Monday, May 23, 2022

Seaports With Sea Level Change - 22

Port of NY/NJ
I. Ice Mass Loss

A study not too long ago focused on ice-mass lost on the Southern Ocean continent of Antarctica:

"The mass loss is dominated by enhanced glacier flow in areas closest to warm, salty, subsurface circumpolar deep water, including East Antarctica, which has been a major contributor over the entire period. The same sectors are likely to dominate sea-level rise from Antarctica in decades to come as enhanced polar westerlies push more circumpolar deep water toward the glaciers."

(Four decades of Antarctic Ice Sheet mass balance from 1979–2017). Antarctica has been a "major contributor" to ice-mass loss.

That also has a major contribution to sea level change (SLC) because glacial ice entering the ocean from a land mass causes the sea level to change.

II. Ice-Mass Loss Impact On The World's Seaports

The video at the end of this post features MIT professor Dr. Mitrovica, who explains that sea level change is not like bath tub waterline change, which tends toward staying level all along its waterline.

To the contrary, sea level rises and falls unevenly, due to tides, but also due to the fact that the Cryosphere (ice on land) is melting into the ocean.

As the Cryosphere melts, the sea level falls (gets lower) near large ice sheets on land-masses, but sea level rises at other areas far away from those land-masses. 

Regular readers know that this has been discussed for years on Dredd Blog (e.g. Will This Float Your Boat?, 2011; cf. video below).

In Dredd Blog posts, as time went on, Seaports were featured as the locations that would have the greatest impact on civilization as sea level change had an impact on them (Why Sea Level Rise May Be The Greatest Threat To Civilization, 2015).

III. Shifting Focus: From Greenland To Antarctica

Traditionally Greenland has been seen as the location to watch in terms of ice-mass loss and the impact of sea level change.

But in recent years the focus is changing as the quote above in Section I indicates.

Dr. Rignot of NASA, the lead author in the published paper quoted above, informs us that Antarctica is "likely to dominate sea-level rise ... in decades to come".

A recent Dredd Blog post illustrates graphically why that is so:

"... we might as well address the issue of red and blue states.

Today's appendices (Filled In, Not Filled In) show the states of water temperatures that are melting the largest desert on Earth.

The "Filled In" appendix shows, in red, the warmer-than-ice deep waters along the grounding lines of Antarctica's tidewater glaciers.

The "Filled In" appendix also shows, in blue, the colder-than-water ice along the grounding lines of Antarctica's tidewater glaciers.

The "Not Filled In" appendix lines simply show tidewater temperatures along with the melt temperatures of glacial ice in the ambient tidewater.

These graphics in the appendices exhibit the main reason for the change in ice sheets (it isn't surface melt nor calving) as pointed out by Dr. Eric Rignot in the second video below ..."

(Antarctica 2.0 - 14). The graphs show why seaports are the prime targets as the source for sea level change's greatest impact on civilization.

IV. On To The Seaports

We know how important seaports are:

"By volume, more than 95 percent of U.S. international trade moves through the nation's ports and harbors, with about 50 percent of these goods being hazardous materials."

(NOAA PORTS, emphasis added; cf. Ports & Harbors). The appendices in this series have time and again shown that sea level change is happening at seaports around the globe. 

The appendices to today's post are linked-to in the following menu:

(HTML) Single
Coastline Countries
(HTML) Multi
Coastline Countries
Coastline Graphs
Appendix: A-CAppendix: A-CAppendix: A-C
Appendix: D-GAppendix: D-GAppendix: D-G
Appendix: H-LAppendix: H-LAppendix: H-L
Appendix: M-OAppendix: M-OAppendix: M-O
Appendix: P-TAppendix: P-TAppendix: P-T
Appendix: U-ZAppendix: U-ZAppendix: U-Z

The seaport graphs and HTML tables in today's appendices only cover the past 5 decades (~50 years).

Thus, there aren't as many graphs and tables as in the previous posts in this series that featured centuries-long coverage, that is coverage from 1800-2021 (Seaports With Sea Level Change - 20).

But in any case, seaport authorities begin sending in their data to the Permanent Service for Mean Sea Level (PSMSL) at different times, and they stop sending in their data at different times too.

So, the graph and HTML table time-frames can vary from port to port and from time to time.

V. Closing Comments

Some time ago the question arose in this series concerning whether or not aircraft could supply what seaport trade now supplies, should seaports become impaired:

"In Fig. 1 the largest container ship is pictured, the link at Fig. 2 goes to a page that has descriptions of the 100 largest of such vessels.

Note that the cargo capacity of that container ship is 19,224 TEU up to 193,000 gross tons (386,000,000 lbs.).

By comparison, the largest cargo aircraft, the Lockheed C-5 Galaxy, has a payload of 270,000 lbs. (see Fig. 3).

Which means it would take (386,000,000 lbs. ÷ 270,000 lbs = 1430) 1,430 C-5 Galaxy aircraft to match the load of one cargo ship.

There aren't that many C-5 aircraft, and there are hundreds of cargo ships.

You get the picture."

(Weekend Rebel Science Excursion - 44). Recently the media has attempted to poo poo the reality of the importance of seaport trade with a story of a military aircraft bringing cargo from across the ocean (Baby formula arrives on US military aircraft). 

The old saying "That dog won't hunt" comes to mind.

The previous post in this series is here.


  1. In the first video, Dr. Mitrovica criticizes "the bathtub model" of the ocean. There are several other reasons the bathtub model is a fantasy ... e.g. Panama canal: "Sea level is about 20 cm higher on the Pacific side than the Atlantic due to the water being less dense on the Pacific side, on average, and due to the prevailing weather and ocean conditions. Such sea level differences are common across many short sections of land dividing ocean basins."(

  2. "A new survey of expert opinion suggests 21st century sea level rise might be higher than the latest UN climate report projects. More than two thirds of the researchers interviewed for the study said higher and faster rises are possible – implying the report’s estimates could be too conservative." (Carbon Brief)