|Make Others Do It|
This is an update to the Seaports With Sea Level Change series.
Two factors necessitated the update.
The first is that the PMSL updated their databases, and the second is that I added a couple of Cryosphere locations (Norway and "The Third Pole").
This will have an impact on seaport data for seaports in or near WOD Zones within 2,000 kilometers of Norway glaciers or The Third Pole area (Himalayas).
Think of The Third Pole area as north of India but near enough to the coast of India to have either sea level rise (SLR) or sea level fall (SLF) impacts on ports in that area.
Third Pole data will change only the analysis of that area of the Cryosphere where it is causing SLF in areas within 2,000 km of seaports (e.g. China or India).
The seaport data detailing the characteristics of each seaport from World Ports by Country is unchanged, but in some cases the PSMSL sea level change (SLC) updates may change the SLF or SLR values at some seaports and tide gauge stations (Seaports With Sea Level Change, 2, 3, 4, 5).
II. The Origins and Dynamics of Modern SLC
It seems that many people are still unaware of the non-intuitive way in which SLC takes place.
I would venture to say that regular Dredd Blog readers do not have that problem, because the nature of SLC is discussed often here.
It starts with the work of Woodward (1888) which has been enhanced:
"It has been known for over a century that the melting of individual ice sheets and glaciers drives distinct geographic patterns, or fingerprints, of sea level change, and recent studies have highlighted the implications of this variability for hazard assessment and inferences of meltwater sources."(Mitrovica et al. 2018, emphasis added). Mitrovica et al. (2018) used advanced analytic techniques to enhance that understanding (cf. The Bathtub Model Doesn't Hold Water).
The Woodward (1888) hypothesis that SLF takes place because the seawater is relocated as the ice sheet gravity decreases in power has been confirmed by NASA (NASA Busts The Ghost).
Basically, it goes like this: during the previous Ice Age a Cryosphere was formed when great masses of ice froze in place on many of the Earth's land masses.
Due to the gravity created by the mass of those great ice sheets and glaciers that had formed, seawater was pulled toward the coasts of those land masses upon which the ice masses came to rest.
When the Industrial Revolution began, circa 1750, green house gases (GHG) began to be emitted into the atmosphere as the use of fossil fuels increased.
The GHG began to trap more and more heat (infrared radiation) in the atmosphere, and the global temperatures began to rise and melt the ice.
According to one of the largest oil companies, fossil fuels were the cause of the melt (Humble Oil-Qaeda).
At first they bragged about it, but after a couple of decades they began to backtrack from their admission and to deceive the public about the warming that was taking place.
In effect they became an epi-government, pulling the strings of government from behind the scenes (The Authoritarianism of Climate Change, The Harm Oil-Qaeda Has Done).
As a result of the subterfuge they instituted, and its impact on the scientific community (which still exists to this day) the notion of global warming caused by fossil fuels faded into the shadows (A Falsified Oil-Qaeda Hypothesis Spreads).
Nevertheless, the general nature of SLC is now well-known by those who focus on it:
"A standard global calculation based on the assumption of uniform, rapid melting from the Greenland Ice Sheet (GIS) equivalent in volume to a GMSL rise of 1 mm yr-1 highlights the physical effects that contribute to sea level fingerprints (see Fig. S1 in the online supplemental material at the Journals Online website: https://doi.org/ 10.1175/JCLI-D-17-0465.s1.). Within a zone that extends ~2000 km from an ice sheet, sea level will fall [a few exceptions - see appendices] as a consequence of both the decreased gravitational pull of the diminished ice sheet and the elastic uplift of the crust in response to the ice unloading. At the edges of Greenland, this sea level fall can reach ~10 mm yr-1, an order of magnitude larger than (and of opposite sign to) the equivalent GMSL rise. The predicted sea level change generally increases at progressively greater distance from the ice sheet, with maximum values of ~1.4 mm yr-1 in regions far from the melting ice."(Mitrovica et al. 2018, emphasis added). The rule of thumb for SLC is that SLF takes place near ice sheets as they melt because the released seawater is relocated to another location where it causes SLR (along with the melted ice water that is also relocated).
Today's appendices show substantial SLC variation at seaports around the globe.
Links to the source databases, from which the recorded in situ measurements originate, emphasize the difficulty in responding to a non-uniform global SLC.
When responding to SLC, one port authority can have an opposite set of issues to confront compared to another port authority in another country.
|The Cryosphere (areas within the Cyan colored lines)|
SLF Seaport locations (red squares)
|Appendix: A - C||Appendix: A - C|
|Appendix: D - G||Appendix: D - G|
|Appendix: H - L||Appendix: H - L|
|Appendix: M - O||Appendix: M - O|
|Appendix: P - T||Appendix: P - T|
|Appendix: U - Z||Appendix: U -Z|
IV. Closing Comments
The "Seaports With Sea Level Change" series has been improved with this update.
The IPCC has issued a new report: "IPCC Special Report on the Ocean and Cryosphere in a Changing Climate" (SROCC, PDF).
The next post in this series is here, the previous post in this series is here.
Dr. Jerry Mitrovica
at ~31:14: "By taking the [global] average you're assuming something, and you're assuming it implicitly. You're assuming what we call the bathtub model." - Dr. Mitrovica