The latest conspiracy theory from WUWT: sea level numbers are imaginary

Deniers must be at their wits end. Although if the article (archived here) that Anthony Watts posted at WUWT yesterday is any indication, the wit of deniers is quite small in stature, so they don't have to travel far to get to the end.

A regular denier at WUWT is Kip Hansen. Kip's latest hypothesis is that sea level numbers are imaginary. This is what he thinks is "imaginary":

Source: Sea Level Research Group U Colorado

Kip has woven a conspiracy that goes something like this.

Kip starts with the logical fallacy of personal incredulity. He doesn't believe it therefore it isn't so. Logical fallacies are Telltale Technique No. 2 of climate science denial. Kip expressed his logical fallacy as a question:

Is it really possible to measure something like sea level (or surface air temperature 2 meters above the ground or sea surface temperature) with “a high degree of accuracy”?

The science of sea level changes

The answer is that it is possible to measure changes in sea level. The way that sea level change is measured is described on the website of the CU Sea Level Research Group, University of Colorado. In the above chart, the researchers indicate that the error range is +/- 0.4 mm/year. That website also indicates other estimates from different sources:

• CU: 3.3 ± 0.4 mm/yr
• AVISO: 3.3 ± 0.6 mm/yr
• CSIRO: 3.2 ± 0.4 mm/yr
• NASA GSFC: 3.2 ± 0.4 mm/yr
• NOAA: 3.2 ± 0.4 mm/yr (w/ GIA)

The FAQ indicates what "global mean sea level" means when used in the context of satellite altimetry:

The term "global mean sea level" in the context of our research is defined as the area-weighted mean of all of the sea surface height anomalies measured by the altimeter in a single, 10-day satellite track repeat cycle.  It can also be thought of as the "eustatic sea level." The eustatic sea level is not a physical sea level (since the sea levels relative to local land surfaces vary depending on land motion and other factors), but it represents the level if all of the water in the oceans were contained in a single basin. Changes to this eustatic level are caused by changes in total ocean water mass (e.g., ice sheet runoff), changes in the size of the ocean basin (e.g., GIA), or density changes of the water (e.g., thermal expansion). The time series of the GMSL estimates over the TOPEX and Jason missions beginning in 1992 to the present indicates a mostly linear trend after correction for inter-mission biases between instruments. The GMSL rate corrected for GIA represents changes in water mass and density in the oceans. These changes are thought to be predominantly driven by thermal expansion of the oceans and land ice melt (Greenland and Antarctic ice sheets and glaciers).

When it comes to estimating error, this is covered in a paper by Nerem et al (2010). Here is what the scientists wrote about how altimeter measures are calibrated with tide gauges (my emphasis and paras):

The tide gauge calibration is, however, extremely valuable for quantifying time-dependent errors (i.e., drift errors) in the altimetric time-series. 

For the purposes of this paper, we need to briefly review several aspects of the tide gauge calibration method....

...First, the dominant rate error in the tide gauge calibration is the uncertainty arising from imperfect knowledge of the land motion rates at the tide gauges. Because the tide gauges measure sea level relative to the adjacent land and are not typically known in an absolute reference frame, one must make land motion corrections in order to make absolute ocean height measurements. When the altimetric and tide gauge heights are differenced, land motions and altimeter drift cannot be separated, meaning that the land motion uncertainty places a limit on our ability to determine altimeter drift rates. At present, this error is estimated to be 0.4 mm/yr (Mitchum 2000), and this error must be added to the error obtained from fitting trends to the altimeter height series, which are typically much smaller. In determining the rate error estimate on sea level changes, the land motion errors and the fitting errors are assumed to be independent.

Second, the tide gauge method not only provides a drift time-series but also gives a time-series of the errors in these estimates by propagating the errors at each tide gauge through to the final globally averaged drift estimate series. These errors can then be compared to the scatter in the altimetric time-series of global sea level as a check on both measurement systems and the tide gauge method itself.

Third, the altimeter, tide gauge difference series are corrected for tide model errors by removing variance at the tidal alias frequencies. Differences at the tidal frequencies are expected to arise from errors in the model used to correct the altimetric heights and also from local deformations of the tidal signals near topography, which is where the tide gauges are. The specific tidal components that are fit and removed from the difference series depends on the length of the time-series. This means that shorter records are expected to have somewhat higher noise than longer ones, which is especially relevant for Jason-2. 

