Saturday, July 9, 2016

NC-20 Burton Why Do You Deliberately Misrepresent the Brest Tide Gauge Data?

Dave NC-20 Burton repeatedly claims he's never been shown to be wrong, he also loves claiming that sea level rise has not accelerated over the past century and that Tide Gauges are the gold standard.  One of his favorite Tide Gauges is at Brest, France which dates way back.  With graph in hand Dave claims “As you can see, there's been no apparent acceleration in sea-level rise there in the last hundred years.”

Interestingly when one looks at that graph through a slightly different filter, 
it's not so clear cut at all.  


Here's what happens when scientists do the numbers:

0.42 ± 0.18 mm/year Brest -1800s
1.14 ± 0.18 mm/year Brest -1900s
0.39 ± 0.17 mm/year Liverpool -1800s
1.22 ± 0.25 mm/year Liverpool - 1900s

Tide gauge datum continuity at Brest since 1711: France's longest sea-level record
Guy Wöppelmann, Nicolas Pouvreau, Alain Coulomb, Bernard Simon, Philip L. Woodworth

Now that I've given the punchline, let me back track and focus on one of the important differences between Dave Burton's approach and my own "process".  

I love to learn, I want to learn from my mistakes, I thirst for more and better information to help develop my overall understanding of this Earth I love and that we depend on for everything.  On the other hand, NC-20 Burton is into repeating agenda focused PR soundbites and refusing to listen to anything anyone else is trying to explain.  Never allowing new information to percolate and be incorporated into his overall world view.  
We'll start with Burton's spiel:

By far the greatest part of the anthropogenic contribution to GHG levels has occurred since the 1940s. What matters for validating or falsifying the hypothetical causal relationship between GHG levels and sea-level rise is what happened to the rate of sea-level rise in response to the addition of all that CO2 & CH4.

The answer is, nothing at all. Increasing CO2 from under 310 ppmv to ~400 ppmv, and increasing CH4 from 1.2 ppmv to 1.8 ppmv, has caused no increase at all in the rate of sea-level rise.

Here's a graph of >200 years of sea-level measurements (with a couple of gaps) from Brest, France:
As you can see, there's been no apparent acceleration in sea-level rise there in the last hundred years.

DavidAppell wrote, "Prove it. With mathematics, not eyeballing."
In the first place, if you can't eyeball a graph and tell whether or not there's significant acceleration, you have no business working in science.

But, since you asked, here's an Excel spreadsheet with monthly sea-level measurements at Brest, France, since January, 1900, downloaded from NOAA:
I inserted an Excel chart, with a linear trendline in red, and then a quadratic trendline in green. Here it is:
Keep in mind, for this time frame, we are talking about small sea level rise.  No one denies that a sea level rise of 6 inches a year would be modest indeed and manageable.  Thing is, only the deliberately isolated can harbor the notion that this Earth is not experiencing the beginnings of a period of greatly increased sea level rise due to the observed accelerating deterioration and melting of our cryosphere of which there is no doubt.  NC-20 Burton demands that we only stare at the view in our rear view mirrors. 

Wake up!  We are speeding forward!

DavidAppell, you could have done this simple analysis yourself, and seen for yourself the lack of sea-level rise acceleration in the tide-gauge records (since at least the 1920s in all long-term records, and even longer in most, including Brest).

Since I have "Proved it With mathematics," as you demanded, will you now cease repeating your mistaken claim that sea-level rise is accelerating?

Brest, France is not a proxy for global sea levels.
As a certain map makes abundantly clear.


Dave Burton
to citizenschallengeAE 20 hours ago 

Pete wrote, "Brest, France is not a proxy for global sea levels.”

It's not a proxy at all. It's actual, measured sea-level, the longest such measurement record in the world. It goes way back to 1807.

I mentioned that the NOAA graph of sea-level at Brest, France looks very linear for more than a century. But what seemed obvious to me apparently wasn't obvious to DavidAppell, because he asked I "prove it with mathematics." So, I did.

He hasn't even replied. A "thank you" would have been nice.

Then again perhaps Brest, France can be a rough proxy for global sea level rise.  All depends on how much information one is willing to expose oneself to.

When looking at your graph the first thing that came to mind is, does that line even attempt to show decadal trends?  Doesn’t seem like it.  It looks more like an average for the entire period.  So I decided to look for something specific about Brest that would offer more than NC-20's cartoonish assessment.

Seek and ye shall find:

Tide gauge datum continuity at Brest since 1711: France's longest sea-level record

Guy Wöppelmann, Nicolas Pouvreau, Alain Coulomb, Bernard Simon, Philip L. Woodworth

First published: 26 November 2008
DOI: 10.1029/2008GL035783

[1] The issue of a possible tide gauge datum discontinuity at Brest, caused by the bombing of the city in August 1944, is discussed. This issue is very important, as many scientists have used this long record to derive a long-term sea level trend estimate for use within global sea level rise studies. A detailed analysis of historical leveling information, and comparison of sea level data between adjacent stations, proved to be worthwhile, even beyond this initial scope of the study: it led to an accurate datum connection between recently rediscovered 18th century sea level data (back to 1711) and those of the present day. 

