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| Sooner than later? |
I. Deja Vu
I have written about one of the most often used phrases in the Warming Commentariat literature.
That phrase is "worse than previously thought."
Today's post continues the Dredd Blog tradition of highlighting that practice.
In a recent article title the phrase has become a paraphrase "New elevation data triple estimates of global vulnerability to sea-level rise and coastal flooding", or to put it another way:
"SRTM models the elevation of upper surfaces and not bare earth terrain. It thus suffers from large error with a positive bias when used to represent terrain elevations. This is especially true in densely vegetated and in densely populated areas. Mean error in SRTM’s 1–20 m elevation band is 3.7 m in the US and 2.5 m in Australia when using DEMs from airborne lidar as ground truth. Space borne lidar from NASA’s ICESat satellite, a sparser, noisier and less reliable source of ground truth than airborne lidar, indicates SRTM has a global mean bias of 1.9 m in the same band. This degree of error leads to large under-estimates of ECWL exposure, and exceeds projected sea-level rise this century under almost any scenario."(Nature Communications, emphasis added). One should question or analyze what this means for seaports, a critical organ of international trade, and by extension what it means for civilization as we know it (The Extinction of Robust Sea Ports, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11; Seaports With Sea Level Change, 2, 3, 4, 5, 6).
II. What Does It Mean For World Seaports?
Sea level change (SLC) in the form of sea level rise (SLR) is more widespread and more of a threat than sea level fall (SLF) is, because SLF only takes place "near" (0 km - 2,000 km distance) large ice sheets (e.g. Greenland and Antarctica) and "near" large land glacier areas (e.g. Glacier Bay Alaska and "Third Pole" Himalayas).
"Pseudo SLC" (land surface elevation rise and fall) is not SLC, it is land-surface elevation change (LSC).
However, it too can have and impact on seaports and should, where relevant, be factored in.
According to the Nature Communications paper linked to above in Section I, millions of additional people are exposed to SLC and coastal flooding by the new "worse than previously thought" estimates.
Seaports are also at additional risk, because they experience SLC at two critical points: high tide and low tide (daily Sun & moon caused SLC) in the form of higher and higher and/or lower and lower water levels (as Cryosphere melt caused SLC impacts them).
Further, in our era of SLC, in general the age of the seaport is also a factor.
That is because there will have been more SLC at older sites over time than at those more recently constructed seaports.
Thus, one size does not fit all, nor does SLC take place equally everywhere.
So each location must determine its own local SLC by careful analysis (The Gravity of Sea Level Change, 2, 3, 4, 5; NASA Busts The Ghost; The Ghost-Water Constant, 2, 3, 4, 5, 6, 7, 8, 9; Proof of Concept, 2, 3, 4, 5, 6, 7, 8, 9, 10).
III. Closing Comments
This means that even more millions will be impacted as seaports, which furnish them with goods from far across the oceans, are damaged or destroyed by SLC and coastal flooding.
The previous post in this series is here.