Kip's conspiracy theory

In case you think that Kip is just questioning the accuracy of the numbers, and not weaving a conspiracy - you'd be wrong. Kip indulged in "something must be wrong" and "nefarious intent" - hallmarks of conspiracy ideation. He wrote the following - with my comment on his conspiracy ideation at the end of each of the three dot points:

Today’s discussion is one way of looking at the current trend in Science in which attempts are made to reduce very complicated dynamic systems to a single number which can then be graphed against time, usually in attempts to do one or more of the following:

1. to cast blame for the increasing or decreasing number on a substance or action or group, usually incorrectly [Kip is alleging "nefarious intent" or "questionable motives"]
2. using two such graphs of single numbers to correlate some single number with some other single number to sell a desired story, usually to cast blame or give credit, usually incorrectly [Kip is again alleging "nefarious intent"]
3. to bring attention to [read this as: to cause public concern or worry about] some rising or falling single number in hopes of generating gain [in research funds, fame, public sympathy, public or political support], usually unwarranted [Kip is claiming that "something must be wrong" and "nefarious intent" and "questionable motives" on the part of researchers]

Different estimates, same results

It's not just satellite altimetry - researchers have also extended the sea level changes over time, going back a long way. I've already written about this a number of times, for example - in a previous article I summarised recent papers on sea level changes:

...tide records produce a similar result to the satellites. Here are some reports of sea level trends from different teams, as I collated in an article last year, from tide gauges and satellites:

• Church and White (2011) - tide gauges and satellite altimetry: For 1993–2009 and after correcting for glacial isostatic adjustment, the estimated rate of rise is 3.2 ± 0.4 mm year−1 from the satellite data and 2.8 ± 0.8 mm year−1 from the in situ data.
• Jevrejeva et al (2013) - tide gauges compared with satellite: There is a good agreement between the rate of sea level rise (3.2 ± 0.4 mm·yr−1) calculated from satellite altimetry and the rate of 3.1 ± 0.6 mm·yr−1 from tide gauge based reconstruction for the overlapping time period (1993–2009).
• Cazenave et al (2014) - satellite altimetry: We find that when correcting for interannual variability, the past decade’s slowdown of the global mean sea level disappears, leading to a similar rate of sea-level rise (of 3.3 ± 0.4 mm yr−1) during the first and second decade of the altimetry era.
• U Colorado - satellite altimetry: 3.2 +/- 0.4 mm / year since 1993

Notice that U Colorado now reports the current trend as 3.3 +/- 0.4 mm / year since 1993, which is higher than that reported up to 2014.

The point is that it's not just one group that is reporting similar findings, using different measures. The numbers are not imaginary. They are as real as you'll get. The only imaginary numbers are those that deniers cannot come up with to disprove science.

From the WUWT comments

There was some discussion about the Olympic Games, and a lot of comments from people who, like Kip, succumb to the logical fallacy of personal incredulity. They usually love satellites as being the ants pants, absolutely correct - except when they produce results they don't like. There were also some comments from people who didn't fall for Kip's conspiracy theorising imagination hook, line and sinker.

jccarlton makes the startling observation (not) that the sea surface isn't perfectly flat, so he reckons you can't get accuracy at the seaside. He rejects tide gauge measurements. Well, guess what - not all measures are taken at the seaside. The satellite measures are over the ocean proper.

October 9, 2015 at 10:30 pm
Reblogged this on The Arts Mechanical and commented:
Like Willis and Mr. Hansen I’ve spent a good part of my life near tidewater. Mr. Hansen is absolutely right that there is no possible way you could measure sea level to the accuracy that the climate team claims. The error potential in the instruments used in larger than the potential measured value, to say nothing of the fact, that as fluid, seawater is very difficult to measure. For that matter it’s impossible to get measurements to within +/- 2mm in a tank measuring flow. So how are we to expect such accuracy from a measurement taken from a seaside.

peyelut wants to polish turds for some reason, and figures they are unpolishable. He doesn't have anything to contribute about sea level though.

October 9, 2015 at 10:31 pm
The bottom line is: “You can’t polish a Turd”.

Bob is the first to show a smidgen of insight, discussing the trend rather than any absolute "level"

October 9, 2015 at 10:42 pm
Interesting article, Kip. Averages of averages may or may not have value, in my opinion.
For example: If you took the average monthly/daily global sea level readings calculated for the last fifty years, maybe the resulting number means little, but it seems to me that it is the trend that reveals information when viewed over the length of the series. Where am I going wrong?

fossilsage has a thought about jumping molecules, which he couldn't keep to himself:

October 9, 2015 at 11:06 pm
Correct me if I have misunderstood but I have often wondered about the issue in the finite probability that if all the molecules in my desk oscillated ( “jumped”) in the same direction then my desk, of course, would jump. Unless of course the use of probability in ordering the conduct of the universe is just such an “imaginary number” and the real universe would NEVER let the desk make its finitely possible leap even over an infinite period of time. 

Leonard Lane's thought is about a rowboat. He seems to think he's come up with an insurmountable objection that scientists have never thought of, let alone overcome.

