The sea levels of the Solomon Islands are rising of 7-10 mm yr-1 only by cherry picking

Guest essay by Albert Parker

Albert, Leon, Grinham, Church, Gibbes & Woodroffe recently published in Environmental Research Letters [1] a paper claiming the “rates of sea-level rise in the Solomon Islands over the past two decades are amongst the highest globally, averaging 3 mm yr−1 since 1950 and 7–10 mm yr−1 since 1994” echoing wrong claims by others. This “evidence” of 7-10 mm yr-1 sea level rise due to man-made global warming is what is then trumpeted in catastrophic press releases such as [2, 3]. Titles obviously catastrophic “rising sea levels blamed for wiping out five islands”. The leading author declares “the Solomons was considered a sea-level hotspot because rises there are almost three times higher than the global average”. However, as always with the claims of “Intergovernmental experts”, the right numbers are at the most one fourth of the claim

The alarmistic claim originates from riding the positive phase of the inter-annual, decadal and multi-decadal oscillations typical of the sea levels over a cherry picked short time window of 10-15 years, neglecting what was measured before 1994 by another tide gauge in pretty much same location, and also neglecting what has been measured in the same tide gauge since 2009.

Short records do not permit to clear the trend of the inter-annual, decadal and multi-decadal oscillations [4-8]. In the Solomon Islands there is no tide gauge long enough to infer a proper trend. However, the information available permits to dismiss the alarmist claim of 7-10 mm yr-1 rate of rise.

The high quality Revised Local Reference (RLR) data set of the PSMSL [9, 10] includes the two tide gauges of Honiara II and Honiara B.

Both tide gauge records are short, about 20 years long.

Honiara B is part of the “substitutional evidence” of the Pacific Sea Level Monitoring (PSLM) project [11].

Honiara II ceased operation 5 months after Honiara B started operation, and it is forgotten since then.

The data of Honiara B are updated every year in PSMSL [10], and every month in PSLM [12] where in addition to the monthly average mean sea level (MSL), also the monthly minimum and maximum are provided.

No leveling has been performed for Honiara B vs. Honiara II to permit the construction of a composite record that could have lowered and made more reliable the sea level rise estimation. However, both tide gauges were recording during the year 1994 for 5 months, August to December. The differences in between the RLR data for Honiara B and Honiara II are 355, 357, 355, 356 and 359 mm. Therefore, we may shift one time series vs. the other of 356 mm to obtain the composite record of Fig 1.

Starting from July 1994, the start of the Honiara B record, the rate of rise of sea levels increased up to April 2009 when it reached a maximum of 9.25 mm yr-1. The 15 years’ time window is insufficient.

After April 2009, the rate of rise since July 1994 started to decrease and it is now +5.50 mm yr-1. The time window of 21 years is still insufficient. Only focusing on Honiara B the only possible statement is the apparent rate of rise is +5.50 mm yr-1 (and not 7-10 mm yr-1) but this number is not significant.

Also including Honiara II, starting from December 1974 the rate of rise is +2.81 mm yr-1. The time window is now 42 years long, still insufficient, but certainly more reasonable. Considering 60-70 years of data are needed to start understanding a trend in sea levels, very likely these +2.81 mm yr-1 are still an overestimation of the relative rate of rise.

The editorial board and the reviewers should certainly pay more attention to extravagant claims of sea level rises of 10 mm yr-1 that are based on short cherry-picked periods.

References

1. S. Albert, J. X. Leon, A. R. Grinham, J. A. Church, B. R. Gibbes and C. D. Woodroffe (2016), Interactions between sea-level rise and wave exposure on reef island dynamics in the Solomon Islands, Environmental Research Letters 11:054011.

2. http://www.abc.net.au/news/2016-05-07/rising-sea-levels-blamed-for-wiping-out-five-islands/7392986

3. http://phys.org/news/2016-05-sea-level-islands-solomons.html

4. A. Parker (2013), Oscillations of sea-level rise along the Atlantic coast of North America north of Cape Hatteras, Natural Hazards 65(1):991-997.

5. A. Parker (2013), SEA-LEVEL TRENDS AT LOCATIONS OF THE UNITED STATES WITH MORE THAN 100 YEARS OF RECORDING, Natural Hazards 65(1):1011-1021.

6. A. Parker, M. Saad Saleem & M. Lawson (2013), Sea-Level Trend Analysis for Coastal Management, Ocean & Coastal Management 73: 63–81.

7. A. Parker (2013), MINIMUM 60 YEARS OF RECORDING ARE NEEDED TO COMPUTE THE SEA LEVEL RATE OF RISE IN THE WESTERN SOUTH PACIFIC, Nonlinear Engineering. 3(1):1-10.

8. A. Parker & C.D. Ollier (2016), COASTAL PLANNING SHOULD BE BASED ON PROVEN SEA-LEVEL DATA, Ocean and Coastal Management. Doi: 10.1016/j.ocecoaman.2016.02.005.

9. http://www.psmsl.org/data/obtaining/stations/1373.php

10. http://www.psmsl.org/data/obtaining/stations/1861.php

11. http://www.bom.gov.au/pacific/projects/pslm/

12. http://www.bom.gov.au/ntc/IDO70061/IDO70061SLD.shtml

Added by Anthony:

This graph from the 2007 IPCC AR4 report is quite interesting, it shows that in the Solomon Islands region, in blue on the map, sea level was declining and was clearly linked to the Southern Oscillation Index.

They write:

An EOF analysis of gridded thermosteric sea level time series since 1955 (updated from Lombard et al., 2005) displays a spatial pattern that is similar to the spatial distribution of thermosteric sea level trends over the same time span (compare Figure 5.20 withFigure 5.16b). In addition, the first principal component is negatively correlated with the Southern Oscillation Index. Thus, it appears that ENSO-related ocean variability accounts for the largest fraction of variance in spatial patterns of thermosteric sea level. Similarly, decadal thermosteric sea level in the North Pacific and North Atlantic appears strongly influenced by the PDO and NAO respectively.

Source: https://www.ipcc.ch/publications_and_data/ar4/wg1/en/ch5s5-5-4-1.html

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