Sunday, October 2, 2016

Questioning Tide Gauge ability to measure global mean sea level rise. (Thompson et al. 2016)

I came across this freshly released study that highlights the short coming of relying on Tide Gauges for estimating global mean sea level rise.  I'm posting this because it reminded me of my Virtual Debate with Dave Burton of NC-20 the North Carolina ocean science denial organization.  They are real estate focused folks who wanted the NC legislature to ignore climate science and sea level rise predictions when planning for the future.  A stellar example of willful ignorance in action.  Dave continues crusading for ignoring the facts at our disposal.

He has an obsessive focus on Tide Gauges and he claims that TGs prove that oceanographers don't know what they are talking about when they warn of accelerating sea level rise and it's consequences based on a combination of measurements.  Dave has particular contempt for satellite data, but never could explain why, in any meaningful manner.  {Dave, here's some more reasons that explain why you are wrong about your sea level claims.}


Tide Gauge Records May Underestimate 20th Century Sea Level Rise

Are long tide gauge records in the wrong place to measure global mean sea level rise? (Thompson et al. 2016) 

Abstract: Ocean dynamics, land motion, and changes in Earth’s gravitational and rotational fields cause local sea level change to deviate from the rate of global mean sea level rise. 

Here, we use observations and simulations of spatial structure in sea level change to estimate the likelihood that these processes cause sea level trends in the longest and highest-quality tide gauge records to be systematically biased relative to the true global mean rate. 

The analyzed records have an average 20th century rate of approximately 1.6 mm/yr, but based on the locations of these gauges, we show the simple average underestimates the 20th century global mean rate by 0.1  ±  0.2 mm/yr. Given the distribution of potential sampling biases, we find < 1% probability that observed trends from the longest and highest-quality TG records are consistent with global mean rates less than 1.4 mm/yr.

Highlights include enriched and related content of notable journal articles presented on Eos org AGU org AGU On Demand and in AGU journals

Leah Crane, September 26, 2016

Tide gauges can help measure sea level change, but their limited locations and short records make it hard to pinpoint trends. …

However, inferring average sea level change across the globe from these local measurements isn’t as straightforward as it may seem. Ocean dynamics, land motion, and changes in Earth’s gravity and rotation can all skew local sea level trends, and there are very few tide gauges that have collected data for more than 50 years. All these factors make it difficult to isolate the amount of average global rise that reflects global ocean warming and ice mass loss.

A new study by Thompson et al. evaluates how local and regional processes affect the amount of historical global sea level rise inferred from tide gauge records. They conclude that the best tide gauge records tend to underestimate the average rate of 20th century global sea level rise.

The scientists used a sample of the 15 longest, highest-quality tide gauge records—the records that are used most often by researchers when estimating global changes in sea level. 

The analysis also showed that this negative bias is not likely to be overcome by contributions from ice sheet melt and ocean dynamics.

As a result, the authors place a lower bound on 20th century sea level rise of about 1.4 millimeters per year during the 20th century, and the most likely "true" global rate was closer to 1.7 millimeters per year. ...

A list of the virtual debate between myself and Dave NC-20 Burton.

Shining light on NC-20 Burton's devious distortions.

Examples of the Attack on Science and Rational Constructive Learning.

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

NC-20 Burton responds, misses the point completely.

NC-20 says 'bring on the Carbon Dioxide'! - I say, What?

NC-20 Burton's five 'challenging' questions - a study in deception.

NC-20 Dave Burton runs to echo-chamber, Poptech's clubhouse.

Open note to Dave Burton (NC-20).

Dave Burton complains, yet remains a no-show.

HOTWHOPPER does Dave Burton's sea level claims.

The Seamonster does Dave Burton's sea level claims.

ncdave4life IPCC "Expert" Reviewer and battle of the Lists.

#1 considering malicious mischief in action: ncdave4life

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