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Deeper Oceans

Discussion in 'World Building' started by Jdailey1991, Nov 13, 2015.

  1. Jdailey1991

    Jdailey1991 Troubadour

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    Back home, the oceans of the world vary in depth. Listed here are the averages:


    Arctic Ocean--1205 meters

    Atlantic Ocean--3926 meters

    Southern Ocean--4500 meters

    Indian Ocean--3963 meters

    Pacific Ocean--4028 meters



    In this alternate Earth, the average depths of each ocean are as follows:



    Arctic Ocean--3460 meters

    Atlantic Ocean--4679 meters

    Southern Ocean--2735 meters

    Indian Ocean--3295 meters

    Pacific Ocean--6896 meters



    In this alternate Earth, with the different average depths listed above, what kind of climate would I expect as a result of these differences?


    ("Differences" as in "always there from the start" rather than "changes" or "in the future" or "overnight")
     
  2. Penpilot

    Penpilot Staff Article Team

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    What are the reasons for the increase in depth, and how is the extra depth manifested? I mean if the oceans are just higher, then wouldn't that mean a lot more of the surface is covered by water?

    In addition, I'm no expert, but simple ocean depth may not be the only thing that affects climate. Ocean current's affect weather too. I know the Gulf Stream affects the climates on the East coast of North America and West coast of Europe.
     
  3. Jdailey1991

    Jdailey1991 Troubadour

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    It's just a curiosity based on subtracting the maximum depths of each ocean from the average. In regards to manifestation, it's simply the ocean floor being much closer to the mantle.
     
  4. ThinkerX

    ThinkerX Myth Weaver

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    Hmm...the greater depths would make for a slightly thinner crust. Maybe more seafloor volcanoes. If that's true, then maybe more tsunami type events.

    Apart from that, though, I believe currents matter more than depths, at least within a few hundred meters of the surface.
     
  5. Penpilot

    Penpilot Staff Article Team

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    Hmm... if the ocean floor is closer to the mantel, where did all that extra rock and stuff go? If you just say it's gone and replaced by water, that means the overall weight of the Earth will be lighter because water is less dense than rock. And that's a lot of rock, enough, I think, to affect the rotational speed of the Earth.

    I mean Three Gorges Dam in China, if memory serves, has built up enough water weight behind its walls to slow the rotation of the Earth's day by .06 microseconds per day.

    So if the earth is lighter, would that mean the day's would be shorter?

    Also, as the Earth rotates along its axis and around the sun, there's a water bulge in the middle created by the rotation of the Earth, and the gravitational pull of the sun. So if there's more water, would that mean the bulges would be bigger? This could affect tides and the severity of them.

    I don't know. Those are just things that come to mind when spit-balling this.
     
  6. Jdailey1991

    Jdailey1991 Troubadour

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    Subduction and divergence are still apparent.
     
  7. Velka

    Velka Sage

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    Deeper oceans would definitely have an impact on the world.

    Wind drives the currents of the first 100 metres of the ocean, but there is the phenomenon of a global ocean 'conveyor belt' which are currents that move thousands of metres below the surface and keep the oceans, as a whole, in constant movement through thermohaline circulation. Cold, salty ocean water is higher in density and therefore sinks to the bottom, while the warmer water moves to surface. If the ocean is significantly deeper, one would posit that the water would be significantly colder at the bottom, which may cause more, or perhaps less, movement.

    When the water moving through the conveyor belt hits the arctic regions it gets colder, sinks, and is replaced by the warmer water moving in. Some of it freezes into sea ice and ice bergs, making the surrounding water saltier (as the salt in the water doesn't freeze). This increased salinity makes the surrounding water denser and causes it to sink.

    The conveyor belt also contributes to ocean carbon dioxide and nutrient cycles. As the surface water warms, this gets depleted, but then become enriched as they move through the conveyor belt as deep or bottom layers. The base of the world's food chain depends on this as it is what feeds algae and phytoplankton growth. If the cycle takes longer to complete because of increased depth then the ocean could a richer food chain base.

    It is thought that movement through the whole conveyor belt can take up to 1000 years, deeper oceans means a longer timeframe for one complete cycle.
     
    Last edited: Nov 14, 2015
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  8. Jdailey1991

    Jdailey1991 Troubadour

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    And if a colder ocean bottom alters the movement of the currents, how'd that affect climate?
     
  9. Velka

    Velka Sage

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    I'm not sure, you've asked a very complicated question due to the existence of feedback loops in our environment.

    Carbon dioxide is a greenhouse gas, it absorbs infrared radiation from the earth, and helps keep the surface warm. It is thought that about 10 gigatonnes of carbon dioxide is absorbed by the ocean a year, primarily though phytoplankton.

    Phytoplankton are like microalgae. They convert water, carbon dioxide, sunlight and nutrients into oxygen and hydrocarbons through photosynthesis.

    When phytoplankton are eaten, or if they die and decompose quickly the carbon dioxide is returned to the atmosphere, this also negates the oxygen they create, due to bacteria using it up. If they die and sink to the bottom, before they decompose, the carbon is stored in the deep ocean where it remains until the global conveyor belt eventually pulls it back up to the surface creating a biological carbon pump.

    If the ocean is deeper, this feedback loop would take longer to complete. One could argue that this would result in an overall reduction of carbon dioxide in the atmosphere.

    However, you would have to take into consideration that if the longer cycle of the conveyor belt could result in more nutrient rich water being pushed to the surface (it has longer to replenish) then phytoplankton growth could go into overdrive creating harmful blooms. Some species of phytoplankton create powerful biotoxins which result in 'red tides', also a mass growth/death cycle would create a huge surge in bacteria growth to eat the decomposing organic matter which would significantly deplete oxygen levels in the water, causing mass death of other aquatic life.

    Phytoplankton also create dimethyl sulfide that promotes the formation of clouds over the ocean surface. Sunlight reacts to it, changing it into sulfate aerosols - these are microscopic particles that cause water vapour to condense and form clouds. About 1/3 of energy from the sun is reflected by clouds which influences our surface temperature. An increase in cloud density and formation would lead to cooler surface temperatures.

    But, it isn't that easy (of course). Everything is a feedback loop. More cloud coverage, would lead to less sunlight, which in turn would lead to less phytoplankton growth (due to needing photosynthesis to survive). Less phytoplankton would mean less sulfate aerosols, which would then lead to a reduction in cloud cover.

    Perhaps all this would lead to a climate that wildly changes due to these loops - huge drops in temperature when the
    phytoplankton are in full swing, massive warm spells when they essentially kill themselves due to overproduction dimethyl sulfide. This isn't even taking into account how this would affect zooplankton (main consumer of phytoplankton).

    Now that I think about it, (and stop thinking about phytoplankton for a second), increased cloud cover would also change the rate of evaporation from oceans which would significantly reduce the amount of precipitation as well.

    I don't have a concrete answer for you, the interconnectivity of the earth and it's oceans is a very deep (pun intended) idea. Like I said, this is a very complicated question :)
     
  10. Brian G Turner

    Brian G Turner Scribe

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    I need to ask - why are you throwing figures about if you don't understand them? If you're writing a story then any details about ocean depths will be almost completely irrelevant under any envisaged scenario. However, if you are starting from the point of having a specific atmospheric effect you want to try and engineer, then that would be fine.
     
  11. Jdailey1991

    Jdailey1991 Troubadour

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    Because I can't have the okay to go through with it if I get to a boat without a paddle.
     
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