Why Our Intuition About Sea-Level Rise Is Wrong

Re:Why Our Intuition About Sea-Level Rise Is Wrong by chrischen on Tuesday June 02, 2020 @08:39AM (#23390328)

If the Earth were perfectly round the center of mass would be in the exact center, but if it had lopsided bulge on one side the center of gravity would shift in that direction. The water, being liquid, will want to form a sphere around that new center of mass. That deviation from center means a corresponding increase in water around the surface in that direction. So intuitively, if you think about it this way, 30 something meters deviation from center doesn’t seem too counterintuitive.

[ Parent | on HN ]

Re:Why Our Intuition About Sea-Level Rise Is Wrong by Infernal on Tuesday June 02, 2020 @11:58AM (#23392466)

Is an effect like this similar to the difference between the water level of the Atlantic and Pacific? It never made intuitive sense to me that the Panama Canal for example had to deal with a significant water level difference between the two sides, as the two bodies of water are contiguous at other points on the Earth’s surface.

[ Parent | on HN ]

Re:Why Our Intuition About Sea-Level Rise Is Wrong by rovolo on Tuesday June 02, 2020 @01:46PM (#23393796)

The Panama Canal has locks mainly to raise (by 26m) the water-level over the land. It's less work to flood the area than to dig a giant channel between the oceans.

https://armyengineer.com/history/panama/engineers/How_Canal_...

The average sea level difference on each side is minor in comparison (20cm). Plus, the average sea level isn't constant through the whole ocean. It's variable depending on location due to different salt concentrations (salty water is less dense).

https://oceanservice.noaa.gov/facts/globalsl.html

[ Parent | on HN ]

Re:Why Our Intuition About Sea-Level Rise Is Wrong by Infernal on Tuesday June 02, 2020 @09:16PM (#23398612)

Oh man, thanks for this! I did not realize that it was essentially to hoist the boats over uneven terrain, always assumed the canal was a straight dug channel. Never enough to go search out the answer, but it always tickled the back of my mind when it came up. Thank you!

[ Parent | on HN ]

Re:Why Our Intuition About Sea-Level Rise Is Wrong by njarboe on Tuesday June 02, 2020 @08:31PM (#23398269)

Salty water is more dense.

[ Parent | on HN ]

Re:Why Our Intuition About Sea-Level Rise Is Wrong by rovolo on Wednesday June 03, 2020 @04:24PM (#23408191)

Whoops, of course. It's easier to float in the ocean than in a lake.

[ Parent | on HN ]

Re:Why Our Intuition About Sea-Level Rise Is Wrong by larrik on Tuesday June 02, 2020 @08:41AM (#23390348)

Hard to imagine a floating ice cube having an effect on a sphere with mountains, though.

[ Parent | on HN ]

Re:Why Our Intuition About Sea-Level Rise Is Wrong by chrischen on Tuesday June 02, 2020 @08:47AM (#23390388)

It floats, so it bulges out from the earth, shifting that mass away from perfect center. Given that it’s not liquid, it bulges out non uniformly in one direction and biases center of mass in one specific direction. It also doesn’t matter too much that it’s not particularly high, as it it covers a large area in the general direction. Anything on the northern hemisphere would bias center of mass in that direction.

[ Parent | on HN ]

Re:Why Our Intuition About Sea-Level Rise Is Wrong by chrischen on Tuesday June 02, 2020 @02:19PM (#23394178)

EDIT: I’m not totally sure about the bulging out part of the floating ice is true, but there are also glaciers on land such as over Greenland that would shift the center of mass.

[ Parent | on HN ]