 |
| Fig. 1 Ice Sheet Gravity Lines |
In Fig. 1 the concentric curved lines represent two gravitational dynamics.
One of those dynamics is the pull of the ice sheet generated gravity of Greenland (green lines around Greenland) and the pull of ice sheet generated gravity of Antarctica (black lines around Antarctica).
The other dynamic they represent is what happens as those ice sheets melt or calve into the sea (in which case those lines then represent the moving "hinge point" (see e.g. The Gravity of Sea Level Change).
The hinge point is where there is zero sea level fall (SLF) and sea level rise (SLR), which is kinda like the short time when there is "slack water" between high and low tides.
 |
| Fig. 2 SLC by Ice Sheet gravity |
The hinge point moves away from the land, and the ice sheet on it, as the mass of the ice sheet decreases when melting and calving into the sea.
However, on either side of the moving hinge line there is both SLF and SLR, depending on which side of the line we are talking about (see Fig. 2).
There are positive and negative quantities shown in Fig. 2 in gradients for SLF and SLR.
The negative values, representing SLF are on the side of the hinge line toward the ice sheet, while the positive values, representing SLR, are on the side of the hinge line away from the ice sheet.
The hinge line moves in imperceptible slow motion, much, much slower than normal tides caused by the Moon.
Remember, in the case of ice sheet related hinge lines, we are only talking about ice sheet gravitational effects on the sea level.
 |
| Fig. 3 Global mean SLR |
Which are then adjusted by axial repositioning, the Earth's rotation, and Sun and Moon generated tides.
To further elaborate on that distinction, notice Fig. 3, Fig. 4, and Fig. 5 which were generated by the new beta software.
Those three graphs depict: a) the global mean SLR, an imaginary mathematical
 |
| Fig. 4 Ice Mass Loss Per year |
In Fig. 5 the miles to the hinge point from the center of the ice sheet determines diminishing ice sheet gravity's impact on the sea surface.
 |
| Fig. 5 Hinge Line movement |
It can be envisioned by imagining additional concentric lines expanding out toward each other until they meet.
Before closing, let me remind you of the gentleness of the slope of the negative or the positive SLF and SLR levels.
For example, the "20-25 meter drop" (I use avg. 22.5) in sea level at Greenland where the hinge point is "2000 km" according to Professor Mitrovica, has the following slope (22.5÷2000 = 0.01125).
That is .01125 meters per kilometer (0.03690944882 feet; x 12 = .443 inches) or 0.443 inches per kilometer.
It is not like driving a boat uphill folks.
But, what this serves to show is that public works people literally have a moving target when they consider "adapting" to SLC.
And don't forget that the uncertainty they face is increased the most by the amount of acceleration that governs the amount of, and time for, ice sheet melt to take place as the globe warms (A Timeline of Endangered Sea Ports).
What happens once the ice sheets melt and calve into the sea is academic, when it happens is the projection of mystics and SLC software models (binary mystics).
Acceleration of SLC is happening now, and the variations of SLF and SLR are real.
They must be considered carefully (Geographic Variability of Sea-Level Change, PDF).
So, there is little comfort for public works folk when they hear how consistent the fingerprints of SLC will be (The gravitationally consistent sea-level fingerprint of future terrestrial ice loss).
Real News interview of Dr. McPherson of Nature Bats Last& Dahr Jamail of Truthout: