by 22km by 22km, each day.

    This at least shows the scale of the problem...It's always really surprising how much water is held in the form of glaciers etc.

    (unless I got my calculation wrong)
    Last edited by WaxRubiks; 2019-Mar-06 at 08:58 AM.
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    I'm assuming that your 5,400 figure is correct, and that it's in cubic kilometers. By that measure, that's just a little less than half the volume of Lake Superior, the largest inland water body in North America. So we'd just have to dig one of those every two years. Or, looking at things another way, the Panama Canal was one of the largest feats of excavation ever. From here, it looks like between the original French construction company and the Americans, they excavated about 310 million cubic yards, which is less than a quarter of a cubic kilometer. So all we need to do is about 22,000 Panama Canal's worth of excavation every year. The original canal was done with pretty old technology, but it was recently expanded between 2007 and 2016. I couldn't find exact figures for how much was excavated in the expansion, but it sounds like the amount of work was at least on the same order of magnitude as the original. So we need to step up the pace on our digging a little (i.e., by a factor of about 200,000) if we want to try this.
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    If memory serves there was talk several years ago about building a canal from the Med Sea to connect with a large death valley like basin located in Lybia. This would create an inland sea while taking some pressure off of rising sea levels elsewhere. It would seem to be an easier solution to use a natual basin rather than digging one out.

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    Quote Originally Posted by Spacedude View Post
    If memory serves there was talk several years ago about building a canal from the Med Sea to connect with a large death valley like basin located in Lybia. This would create an inland sea while taking some pressure off of rising sea levels elsewhere. It would seem to be an easier solution to use a natual basin rather than digging one out.
    oh yes, I was thinking that, and I think there may be other land areas under sea level in some other places as well, but in the long run, it wouldn't be enough.
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    Quote Originally Posted by Grey View Post
    I'm assuming that your 5,400 figure is correct, and that it's in cubic kilometers. By that measur.
    yes, I think I made a few errors about the numbers at first, and after a few edits, the 'cubic' must have been lost...
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    Quote Originally Posted by WaxRubiks View Post
    oh yes, I was thinking that, and I think there may be other land areas under sea level in some other places as well, but in the long run, it wouldn't be enough.
    Yes, that seems like the only option that would be even remotely practical. Actually, if the sea level rises high enough, the ocean will do this on its own, without any intervention on our part at all. But I think that in most cases, the intervening land is high enough that this won't happen very soon.
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    Quote Originally Posted by WaxRubiks View Post
    Would it perhaps be possible to keep the sea-level from rising by digging inland seas that would take an overspill of water from the oceans?
    Iím not sure how useful that would be. The problem with rising sea level is that it takes away land. So essentially you are just taking away land in A to save land in B. You can choose the location, which might be desirable, and you would be able to minimize land loss to some extent by making the lakes very deep, but otherwise itís a bit like digging a hole to fill a different hole.


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    Quote Originally Posted by Jens View Post
    I’m not sure how useful that would be. The problem with rising sea level is that it takes away land. So essentially you are just taking away land in A to save land in B. You can choose the location, which might be desirable, and you would be able to minimize land loss to some extent by making the lakes very deep, but otherwise it’s a bit like digging a hole to fill a different hole.
    Yes

    Several other things. First, as Grey said, you'd basically be creating a Great Lake every year. Bodies of water that large impact region climate, for example the lake-effect snow (and rain) around the Great Lakes. So you'd be introducing other climate changes that might not be desirable in those areas.

    Second, where are you going to put all that dirt you dig up? Not only are you creating a Great Lake every year, you are creating a new mountain (which will also have regional effects). What about the farmers who are in the rain shadow of that new mountain.

    Third, how much energy is all this earth moving going to take? What is the energy source? Are you using gasoline or diesel for all that equipment? You might be making more problems than you are fixing.

    Lastly, with all these geo-engineering projects, they are going to have effects well beyond the countries that they are done in. As I said in the Solar Shield thread, the political consequences of these projects are very non-trivial; there are going to be winners and losers. It might be fun to speculate on the pure engineering of these projects, but that is very much not real world.
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    It has been shown that a sea wall, a small example of moving land around, can contain a vast area of dry land below sea level. There are sure to be more of those as sea levels rise. Walls are an effective use of manipulation compared with building mountains.
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    Quote Originally Posted by Swift View Post
    Third, how much energy is all this earth moving going to take? What is the energy source? Are you using gasoline or diesel for all that equipment? You might be making more problems than you are fixing.
    Yes, good point about the energy and the environmental effects. It's really counterproductive if you end up burning more fossil fuels to do this geoforming and then change the climate even more.
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    Go deeper instead. Dredge out the centers of the oceans and use the material to build up the shorelines and lowlands. Even harder to do but we don't lose land area and there's less environmental impact if you stick to the already deepest parts.

