The mayor of Honolulu should not believe in sea level speculations

As reported in,

this week,

Honolulu Mayor Kirk Caldwell signed a directive

ordering all city agencies to take action to prevent sea level rise.

The directive calls for agencies to treat climate change as an “urgent matter” and to develop land use policies, building codes and hazard mitigation actions to prevent the worst impacts of rising seas.

The action follows the release of a report

from the Honolulu Climate Change Commission, led by the University of Hawaii, which said that Oahu is the most vulnerable Hawaiian island and could see nearly 4,000 structures and 18 miles of coastal road be destroyed if oceans rose three feet by mid-century.

The directive also calls for agencies to use the findings of the report in all planning and capital improvement decisions, and for proposed revisions to shoreline rules and regulations to incorporate sea level rise.

Problem is that rather than the “real” sea level rise, the mayor of Honolulu is considering the “virtual” one, living only in computer games and pure speculations, carried out even without a computer.

The sea levels are measured for real, with good method and accuracy, in the long-term tide gauge locations.

In Honolulu, there is one of such tide gauges.

As shown in Figure 1 (image is from, the mean sea level trend is +1.48 mm/year with a 95% confidence interval of ±0.21 mm/year, based on monthly mean sea level data from 1905/1 to 2018/5. That is equivalent to a change of 0.58 feet in 100 years. That compares very badly to the three feet by mid-century, i.e. 3 feet in 32 years.

More than three feet, the sea level rise in Honolulu will be likely 0.1856 feet by mid-century.

Also, it may take more likely 517 years, rather than 32 years, to make a 3 feet sea level rise.

figure 1.pngFigure 1 – MSL in Honolulu with linear and parabolic fittings. Image from MSL updated to May 2018.

Is there any sign that this stable pattern, demonstrated since the start of the 20th century, is going to change?

If we compute the acceleration, this parameter is -0.00535 ±0.01443 mm/yr², i.e. it is small, of the order of the micrometers per year squared, and it is eventually negative, rather than positive.

So, possibly, the sea level rise in Honolulu by mid-century will be very likely even less than 0.1856 feet.

Is the trend of Honolulu an exception? Not at all. It is the same everywhere the sea levels have been measured by tide gauges over time windows long enough to understand natural variability.

If we look at the other four long-term tide gauges of Oceania, Fremantle and Sydney in Australia, Auckland and Dunedin in New Zealand, the average regional relative rate of rise is +1.306 mm/yr., and the average regional acceleration is +0.00490 mm/yr2.

Things are not going better for climate alarmism moving to the East coast of Asia, where Japan has five long-term tide gauges, Oshoro, Wajima, Hosojima and Tonoura affected to a lesser extent by crustal movement, and Aburatsubo, that is affected by crustal movement.

The average regional relative rate of rise is +0.08 mm/yr., and the average regional acceleration is -0.01105 mm/yr2 without Aburatsubo.

With Aburatsubo included, the average regional relative rate of rise is +0.79 mm/yr., and the average regional acceleration is -0.01016 mm/yr2.

Opposite to their colleagues in the Western world directed by “fake news”, the Japanese meteorological office,

is still free to write the truth

A trend of sea level rise has been observed in Japanese coastal areas since the 1980s, but no clear long-term trend of rise is seen for the period from 1906 to 2017.

So, basically, not only no sea level acceleration, but not even sea level rise in Japan, if the tide gauges affected by crustal movement are excluded.

Things are also going bad for alarmism moving to the West coast of North America.

In the 20 long term stations along the West Coast of North America, Ketchikan, AK, USA; Sitka, AK, USA; Juneau, AK, USA; Unalaska, AK, USA; Prince Rupert, Canada; Point Atkinson, Canada; Vancouver, Canada; Victoria, Canada; Tofino, Canada; Friday Harbor, WA, USA; Seattle, WA, USA; Neah Bay, WA, USA; Astoria, OR, USA; Crescent City, CA, USA; San Francisco, CA, USA; Santa Monica, CA, USA; Los Angeles, CA, USA; La Jolla, CA, USA; San Diego, CA, USA; Balboa, Panama, the regional average relative rate of rise is -0.38 mm/yr., and the regional average acceleration is +0.0012 mm/yr2.

The Pacific Ocean covers about 46% of Earth’s water surface, and definitively much more than 50% of the Earth’s water volume.

Thinking even more global, despite the progress of the “adjustocene” also in data bases of tide gauges, even more widespread data sets do not show accelerations larger than a few micrometers per year squared.

If there is something sure in the science of global warming and sea level rise, is that no sensible sea level acceleration has been detected so far in the long-term tide gauges of the world, those that may permit to understand if some short-term movement is unprecedented or, it occurred already 60 years before.

Sometimes, the sea level rises because the land is sinking, as it is clearly the case of the most part of the Hawaii Island (and California).

As also written in touristic guides:

the explanation of the sea level rise in Honolulu is the “geologic circle of life” beyond the Hawaiian “hot spot” more than the evil carbon dioxide emission.

The Hawaiian Islands are situated near the middle of the “Pacific Plate” on top of a “hot spot.”. The constant northwestward movement of the Pacific Plate over a local volcanic “hot spot” has produced a series of islands, one after another in assembly line fashion. The result is a chain of volcanic islands (Hawaiian archipelago) that consists of eight major islands, from west to east, Ni’ihau, Kauai`i, O`ahu, Moloka`i, Lana`i, Kaho`olawe, Maui, and the Big Island of Hawai`i.

Geologists suspect that at one-time Haleakala was not only joined to the West Maui Mountains, like today, but also was a single landmass combined with the islands of Lana’i, Moloka’i, and Kaho’olawe — known as Maui Nui (literally, big Maui). The submergence of Maui Nui resulted as the volcanic body moved away from the Hawaiian hot spot. The lack of volcanic upbuilding combined with continued subsidence into the ocean floor eventually sank portions of the large island into the Pacific, providing us with the four separate islands we see today.

A similar fate awaits the Big Island in due time. As the hot spot “moves away” from the island (due to the Pacific Plate carrying the islands piggyback-style off to the north west) the Big Island too will fall victim to subsidence and erosion. Eventually the Big Island will likely find itself in a similar state to that of Maui Nui. It will become separate and smaller islands as the ocean encroaches on the flanks of each separate mountain.

Such is the geologic circle of life beyond the Hawaiian hot spot.

The mayor of Honolulu should plan a touristic visit to the tide gauge of Honolulu, after having studied at least a touristic guide, about the Hawaii Islands, and their geology, before signing directives taking as reliable the advice by “climate scientists”.

That is, clearly, everything but reliable.


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