|Fig. 1 Comparison: Hansen 2015 / IPCC 5th|
The Hansen 2015 paper hypothesized that a 10 ft global mean sea level rise (SLR) could (not would) take place within 35 years, i.e. by the year 2050 (A Paper From Hansen et al. Is Now Open For Discussion).
That hypothesis depends on what they call a "10 year doubling" phenomenon in ice
|Fig. 2 Model uses same history|
I have abandoned the "doubling" logic in favor of the acceleration intensity concept, which uses the tide gauge history as a foundation, then apply both low intensity IPCC acceleration as well as high intensity Hansen 2015 acceleration to the characteristics of the historical record.
There are four reasons for so doing: 1) the Dredd Blog model is based on individual SLR at individual Permanent Service for Mean Sea Level (PSMSL) tide gauge stations around the world, 2) the low and high hypotheses are combined, 3) only two graphs are needed to show PSMSL sea level change (SLC) in RLR meters (Fig. 1), and actual change in millimeters (Fig. 2), and 4) the global mean average is not used any more (except for reference when that would help).
Prior to these changes, the reader had to figure out the quantity of change by bothersome calculations that are now done by the software.
From now on these two graphs will be used for each PSMSL tide gauge station when those sites are discussed (the history portion is exactly the same for high and low, then they split into two streams, two lines, red is Hansen 2015, black is IPCC 5th Assessment).
The year that the tide gauge came on line will tend to have a different sea level than one which came on line in a different year.
PSMSL techniques are designed to have a relative dynamic which normalizes the values (compare the beginning point of the sea level RLR meters with the change
Note that the change calculation graphs ("IPCC change", "Hansen change") begin at zero, but the PSMSL sea level value graphs do not.
Sea level can be different even if two or more tide gauge stations came on line at the exact same time depending on where those tide gauge stations are located, but that is not likely.
Another thing to remember is that what matters is the ramifications of SLC on civilization, especially the impact on sea ports (Why Sea Level Rise May Be The Greatest Threat To Civilization, 2, 3, 4, 5).
For example, the strongest hurricane ever recorded did not harm the busiest sea port in Mexico, but SLR eventually will (The Extinction of Manzanillo).
The same cannot be said about SLC, because it is attacking all the sea ports at the same time so debilitation will be universal at some point in time (Weekend Rebel Science Excursion - 44, Greenland & Antarctica Invade The United States, The 1% May Face The Wrath of Sea Level Rise First, Why The Military Can't Defend Against The Invasion).
If SLC was a conscious national enemy, rather that a product of burning fossil fuels fostered on civilization by Oil-Qaeda, that conscious enemy would be delighted because a surprise attack is an advantage in such situations.
Concerning the Hansen model mentioned in this post, one of the several co-authors of their paper linked to above is featured in the video below.
These are serious scientists whom we have been ignoring at our peril for far too long (The Extinction of Washington, D.C.).
The next post in this series is here, the previous post in this series is here.
An up-to-date discussion of ice shelves vs. ice sheets, using the nomenclature of ice stream science by Dr. Rignot:
15:29 when the ice shelf "Larsen A" collapsed the entire glacier's flow speed toward the sea increased ...
18:50 "Larsen B" ice shelf collapse caused the same thing ... the entire glacier's flow accelerated toward the sea ...
19:30 when the ice shelf goes away so does the restraint on the glacier, and they then move faster, 8 times faster, toward the sea
27:15 the East Antarctica Totten Glacier basin contains about as much ice as all of Western Antarctica, and it is destabilizing
30:30 the condition of the ice shelf controls what happens to the ice sheet