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    Quote Originally Posted by Jens View Post
    Yes, good point about the energy and the environmental effects. It's really counterproductive if you end up burning more fossil fuels to do this geoforming and then change the climate even more.
    yes, I considered the fuel aspect, but assume that some kind of zero carbon emission fuel will eventually be developed, and then you might still have to deal with some sea level rising.

    As to land loss...there is a lot of expensive real estate near sea coasts, to name New York and London for two..London already has the Thames Barrier....it is quite near sea level.

    If you could build artificial lakes you can choose the area. Like you have the whole of the Sahara Desert to maybe shift sand and rock...I did wonder about the effect on the local weather like with the Sahara Desert...the desert is supposed to be produced by the Hadley Cell movement of air...air from the equator area moves north, falls, and warms up, raising its dew point(?) so there is less cloud formation, and rain at that latitude....I was wondering what turning the desert to sea might do to the weather there.
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    also I wondered if you created inland seas in the Sahara, maybe it could be used for desalination processes to grow food in the region...if you think of hydroponics farming.
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    Quote Originally Posted by Bearded One View Post
    Go deeper instead. Dredge out the centers of the oceans and use the material to build up the shorelines and lowlands. Even harder to do but we don't lose land area and there's less environmental impact if you stick to the already deepest parts.
    you might release a lot of methane digging up the ocean beds, and mess up the local eco-system.
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    Quote Originally Posted by WaxRubiks View Post
    So a projected rise in sea-level by 2100 is 1.5metres, which is 1.5cm/year from 2000 to 2100, which amounts to a volume increase in the sea of 5400kms per year.
    The area of the sea is 361 million km^2. Your 5.4 K volume is derived by keeping that area (5.4=3.6x1.5), ignoring that the water would flow onto low lying countries like Bangladesh, Florida, Vietnam, China, Benelux, etc, increasing the total ocean area by a non trivial amount. If the projection of 1.5m increased the sea area to 500m km^3, it would require extra water volume of about 7K km^3.

    For comparison, the Antarctic ice sheet has 26 million km^3 of ice which would raise sea level by 70 metres if it all melted.
    Quote Originally Posted by WaxRubiks View Post

    Would it perhaps be possible to keep the sea-level from rising by digging inland seas that would take an overspill of water from the oceans?
    No it would not. The diversion of resources and energy into this project would be far less economic than stopping the melt by directly cooling the poles with methods such as sulphur or iron or cloud brightening, and then preventing further warming by directly removing more carbon from the air and sea than total emissions. The inland sea project would be hard to continue during the chaos of oceanic upheavals like acidification and flooding and the risk of tipping points like disruption of ocean currents.

    I know that would be a huge ongoing engineering project, and amount to the digging of giant inland seas of 30m by 22km by 22km, each day.
    https://geology.com/below-sea-level/ is a handy list of land below sea level but it does not give volumes or areas. This map shows the relatively tiny proportion of Australia that is below sea level.
    Quote Originally Posted by WaxRubiks View Post

    This at least shows the scale of the problem...It's always really surprising how much water is held in the form of glaciers etc.

    (unless I got my calculation wrong)
    Yes, it is a big problem. Some useful resources are linked at http://www.johnenglander.net/sea-level-rise-resources/
    Last edited by Robert Tulip; 2019-Mar-14 at 02:35 PM.

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    Quote Originally Posted by Robert Tulip View Post
    The area of the sea is 361 million km^2. Your 5.4 K volume is derived by keeping that area (5.4=3.6x1.5), ignoring that the water would flow onto low lying countries like Bangladesh, Florida, Vietnam, China, Benelux, etc, increasing the total ocean area by a non trivial amount. If the projection of 1.5m increased the sea area to 500m km^3, it would require extra water volume of about 7K km^3.
    yes, I did assume that to make the calculation easier. 7 cubic kilometres is only 0.13% of the total water that would have entered the sea system though.
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    Diggers would have to be solar or nuke powered, or we'd seriously up carbon dioxide production.
    Also, no forest or permafrost destruction allowed.
    Pushing back the Texas coast might work for a few years, As might making a shorter, yet taller Florida.
    The later might either kill the Gulf stream, or let Hurricanes rake east to west from east coast to Mexico.

    I'm not seeing it as possible, even without accounting for the sinkage we'd produce on land we piled dirt on top of.

    I still favor hitting the Greenland ice sheet with a 5km asteroid to bring on a cold phase.

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