October 9, 2015 at 11:45 pm
Very good article. Thank you.
Anyone who has ever stood up in a rowboat on a river, lake, or sea knows that any point on the boat. (prow, stern, highest point, etc.) does not follow a simple up and down regular motion. Each point seems to roll generally up and down in some kind of complex path and each cycle appears to be different. That’s for a single point. Now imagine being able to see all points on the boat at the same time. Furthermore, as you stand and move your body to maintain a standing position, you influence the movement of the boat. Magnify the complexities you see in a small boat, to the great distances as the oceans surround the earth.
So what is the average elevation of any point on the boat? How long would you have to measure the elevation of that point to have the average elevation of that point have meaning? Would the wind, tides, movement of things and people on the boat make each measurement at a point unique? Now ask the same question for every point on the boat, and every point on the world’s oceans surface (whatever that means).
If your imagination is good and you are a land lubber, maybe you should reach for the seasickness medicines.
It doesn’t take much imagination to ask the above questions. But who can answer them?

TonyL is a bit worried that denier articles (like Christopher Monckton's) will have no meaning if Kip's article is taken as gospel. Where would that leave the all-hallowed, consecrated, perfect UAH and RSS lower troposphere temperature data? Of course it doesn't mean that all measures are imaginary. Just the ones deniers don't like. Deniers are nothing if not wholly inconsistent. They are quite able to hold two contradictory notions in their head at the same time.

October 9, 2015 at 11:51 pm
It is certainly true that many have overstated the meaning of their measurements. rgb’s description of the CIMP ensemble averages is most apropos.
I would like to make the point that we take care not to overstate the problem. At base, we can still measure things, and those measurements are real and can be useful. Also, we do not want to get carried away and reject measurements of derived quantities as imaginary, just because they are derived quantities. The CIMP ensemble averages are surely imaginary, in the context of this essay. The mass of a platinum cylinder most surely is not, even though mass is a derived quantity. (We say we measure mass as a more fundamental quantity than weight, but in reality, we usually determine the weight in a gravitational field.)
{Please, no semantic warfare on the point}.

AndyE pointed out that some people are able to detect rising seas, and fortunately for them, took action:

October 10, 2015 at 12:12 am
Very interesting – but does it really matter whether the numbers are imaginary or not? As long as they are useful. The Dutch noticed some numbers a few hundred years ago, didn’t fuss about the quality of their imagination; but realised that the figures were going one way – so simply built higher dams. And, in hindsight, we agree that was a wise decision. 

Frederick Colbourne wrote a very long comment in which he disagreed with Kip's "imaginary" claim, though Frederick made it clear he rejects climate science.

October 10, 2015 at 2:26 am (excerpt)
Interesting discussion, but defining “imaginary numbers” this way in a scientific discussion adds nothing whatsoever to understanding.

I am skeptical about global climate alarmism but that does not make me accept the idea that real physical phenomena are imaginary. Rather I am skeptical because I believe the level of uncertainty in the science is still to high for me to accept that human activities are sufficient to overcome the internal and external climate variability that results from natural processes.

Leo Smith doesn't go for Kip's "imaginary" numbers either, and said so at length:

October 10, 2015 at 2:43 am (some excerpts)
I have to say this is a muddled essay, and I didn’t really like it. For reasons I am struggling to express.,

Firstly it is vaguely anti-science and anti-mathematics. Like much of the AGW outpourings it pretends to belittle a science it doesn’t really understand with appeals to ‘common sense’ (instead of ‘97% of scientists’ etc).

Secondly, the author appears to suffer from an extreme case of Rational Materialism. He thinks there are ‘facts’ and there are ‘models’ and never the twain shall meet. ...

...In short if you are going to regard the world as a rational materialist does, that that touch feely stuff is in fact Reality and has an independent existence that is quite unconcerned about whether people believe in it or not,…then measuring it cannot be an ideological mistake, and just because its hard to measure, doesn’t mean it doesn’t have size.. We cannot say ‘sea level has no meaning’ when we can go to the beach and watch the tides come in and go out and realise that that is in fact what sea level is, and does. And if year upon year it seems to come in a bit further every year, then we can surely say the sea level is rising… and if other people elsewhere in the world report similar, then we can give meaning to the phrase ‘global sea levels are rising’. And indeed try and put some ‘value’ on that rise, and rate of rise. ...

References and further reading

Nerem, R. S., D. P. Chambers, C. Choe, and G. T. Mitchum. "Estimating mean sea level change from the TOPEX and Jason altimeter missions." Marine Geodesy 33, no. S1 (2010): 435-446. DOI:10.1080/01490419.2010.491031 (pdf here)

From the HotWhopper archives

• Topsy turvy - Wondering Willis Eschenbach tells big whoppers about sea level. - August 2014
• Sea levels and global ice volumes over the past 35,000 years - October 2014
• Satellites rule in deniersville, except when sea levels are rising - August 2015