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Oddly, sea level will probably go down this far north. Earth is spinning, drawing water to the equator. More mass, more gravity pulling water to the equator, al

by jfoutz 10y ago

Oddly, sea level will probably go down this far north. Earth is spinning, drawing water to the equator. More mass, more gravity pulling water to the equator, along with less mass at the poles to offset. But, yeah, I don't think I'd buy anything by the water either. edit So, I'm wrong, Northern California isn't far enough north. it's a real effect. You're all underestimating the mass of 100,000 cubic miles of ice. [1] http://science.sciencemag.org/content/323/5915/753 http://science.sciencemag.org/content/323/5915/753 [2] http://www.nature.com/nature/journal/v409/n6823/abs/4091026a0.html http://www.nature.com/nature/journal/v409/n6823/abs/4091026a... reply

peterwaller 10y ago
> Oddly, sea level will probably go down this far north. Earth is spinning, drawing water to the equator. More mass, more gravity pulling water to the equator, along with less mass at the poles to offset. Can you provide a reference or show some workings which demonstrate that statement to be true? I've not heard this before, and it's not obvious that it should be true.
- jfoutz 10y ago
  Here's one. http://harvardmagazine.com/2010/05/gravity-of-glacial-melt http://harvardmagazine.com/2010/05/gravity-of-glacial-melt Wikipedia eqitorial bulge has some info as well.
  - rripken 10y ago
    I'm unconvinced. I don't see anything in the harvardmagazine article that suggests sea level fall in Northern California. The wikipedia page explains that equatorial bulge has been decreasing. I'd expect ice-melt to add mass along the equator and further slow rotation which should further reduce equatorial bulge. I'm not saying you are wrong its just that your references don't explain your contention in a way that I can make sense of.
    - jfoutz 10y ago
      I'm wrong. edited the main comment with more references.
- calebsurfs 10y ago
  California isn't an area where sea level will go down, ironically it will go down near Greenland and Antarctica due to less gravity from ice sheets. There are some nice maps towards the bottom of this article: http://onlinelibrary.wiley.com/doi/10.1029/2012GL053000/full http://onlinelibrary.wiley.com/doi/10.1029/2012GL053000/full Since Florida is near the equator, facing the same ocean as Greenland, and has subsiding land, it will likely experience more effects of sea level rise.
- mr_overalls 10y ago
  Jerry Mitrovica is a Harvard geophysicist who's at the forefront of variations in sea level rise. http://nautil.us/issue/33/attraction/why-our-intuition-about-sea_level-rise-is-wrong http://nautil.us/issue/33/attraction/why-our-intuition-about...
recursive 10y ago
More mass? From where? I don't think the mass of polar ice caps significantly pulls water toward the poles. Water follows gravity, which points approximately toward the center of the earth everywhere, with very minor deviations for the centrifuge effects of rotation.
- nkrisc 10y ago
  I think, and I'm not convinced here, that they're considering the distribution of mass to be the key factor not total mass as that is (as far as we're concerned here) fixed. Again, just speculating.
- URSpider94 10y ago
  Your intuition is incorrect, the impact of ice sheets on local sea level due to gravitational attraction is significant (tens of feet). http://sealevelstudy.org/sea-change-science/whats-in-a-number/attractive-ice-sheets http://sealevelstudy.org/sea-change-science/whats-in-a-numbe...
IncRnd 10y ago
I'm not sure that your reasoning makes sense.
deelowe 10y ago
> Oddly, sea level will probably go down this far north. Earth is spinning, drawing water to the equator. More mass, more gravity pulling water to the equator, along with less mass at the poles to offset. Uhh... Is this true? Doesn't seem right to me...
- AnimalMuppet 10y ago
  There is a small effect in that direction - the earth's spin makes the sea level a few feet higher at the equator than it would be if the earth were not rotating. But the bit you quoted implies something more of a runaway effect. I'm pretty sure that won't happen - there's not enough mass in water compared to the total mass of the earth. In fact, I'm pretty sure that adding more water to the oceans will raise sea levels even at the poles, despite the rotation of the earth. It's pretty easy to calculate the acceleration due to rotation at the equator. It's a = omega^2 x R, where omega is (2 pi) / (24 * 60 * 60) seconds = 7.27e-5 / seconds, and R is the radius of the earth = 6.371e6 meters. The acceleration due to rotation is then a = 0.0337 m/s^2. Compare with 9.8 m/s^2 for gravity. That's 0.3% of gravitational acceleration. That's... not very much.
rripken 10y ago
Can you explain in more detail how melting ice would cause sea level fall in Northern California? Are you saying this would happen because of changes to the speed of rotation? Change of pole location? A change to earth's shape?
- deleted 10y ago
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by jfoutz 10y ago

peterwaller 10y ago

> Oddly, sea level will probably go down this far north. Earth is spinning, drawing water to the equator. More mass, more gravity pulling water to the equator, along with less mass at the poles to offset. Can you provide a reference or show some workings which demonstrate that statement to be true? I've not heard this before, and it's not obvious that it should be true.

jfoutz 10y ago
Here's one. http://harvardmagazine.com/2010/05/gravity-of-glacial-melt http://harvardmagazine.com/2010/05/gravity-of-glacial-melt Wikipedia eqitorial bulge has some info as well.
- rripken 10y ago
  I'm unconvinced. I don't see anything in the harvardmagazine article that suggests sea level fall in Northern California. The wikipedia page explains that equatorial bulge has been decreasing. I'd expect ice-melt to add mass along the equator and further slow rotation which should further reduce equatorial bulge. I'm not saying you are wrong its just that your references don't explain your contention in a way that I can make sense of.
  - jfoutz 10y ago
    I'm wrong. edited the main comment with more references.
calebsurfs 10y ago
California isn't an area where sea level will go down, ironically it will go down near Greenland and Antarctica due to less gravity from ice sheets. There are some nice maps towards the bottom of this article: http://onlinelibrary.wiley.com/doi/10.1029/2012GL053000/full http://onlinelibrary.wiley.com/doi/10.1029/2012GL053000/full Since Florida is near the equator, facing the same ocean as Greenland, and has subsiding land, it will likely experience more effects of sea level rise.
mr_overalls 10y ago
Jerry Mitrovica is a Harvard geophysicist who's at the forefront of variations in sea level rise. http://nautil.us/issue/33/attraction/why-our-intuition-about-sea_level-rise-is-wrong http://nautil.us/issue/33/attraction/why-our-intuition-about...

recursive 10y ago

More mass? From where? I don't think the mass of polar ice caps significantly pulls water toward the poles. Water follows gravity, which points approximately toward the center of the earth everywhere, with very minor deviations for the centrifuge effects of rotation.

nkrisc 10y ago
I think, and I'm not convinced here, that they're considering the distribution of mass to be the key factor not total mass as that is (as far as we're concerned here) fixed. Again, just speculating.
URSpider94 10y ago
Your intuition is incorrect, the impact of ice sheets on local sea level due to gravitational attraction is significant (tens of feet). http://sealevelstudy.org/sea-change-science/whats-in-a-number/attractive-ice-sheets http://sealevelstudy.org/sea-change-science/whats-in-a-numbe...

IncRnd 10y ago

I'm not sure that your reasoning makes sense.

deelowe 10y ago

AnimalMuppet 10y ago
There is a small effect in that direction - the earth's spin makes the sea level a few feet higher at the equator than it would be if the earth were not rotating. But the bit you quoted implies something more of a runaway effect. I'm pretty sure that won't happen - there's not enough mass in water compared to the total mass of the earth. In fact, I'm pretty sure that adding more water to the oceans will raise sea levels even at the poles, despite the rotation of the earth. It's pretty easy to calculate the acceleration due to rotation at the equator. It's a = omega^2 x R, where omega is (2 pi) / (24 * 60 * 60) seconds = 7.27e-5 / seconds, and R is the radius of the earth = 6.371e6 meters. The acceleration due to rotation is then a = 0.0337 m/s^2. Compare with 9.8 m/s^2 for gravity. That's 0.3% of gravitational acceleration. That's... not very much.

rripken 10y ago

Can you explain in more detail how melting ice would cause sea level fall in Northern California? Are you saying this would happen because of changes to the speed of rotation? Change of pole location? A change to earth's shape?

deleted 10y ago
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