The study provides additional evidence that the onset of recent rapid sea level rise most likely took place in the late 19th century, in agreement with the nearby Liverpool sea-level record and with independent results from sediment cores collected in salt marshes located in both hemispheres.

1. Introduction
[2] The Brest sea level record, dating back to 1807, is the longest mean sea level record in the data archive of the Permanent Service for Mean Sea Level (PSMSL) [Woodworth and Player, 2003] and the Brest station nowadays contributes to the Global Sea Level Observing System [Intergovernmental Oceanographic Commission (IOC), 1997]. Brest data have been included in many sea level studies including those concerned with recent sea level rise [e.g., Cartwright, 1972; Gornitz et al., 1982; Barnett, 1984; Pirazzoli, 1986; Woodworth, 1987, 1990, 1999; Trupin and Wahr, 1990; Douglas, 1991, 2001; Araujo et al., 2002; Holgate and Woodworth, 2004; Nakada and Inoue, 2005; Church and White, 2006; Bindoff et al., 2007; Leorri et al., 2008]. Its time series is substantially complete but small gaps can be filled by interpolation, leading to a data set which is 92% complete between 1807 and the present day [Pouvreau et al., 2006; Wöppelmann et al., 2006]. …

2. Data Sets
[3] Two types of data have been used to assess the continuity of the Brest tide gauge datum: (1) data obtained from historical leveling surveys involving the primary tide gauge benchmark, usually designated as the ‘TGBM’, and (2) tide gauge records from neighboring stations. The TGBM is a key element of a tide gauge station since it defines the datum to which the values of sea level are referred [e.g., IOC, 1985; Wöppelmann and Pirazzoli, 2005]. …

3. Datum Continuity From Leveling Surveys
[6] Six first-order leveling surveys were found in the IGN archives …
Table 1. Leveling Results at Different Epochs for the Brest Primary Tide Gauge Benchmark NO-1 (1889 Marker Name) With Respect to Neighboring Benchmarks of the 1st Order Leveling Network …

5. Discussion and Conclusions
[10] Estimation of relative trends in sea-level from tide gauge time series can be significantly biased if offsets are present. The documented historical first-order leveling surveys performed in the vicinity of the Brest tide gauge indicate that its datum remained “stable” and consistent at a few millimeters level over the period 1889-1996, in spite of the bombing of the city during the Second World War, and subsequent interruption in the Brest time series. 

No evidence of an offset affecting the datum continuity at Brest sea-level record can be detected by comparison to adjacent stations other than Newlyn. It is certainly tempting to apply an offset of about 20 mm to the Brest pre- and post 1944 records in order to bring its rate over the past century in agreement with the rate of sea-level rise obtained at Newlyn [Douglas, 2008], but this is definitely not supported by the analysis of historical leveling data, nor by extending the comparison to other sites. Hence, the issue of the difference of the relative sea level rise rates observed at Brest and Newlyn remains open. …

…Nevertheless, there are some similarities in their rates of relative sea level rise. Linear regressions of segments of the MHW records are similar:  a trend of 1.22 ± 0.25 mm/year is obtained for the 20th century at Liverpool [Woodworth, 1999], whereas a trend of 1.14 ± 0.18 mm/year is obtained at Brest for the same period [Pouvreau, 2008]. The trends are further consistent over the 19th century period (0.39 ± 0.17 mm/year and 0.42 ± 0.18 mm/year respectively), indicating a recent significant increase in the rate of sea level rise at both sites. 

Moreover, the question when this apparent rise commenced is an important issue for long term sea level change, as a key observational constraint on climate models [Woodworth, 2006]. Both instrumental records show a roughly coincident increase in the rate of relative sea-level rise around the end of the 19th century. 

Our conclusion as to the timing of this onset of rapid sea level rise is consistent with independent results stemming from sediment cores collected in salt marshes, either in the northern hemisphere: near New York, USA [Donnelly et al., 2004], Nova Scotia, Canada [Gehrels et al., 2005], near Bilbao, Spain [Leorri et al., 2008], or in the southern hemisphere: near Pounawea, New Zealand [Gehrels et al., 2008]. 

The similar timing for the onset of the recent sea level rise, which has been found at both hemispheres from different types of data, supports the global significance and intensity of the acceleration of the sea-level rise compared to pre-industrial rates. … LINK

Tide Gauge
0.39 ± 0.17 mm/year Liverpool -1800s
0.42 ± 0.18 mm/year Brest -1800s
1.22 ± 0.25 mm/year Liverpool - 1900s
1.14 ± 0.18 mm/year Brest -1900s

FYI - 3.0 ± 0.7 mm/year between 1993 and 2010
Probabilistic reanalysis of twentieth-century sea-level rise
  • Carling C. Hay,
  • Eric Morrow,
  • Robert E. Kopp
  • Jerry X. Mitrovica
    "Our analysis, which combines tide gauge records with physics-based and model-derived geometries of the various contributing signals, also indicates that GMSL rose at a rate of 3.0 ± 0.7 millimetres per year between 1993 and 2010, consistent with prior estimates from tide gauge records4. The increase in rate relative to the 1901–90 trend is accordingly larger than previously thought; this revision may affect some projections11 of future sea-level rise."

    Tide Gauge and Satellite (current rate)
    the consensus on
    Global Mean Sea Level (GMSL) rise


    NC-20 Burton please explain again how you figure there's been no acceleration in sea level rise?

    What do you know that all those authorities can't figure out?

    Or should I ask, why do you think you're smarter than this world wide community of experts.


    2015 State of U.S. “Nuisance” Tidal Flooding
    William V. Sweet and John J. Marra | June 8, 2016

    National Oceanic and Atmospheric Administration’s Center for Operational Oceanographic Products and Services and National Centers for Environmental Information

    High tide flooding, measured locally by National Oceanic and Atmospheric Administration (NOAA) tide gauges, is described as “nuisance”, “sunny-day” and “recurrent”. Such minor flooding is increasingly common with little or no storm effects (Sweet et al., 2014). Impacts include degraded storm water systems, infiltration into waste-water systems, contamination of fresh water supplies and salt-water flooding of roads, homes and businesses; tidal flooding is disrupting commerce and ways of life. 

    During 2015, there was extensive reporting of tidal flooding impacting cites in New Jersey, Delaware, Maryland, Virginia, North and South Carolina, Georgia, Florida, Louisiana, Texas and California to name a few.

    Tidal flooding is increasing in frequency within U.S. coastal communities due to sea level rise (SLR) from climate change and local land subsidence. Tidal flooding is further exacerbated by climate variability of the El Niño Southern Oscillation (ENSO). Decades ago powerful storms caused such impacts, but due to SLR, more common events are now more impactful. Event frequencies are increasing rapidly – two to three times or more frequent than just 20 years ago (Table 1). 

    Annual tidal flood rates have entered a sustained acceleration phase at many locations (Sweet and Park, 2014) as the annual distribution of daily highest tides steadily surpasses “fixed” elevations. Thus, once flooding becomes problematic, impacts will become chronic rather quickly and communities should plan for this eventuality.

    2015 Summary
    This document updates the number of days during the May 2015 – April 2016 (2015) meteorological year with a nuisance tidal flood. Nuisance flooding is defined as a water level measured by NOAA tide gauges ( above the local NOAA National Weather Service (NWS) threshold for minor impacts ( established for emergency preparedness (Figure 1a). 

    We highlight the 27 long-term gauges across the U.S. examined by Sweet and Park (2014) and an additional gauge in Virginia Key (Miami region) because of the extent of tidal flooding that occurred there in 2015.

    2015 Conditions. During 2015, anomalously high (>0.1 m) coastal sea levels persisted (Figure 1b) along the U.S. Southeast and Gulf Coast and parts of the West Coast. This increased the reach of typical storm surges and high tides. In response, the frequency of nuisance tidal flooding in 2015 increased by more than 50% on average across all locations as compared to 2014 (Figure 1c). 

    During 2015, several locations experienced all-time records (see Table 1), including Wilmington (90 days), Charleston (38 days), Port Isabel (36 days), Mayport (19 days), Virginia Key (Miami region) (18 days), Key West (14 days) and Fernandina Beach (7 days). Frequencies were at or above the 1950-2013 trend expected values for 2015 at most locations. It is important to note that the overall number of daily exceedances per year is correlated to the height of the local NWS threshold. Where the thresholds are low, more flooding occurs (e.g., Wilmington); where thresholds are highest such as in St. Petersburg and Galveston (reflecting hurricane flood mitigation structures), little to no exceedances were recorded. 

    ~ ~ ~ ~ ~ ~ ~

    NOAA Technical Report NOS CO-OPS 073
    Sea Level Rise and Nuisance Flood Frequency Changes around the United States

    The National Oceanic and Atmospheric Administration (NOAA) water level (tide) gauges have been measuring water levels around the U.S. for over a century, providing clear evidence of sea level rise relative to land (SLR) around most of the continental United States and Hawaii. As SLR increases mean sea level (MSL), there is naturally an increase in tidal datum elevations, which are typically used to delineate inundation thresholds. Direct consequences of rising sea level against fixed elevations such as today’s built infrastructure also include increased inundation during extreme events both spatially and temporally. Not only are extreme flooding events reaching higher grounds and covering larger areas due to SLRrel, the frequency and duration of these extreme flood events are increasing.

    Another consequence of SLRrel is the increase in lesser extremes such as occasional minor coastal flooding experienced during high tide. These events are becoming more noticeable and widespread along many U.S. coastal regions and are today becoming more of a nuisance. As sea levels continue to rise and with an anticipated acceleration in the rate of rise from ocean warming and land-ice melt, concern exists as to when more substantive impacts from tidal flooding of greater frequency and duration will regularly occur. Information quantifying these occurrences to inform mitigation and adaptation efforts and decision makers is not widely available. 

    ~ ~ ~ ~ ~ ~ ~

    No comments: