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I found the rising oceans story with regard to this island hard to believe when I read somewhere that a neighboring island’s shores are doing just fine. Rising

I found the rising oceans story with regard to this island hard to believe when I read somewhere that a neighboring island’s shores are doing just fine. Rising oceans ought to affect neighbors as well. And further, here we read that the mass is growing. My guess is the island’s foundations are sinking. Don’t label me as a climate change denier; I’m too cautious for that. But I am quite suspicious of the narriative as regards this island chain. I have a special place in my heart for the island: My first domain was a .tv :-)

madaxe_again 9y ago
Sea level rise isn’t uniform, even on a relatively local scale - while the total volume does inevitably increase, variations such as currents, prevailing winds, standing barometric anomalies and even gravitational variations (thicker crust = shallower ocean) influence relative rise. Here’s a picture illustrating this: http://www.soest.hawaii.edu/coasts/sealevel/MSL_Map_MERGED_Global_IB_RWT_NoGIA_Adjust.png http://www.soest.hawaii.edu/coasts/sealevel/MSL_Map_MERGED_G...
- jackhack 9y ago
  When an explanation for global cooling/warming/change puts one at odds with Archimedes, I think it's time to reconsider.
  - madaxe_again 9y ago
    I'm not sure what you're getting at? I'm not explaining climate change, I'm simply explaining that sea level rise isn't uniform. The total volume of water increases both due to melting of on-land ice and thermal expansion of the water column - however it is the case that the resulting increased volume is not evenly distributed, due to the factors I mention above. If you're getting at "crustal thickness" - there are areas of thin or less dense crust where the value of g is lower by a tiny amount - but this tiny amount is enough to cause less water to gather in that area over the vast depth of the water column, as it's essentially uphill to there. https://en.wikipedia.org/wiki/Gravity_of_Earth#Local_topography_and_geology https://en.wikipedia.org/wiki/Gravity_of_Earth#Local_topogra... https://en.wikipedia.org/wiki/Gravity_anomalies_of_Britain_and_Ireland https://en.wikipedia.org/wiki/Gravity_anomalies_of_Britain_a...
    - jschwartzi 9y ago
      In other words the ocean is on a scale which makes it much more complicated than your bathtub.
    - lurquer 9y ago
      Any contiguous fluid surrounding a solid body will form a sphere around the system's center of gravity. Currents, tides, and temperature may cause some deformities, but the variations on the force of gravity due to the the solid earth's nonuniformity in shape and density won't effect the 'level' of the sphere of water that surrounds the center of gravity.
      - sevenfive 9y ago
        > Any contiguous fluid surrounding a solid body will form a sphere around the system's center of gravity. Did you just disprove tides?
        deleted 9y ago
        [deleted]
      - yorwba 9y ago
        Any contiguous fluid in hydrostatic equilibrium will form a shape such that the potential is constant across connected surfaces. If there were a potential difference, this would cause movement on the surface, which means that the fluid won't be in hydrostatic equilibrium anymore. (This is the mechanism that moves the tides: the constantly changing gravity requires a constant movement of the water.) The equilibrium surface is a sphere only if the whole fluid is connected (otherwise fluids on different planets would be required to form a single sphere), and if the potential is spherically symmetric. That symmetry almost never holds exactly, it's just a convenient assumption, e.g. when distances are so large that bodies might as well be point masses. When multiple bodies of comparable mass are involved, e.g. in the solar system, you can't completely ignore their influence. The gravity of sun and moon on the surface of Earth is still strong enough to cause the tides, i.e. differences in water level of several meters. If you measure with sufficient precision, even comparably small objects like tectonic plates can have a non-negligible effect. EDIT: If you disagree, can you explain how my understanding of the physics is wrong?
- filleokus 9y ago
  I'm not really informed about the topic, but I noticed that the Bothnian Bay (the northern bay of the Baltic Sea between Finland and Sweden) is coloured red. The seabed underneath the Botnia Bay has been rising since the end of the ice age (https://en.wikipedia.org/wiki/Bothnian_Bay#Isostatic_rebound https://en.wikipedia.org/wiki/Bothnian_Bay#Isostatic_rebound). Has this not been corrected for in the map (which would explain the red colour), or is it simply a coincidence, and the absolute water level has been rising there as well?
  - yorwba 9y ago
    I'm not sure what kind of "correction" you'd expect? A rising sea floor should in general be associated with a (small) rise in water levels as well, although the depth would still fall. This is due to the gravity of the rocks attracting the water.

