Friday, August 14, 2015

Weekend Rebel Science Excursion - 48

Fig. 1 Grasping the SLC concept
I. Background

It is Friday, so let's rebel.


Regular readers know that in recent Dredd Blog posts I have tended to consider the dynamics of sea level change (SLC).

Regular readers also know that SLC is composed of both sea level rise (SLR) as well as sea level fall (SLF).

If you want to read the latest developments in this ongoing narrative, a brief historical timeline of the cycle of recent SLC (past century) has been posted on Ecocosmology Blog (A Timeline of Endangered Sea Ports).

II. Today's Goal - Simplification

Today, in this post I want to show that the technical calculation of SLC at the location where you live and work is, among other things, a function of observing tides.

Tidal charts are quite accurate, because the Moon, the Sun, and the Earth are stable in terms of the gravitational, rotational, and orbital astrophysics involved in calculating tides.

There are many places to look up tidal times and tidal intensities that apply to your particular location (e.g. Salt Water Tides, NOAA - Tides), assuming that you are near enough to the ocean to care, or that you realize your country's future will be impacted by these dynamics.

High and low tides are caused by lunar and solar gravity "pulling" on the ocean (The Gravity of Sea Level Change).

Both of those gravities are very stable and reliable forces, even though they are constantly changing sea levels.

They are well understood, busily changing regional sea levels at any given time of day or night.

Since SLC is a similar, albeit slower dynamic, why reinvent the wheel?

III. Calculating The Impact of Global Warming Induced SLC

Let's continue with the goal of simplification (complications are discussed in Section IV below).

After we look up the relevant tide information (high, slack, low) for a specific date, time,
Fig. 2 SLC regional impact
and location, then we can add or subtract ongoing SLC values.

In this case I mean SLC values that are caused by ongoing global warming induced ice sheet melt and disintegration (The Question Is: How Much Acceleration Is Involved In SLR? - 8).

But first, we must consider the "moving parts" part of this "simple process."

One reason for that is because SLC is happening slowly, happening from two major sources, and the impact that each has on a given location varies with time.

Not only that, they both have an SLR and SLF impact that is constantly changing as the ice sheets melt, and once again, SLR or SLF and how much, depends on our location (lat. & long.) on the globe (The Agnotology of Sea Level Rise Via Ice Melt).

The location where I am may be having an SLF phenomenon at the same time your location may be having an SLR phenomenon, so we must know which situation (SLR or SLF?) apples to our location before we can apply Fig. 2 values as follows:
1) SLC (SLR or SLF) computation is the addition or subtraction of a percentage to, or from, a tidal value derived from a tidal chart.

2) The addition to, or the subtraction from, existing high or low tide values derived from the tidal chart, will assist by conforming the past realities to the new observations of SLC.

3) The range of percentages for SLR is 0% to 100% (Fig. 2).

4) The range of percentages for SLF is -0% to -100% (Fig. 2).
Now that we have done the easy part, let's consider the difficult part.

IV. Some Complications Can't Be Avoided

Fig. 3 Greenland induced SLC
First, notice the SLC graphic depictions in Fig. 3 and Fig. 4.

They are individualized concepts isolated, for simplicity, to one particular ice sheet.

Fig. 3 depicts the Greenland ice sheet induced SLC, after all of its ice has melted or otherwise disintegrated to end up in the northern seas.

On the other hand, Fig. 4 depicts the Antarctica ice sheet induced SLC, after all of its
Fig. 4 Antarctica induced SLC
ice has melted or otherwise disintegrated to end up in the southern seas.

Fig. 3 and Fig. 4 are fine and helpful for contemplating the barest nature of the two ice sheets, and for contemplating what SLC associated with them will look like in the future, however, they are both fanciful notions in other fundamental respects.

Still, those two depictions are fine for an elementary or preliminary contemplation of SLC.

The distortion involved with using them individually is that both of those ice sheets are melting at the same time, so their SLR and SLF impacts blend together (excluding them individually from anything other than elementary or preliminary contemplation).

Furthermore, each ice sheet impacts the other's SLR and SLF to some degree, and the degree of each ice sheet's impact on the other is constantly changing.

That constant change is due to the constant, but sometimes almost imperceptible, ice sheet melt and disintegration.

Take a look at two graphs here at the heading "A Sea Level Change Software Model".

Currently, as those graphs show, Greenland is the prime contributor of ice sheet melt and disintegration, however, Antarctica will overcome that to become the prime contributor of ice sheet melt and disintegration in the future.

V. Driving Public Works and Port Authority Officials Crazy

When port authority officials and public works departments know exactly what is going on, they move at the speed of snails (New Climate Catastrophe Policy: Triage - 12).

When they contemplate a project, not knowing if the SLC they face is going to be SLR or SLF or both at different times, they will tend to move at the speed of snails going backwards.

VI. Conclusion

Civilization is facing a problem that is a shape-shifter, a liquid terminator, and something never before faced.

And, it is a problem that will only get worse with time (Sea Level Study, Princeton, Guardian, Vice News).

As President Obama said recently: "There is such a thing as too late when it comes to Climate Change."

Have a good weekend anyway.

Heart of Gold, by Neil Young (acoustic version):


  1. Great job on this Dredd. Really spelling it out. I'm glad you see the differential equation inherent in this research and i appreciate its complexity.


  2. I want to look up my fav. sea port.

    I am anxious.

  3. And if Port Authorities are moving slowly, at least they're paying /some/ attention to SLC. Not so much those planning on building nuclear reactors along various coastlines.