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Sea Level Rise Pt. 2

Re: Sea Level Rise Pt. 2

Unread postby dohboi » Sun 06 May 2018, 08:31:43

thanks for that, ol.

The weird irony here is that the rich will ultimately be putting themselves in harms way. Even if they are building on slightly higher ground, their predictions about what will be safe for even the relatively near term are almost surely going to be...optimistic.

Sea level rise is likely to happen much more rapidly than most, even those who fully accept climate science and its sea level consequences, expect, especially along the US East Coast.
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Re: Sea Level Rise Pt. 2

Unread postby onlooker » Sun 06 May 2018, 08:45:51

that could definitely be true Dohboi. But, by then won"t other CC consequences already be causing harrowing effects. Such as crop failure. And certainly even more intense hurricanes will have made themselves felt. Would that scare away the rich from the coast? Or maybe extremely expensive or non existant insurance
coverage. One wonders what degree of stubborness some may showcase in ignoring SLR threat given the cumulative evidence.
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Re: Sea Level Rise Pt. 2

Unread postby Tanada » Sun 06 May 2018, 08:59:38

diemos wrote:
Tanada wrote:The rotation of the earth has been calculated to slow slightly if all the ice melts but the biggest implication is the equatorial bulge will distribute much of the melt water to the tropics. This will cause mean sea level rise in for example, Brazil or Indonesia to be about double what it is in Scotland, or Alaska. Now we are talking about 270 feet or so maximum average rise so an extra 20 feet in Brazil will not seem all that important and a 250 foot rise in Scotland will still be devastating.


Well now, this is actually an interesting question with a couple of things going on.

The melt water will distribute itself along the geoid, which is the surface of constant gravitational potential and will result in an even sea level rise around the earth.

But the movement of mass farther from the poles will decrease the rotation rate of the earth and that will cause the size of the bulge at the equator due to the centripetal acceleration to decrease. So some of the bulge will redistribute itself away from the equator and toward the poles.

The statement that most of the water will go to the equator is just geometry and is true even if sea level rise is the same everywhere.

Volume = dh 2 pi r cos(latitude) r dlatitude

where dh is the change in height
2 pi r cos(latitude) is the distance around the earth at that latitude
and r dlatitude is the north-south distance between two latitudes

so if dh is the same everywhere the amount of added water from 0 to 5.7 degrees latitude will be the same as the amount from 64.2 to 90 degrees latitude

And then we get into the question of how lost weight of the ice sheets will cause coastlines to rise leading to an apparent lessening of the sea level rise in some locations.



You also have to factor in the distortion to the gravitational constant of the regions effected. The massive ice sheets of Greenland and even more massive ones of Antarctica are just that, MASS. They extert a distortion effect on the gravitational field of the earth just like that caused by the Rocky Mountains or Tibetan Plateau however as those rock masses take about 300 million years to erode they are very stable influences. The ice mass however can redistribute to the ocean in a period of a millennia or five and when they do the gravitational distortion they cause regionally around Greenland and Antarctica are also redistributed. The well trained physics types have calculated the sea level change in Greenland from removing the mass of the ice sheet without adding the water to the sea total would be about 5 meters, almost enough to locally cancel out the melting effect raising sea level 7 meters. In Antarctica the numbers are even larger because the mass is about four to five times as great.

The sum total of this effect is hard to calculate because as you point out their will be isostatic crustal rebound as the ice is melted away, centripetal redistribution of more water mass to the equator and probably a half dozen other factors I have not mentioned or do not even know exist as a lay person interested in the topic.

Part of the problem is nearly all papers refer to global averages for things like sea level rise (or global warming) but I do not live just on the globe, I live in a specific region and the most important information is how these global averages will work out in my region, to me! I know that is selfish but my sum total gene pool for the last 10 or so generations is mostly in Western Europe and North America with some offshoots in Australia and other places heavily colonized by Western Europe plus a dash of non Europeans according to Ancestry DNA studies. It is not that I don't care what happens to the people in Bangladesh or Venezuela, I just care more about those I feel kinship with. We have a pretty good idea that here around the Great Lakes things will become warmer and wetter while Ireland and Great Britain will lose about half their land surface, maybe more, maybe less, and France will take a big hit as well as Germany but Denmark and Holland will for the most part cease to exist as geographical land regions. Should I feel worse about Bangladesh than I feel about Holland where I actually know some people who were exchange students in my Uni days? Ultimately they are all going to suffer because of where they live and the species as a whole would be infinitely better off if they were to move NOW to high ground taking all permanent structures with them. The low lands could still be maintained as crop and grazing land until they are lost, but relocate the people and buildings now! Of course people will not admit the likely outcome of the scientific consensus so nothing will be done. If I lived in Hamburg Germany or Boston Massachusetts I would probably resist the idea of relocating just as much as they do. KJ likes to put up a picture of future NYC with a huge dike surrounding it. Maybe that will happen, but who is going to pay for it? The cost of moving those people to higher ground and even physically moving the existing buildings deemed worth saving is incredibly less than building a 75 meter high flood wall and maintaining it indefinitely into the future.
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Re: Sea Level Rise Pt. 2

Unread postby dohboi » Sat 19 May 2018, 14:09:35

slr accelerated to 4.6 mm/year after 2010:

https://robertscribbler.com/2018/05/15/ ... fter-2010/
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Re: Sea Level Rise Pt. 2

Unread postby dohboi » Sat 09 Jun 2018, 10:47:22

2017 Broke Records for Number of Flooded Days on U.S. Coasts

https://www.ecowatch.com/coastal-floodi ... 14503.html

... coastal high tide flooding in the U.S. will be up to 60 percent more frequent in 2018 than it was 20 years ago...
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