Could Bridging Gibraltar Save the Mediterranean Region?

June 16, 2016

This video raises a lot of questions, but it does show that dealing with Sea Level rise is going to require a lot of creativity, and resources. Geo-engineering is not just about solar radiation management, it implies that a number of adaptation strategies of this type will be considered.   First step would be to bridge Gibraltar, with the possibility of adding Locks in the future to control Mediterranean water levels.

The video claims that ecological effects to the region would be manageable, but another major objection would be whether building such a structure would itself have a major effect on climate.

There are similar ideations floating around for other regions, like the Baltic.

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13 Responses to “Could Bridging Gibraltar Save the Mediterranean Region?”

  1. Andy Lee Robinson Says:

    Impossible with the resources we have today, including political will.
    14km wide and between 200-1000m deep would require tens of cubic kilometres of landfill! That’s many billions of tonnes of rock and reinforcement that would need to be mined, transported and planted.

    I can’t see it happening, but if desperation ensues as all Mediterranean resorts start going under, then perhaps it could be attempted using all renewable energy.

    It could also double up as a massive tidal generator until sea level rises too high.

    • ubrew12 Says:

      Remember: to start, this ‘dam’ only has to withstand a force equivalent to 6 feet of hydraulic head. Perhaps a membrane supported by a truss structure would be sufficient for the next few centuries.

      • Andy Lee Robinson Says:

        (6 feet + future sea level rise) x 14 km.
        Hydraulic head isn’t the only force it needs to withstand, undersea currents and salinity differences also exert forces.

        It cannot be a ‘wall’ type of wall… it would have to be an artificial peninsular which means building and filling in a new coastline on depths of abyssal magnitude, several kilometers wide as well as long.
        Factoring in the level of slope required for the new landmass to remain stable, the amount of earth required would make the Panama Canal look like a moat around a child’s sandcastle in comparison!

  2. rsmurf Says:

    And since the sea level rise will be kept out of the mediterranean that means more sea level rise for the remainder of the oceans! Crazy idea!!

    • otter17 Says:

      Hmm, that would be an interesting question. How much additional sea level rise could be expected given the Med. Sea is held back? I suppose a rough cut analysis would be to get the figures for the Med. Sea’s surface area relative to total surface area affected by sea level rise (SLR).

      It looks like a NOAA branch is showing data that the Mediterranean has about 0.8% of total ocean area, so there would probably be a measurable rise in SLR given a project like this went forward, maybe something like an additional 1 cm outside the Sea given the project is built when we hit 1m sea level rise total.


  3. Great idea but total SLR is more like a hundred feet by 2125 at the latest. That is a lot of structure to erect. And once erected the Mediterranean would be at constant risk of catastrophic flooding if it were breached.

  4. rayduray Says:

    Damming the Gibraltar Strait was proposed long ago. In the 1930s it was a Nazi public works idea.

    A related civil engineering megaproject proposal with a history back to the 1920s is the Qattara Depression Project.

    https://en.wikipedia.org/wiki/Qattara_Depression_Project

    What I particularly like about the Qattara project, in addition to help regulate sea level rise in the Mediterranean Sea, is that it would also tend to ameliorate the harsh Saharan climate of western Egypt. It would probably become a bird paradise, similar to the Salton Sea in its better days. In fact, a salt water re-fill of the Salton Sea is another megaproject proposal that I think ought to be seriously considered.

  5. redskylite Says:

    I agree with Andy Lee Robinson, this project certainly won’t happen in today’s world, even if the resource could be found. Gibraltar is administered from the U.K, and Spain isn’t too happy about it. Britain is on the cusp of distancing itself from the rest of Europe, even more, with BREXIT. Sadly the thoughts of a unified Europe pulling together to fight climate change is fraught with political diversions, ego’s and self interests.


    • JSYK: This kind of project wouldn’t run from Gibraltar to Africa, it would run from Spanish territory on the other side of the bay. If you check a map, you will see that the region south of Algeciras is actually much closer to Africa.


  6. $275 Billion to damn the Mediterranean at Gibraltar. Would need pump to maintain salinity.

    $2.5 Billion to damn the San Francisco Bay.

    $15B bill for New Orleans new defenses that only protect against storm surge at current sea level.

    National Geographic from November, 2013:

  7. Gingerbaker Says:

    We’d better perfect ancient Roman sea water-resilient concrete construction and just resign ourselves to either leaving the shore or moving all electrical several stories up and living like the Venetians.

  8. schwadevivre Says:

    The ecological problems are huge. We know next to nothing about possible benthic migrations plus the narrowing of the Straights would massively increase the interactions of marine species with ships of many sizes.

    The hydrological problems would also seem to be far bigger than this video makes out. Assuming that the hydraulic head can be kept to 2m the scouring effects of the inflow would still be massive plus there is a slow deep, water outflow that would be entirely blocked. Although I lack the intimate knowledge of the mechanics I find the idea that the head would be kept at 2m to be dubious. Add into the equation that the very strong current such a level diference would create and navigation immediately becomes far more problematic.

    If I recall correctly evaporative loss from the Mediterranean is huge force in the climate of the region and surely the limitation of the cooling inflow will increase that evaporation in the Western Med changing climate in that region.

    On the Eastern side there is the problem that the Suez Canal is unlocked so keeping the Med artificially 2m below general sea level will encourage a net inflow from the Red Sea. Currently north of Great Bitter Lakes the flow is seasonal and south of these reservoirs it is tidal. In essence at present there is no net inflow via the canal. It might be thought that building a lock or locks would be the answer to the problem but there you come up against the problem that you would be adding a bottleneck to an waterway from which they are trying to remove bottlenecks.


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