madaxe_again 9y ago

Sea level rise isn’t uniform, even on a relatively local scale - while the total volume does inevitably increase, variations such as currents, prevailing winds, standing barometric anomalies and even gravitational variations (thicker crust = shallower ocean) influence relative rise. Here’s a picture illustrating this: http://www.soest.hawaii.edu/coasts/sealevel/MSL_Map_MERGED_Global_IB_RWT_NoGIA_Adjust.png http://www.soest.hawaii.edu/coasts/sealevel/MSL_Map_MERGED_G...

jackhack 9y ago
When an explanation for global cooling/warming/change puts one at odds with Archimedes, I think it's time to reconsider.
- madaxe_again 9y ago
  I'm not sure what you're getting at? I'm not explaining climate change, I'm simply explaining that sea level rise isn't uniform. The total volume of water increases both due to melting of on-land ice and thermal expansion of the water column - however it is the case that the resulting increased volume is not evenly distributed, due to the factors I mention above. If you're getting at "crustal thickness" - there are areas of thin or less dense crust where the value of g is lower by a tiny amount - but this tiny amount is enough to cause less water to gather in that area over the vast depth of the water column, as it's essentially uphill to there. https://en.wikipedia.org/wiki/Gravity_of_Earth#Local_topography_and_geology https://en.wikipedia.org/wiki/Gravity_of_Earth#Local_topogra... https://en.wikipedia.org/wiki/Gravity_anomalies_of_Britain_and_Ireland https://en.wikipedia.org/wiki/Gravity_anomalies_of_Britain_a...
  - jschwartzi 9y ago
    In other words the ocean is on a scale which makes it much more complicated than your bathtub.
  - lurquer 9y ago
    Any contiguous fluid surrounding a solid body will form a sphere around the system's center of gravity. Currents, tides, and temperature may cause some deformities, but the variations on the force of gravity due to the the solid earth's nonuniformity in shape and density won't effect the 'level' of the sphere of water that surrounds the center of gravity.
    - sevenfive 9y ago
      > Any contiguous fluid surrounding a solid body will form a sphere around the system's center of gravity. Did you just disprove tides?
      - deleted 9y ago
        [deleted]
    - yorwba 9y ago
      Any contiguous fluid in hydrostatic equilibrium will form a shape such that the potential is constant across connected surfaces. If there were a potential difference, this would cause movement on the surface, which means that the fluid won't be in hydrostatic equilibrium anymore. (This is the mechanism that moves the tides: the constantly changing gravity requires a constant movement of the water.) The equilibrium surface is a sphere only if the whole fluid is connected (otherwise fluids on different planets would be required to form a single sphere), and if the potential is spherically symmetric. That symmetry almost never holds exactly, it's just a convenient assumption, e.g. when distances are so large that bodies might as well be point masses. When multiple bodies of comparable mass are involved, e.g. in the solar system, you can't completely ignore their influence. The gravity of sun and moon on the surface of Earth is still strong enough to cause the tides, i.e. differences in water level of several meters. If you measure with sufficient precision, even comparably small objects like tectonic plates can have a non-negligible effect. EDIT: If you disagree, can you explain how my understanding of the physics is wrong?
filleokus 9y ago
I'm not really informed about the topic, but I noticed that the Bothnian Bay (the northern bay of the Baltic Sea between Finland and Sweden) is coloured red. The seabed underneath the Botnia Bay has been rising since the end of the ice age (https://en.wikipedia.org/wiki/Bothnian_Bay#Isostatic_rebound https://en.wikipedia.org/wiki/Bothnian_Bay#Isostatic_rebound). Has this not been corrected for in the map (which would explain the red colour), or is it simply a coincidence, and the absolute water level has been rising there as well?
- yorwba 9y ago
  I'm not sure what kind of "correction" you'd expect? A rising sea floor should in general be associated with a (small) rise in water levels as well, although the depth would still fall. This is due to the gravity of the rocks attracting the water.