Sea Level Speculations in Honolulu and Macau
ABSTRACT: It has been claimed in the press, based on speculations from a not even peer-reviewed report in one case, and one tabloid-like science peer-reviewed paper in the other, that the sea levels may rise of 50 cm by 2060 in Macau, and 0.91 metre by 2050 in Honolulu.
In Macau, where subsidence is small, the sea levels have been rising 1925/1 to 1985/5 at a negligible rate of 0.26 mm/yr. with a negative acceleration of -0.0880 mm/yr². In Honolulu, where subsidence is larger, the sea levels have been rising 1905/1 to 2018/5 at a rate of 1.45 mm/yr. with a negative acceleration of -0.00535 mm/yr².
All the long-term trend tide gauges of the world consistently show relatively small rates of rise, mostly dictated by the local subsidence, and negligible accelerations, both positive and negative.
Hence, it may take 2,000 years rather than 42 to see the 50 cm sea level rise in Macau, and 571 years rather than 32 to see the 0.91 metre sea level rise in Honolulu.
Ocean and coastal management should be based on real sea level measurements and not suppositions.
Keywords: sea level measurements, sea level rate of rise, sea level acceleration
SEA LEVEL SPECULATIONS IN HONOLULU
As reported in www.smartcitiesdive.com/news/honolulu-mayor-orders-preparations-for-sea-level-rise/528322/,
Honolulu Mayor Kirk Caldwell signed a directive static1.squarespace.com/static/59af5d3cd7bdce7aa5c3e11f/t/5b4d607688251ba9e4b51233/1531797818272/
PRESS+RELEASE+-+Mayor{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117}27s+Directive+18-01+{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117}287-16-18{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117}29.pdf
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 www.hawaii.edu/news/2018/07/16/climate-change-guidance/ 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 sealevel.info), the mean sea level trend is +1.48 mm/year with a 95{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117} 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.
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More than three feet, the sea level rise in Honolulu will be likely 0.1856 feet by mid-century. Also, it may take 517 years, rather than 32 years, to make a 3 feet sea level rise.
The GNSS time series of the dome of FOMO nearby the tide gauge, as analysed by Nevada Geodetic Lab (NGL), geodesy.unr.edu, suggests a subsidence rate of -0.256±0.944 mm/yr. (data 2006.4148 to 2018.4367).
This is 100{154653b9ea5f83bbbf00f55de12e21cba2da5b4b158a426ee0e27ae0c1b44117} of the observed relative sea level rise at the tide gauge instrument. 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 micrometres 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 longterm 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, https://www.data.jma.go.jp/gmd/kaiyou/english/sl_trend/sea_level_around_japan.html 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 tide gauges affected by Page 323 New Concepts In Global Tectonics Journal, Vol. 6, No 3, September, 2018 www.ievpc.org crustal movement are excluded.
Things are also going bad for alarmism also moving to the West coast of North America.
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