Above: Mt Erebus, Antarctica
picture by Sean Brocklesby
A press release today by the University of Washington makes a claim that Antarctica is warming and has been for the last 50 years:
“The study found that warming in West Antarctica exceeded one-tenth of a degree Celsius per decade for the last 50 years and more than offset the cooling in East Antarctica.”
…
“The researchers devised a statistical technique that uses data from satellites and from Antarctic weather stations to make a new estimate of temperature trends.”
…
“People were calculating with their heads instead of actually doing the math,” Steig said. “What we did is interpolate carefully instead of just using the back of an envelope. While other interpolations had been done previously, no one had really taken advantage of the satellite data, which provide crucial information about spatial patterns of temperature change.”
Satellites calculate the surface temperature by measuring the intensity of infrared light radiated by the snowpack, and they have the advantage of covering the entire continent. However, they have only been in operation for 25 years. On the other hand, a number of Antarctic weather stations have been in place since 1957, the International Geophysical Year, but virtually all of them are within a short distance of the coast and so provide no direct information about conditions in the continent’s interior.
The scientists found temperature measurements from weather stations corresponded closely with satellite data for overlapping time periods. That allowed them to use the satellite data as a guide to deduce temperatures in areas of the continent without weather stations.
…
Co-authors of the paper are David Schneider of the National Center for Atmospheric Research in Boulder, Colo., a former student of Steig’s; Scott Rutherford of Roger Williams University in Bristol, R.I.; Michael Mann of Pennsylvania State University; Josefino Comiso of NASA’s Goddard Space Flight Center in Greenbelt, Md.; and Drew Shindell of NASA’s Goddard Institute for Space Studies in New York City. The work was supported by grants from the National Science Foundation.
Anytime Michael Mann gets involved in a paper and something is “deduced” it makes me wary of the veracity of the methodology. Why? Mann can’t even correct simple faults like latitude-longitude errors in data used in previous papers he’s written.
But that’s not the focus of the moment. In that press release they cite NASA satellite imagery. Let’s take a look at how the imagery has changed in 5 years.
NASA’s viewpoint – 2004
Click for larger image
NASA’s Viewpoint 2007 (added 1/22)
NASA’s viewpoint – 2009
Earth’s viewpoint – map of Antarctic volcanoes
From the UW paper again:
“West Antarctica is a very different place than East Antarctica, and there is a physical barrier, the Transantarctic Mountains, that separates the two,” said Steig, lead author of a paper documenting the warming published in the Jan. 22 edition of Nature.
But no, it just couldn’t possibly have anything at all to do with the fact that the entire western side of the Antarctic continent and peninsula is dotted with volcanoes. Recent discovery of new volcanic activity isn’t mentioned in the paper at all.
From January 2008, the first evidence of a volcanic eruption from beneath Antarctica’s ice sheet has been discovered by members of the British Antarctic Survey.
The volcano on the West Antarctic Ice Sheet began erupting some 2,000 years ago and remains active to this day. Using airborne ice-sounding radar, scientists discovered a layer of ash produced by a ’subglacial’ volcano. It extends across an area larger than Wales. The volcano is located beneath the West Antarctic ice sheet in the Hudson Mountains at latitude 74.6°South, longitude 97°West.
UPDATE 1/22
In response to questions and challenges in comments, I’ve added imagery above and have a desire to further explain why this paper is problematic in my view.
The author of the paper himself (Steig) mentions the subglacial heat source in a response from “tallbloke” in comments. My issue is that they don’t even consider or investigate the possibility. Science is about testing and if possible, excluding all potential candidates that challenge your hypothesis, and given the geographic correlation between their output map and the volcanic map, it seems a reasonable theory to investigate. They didn’t.
But let’s put the volcanoes aside for a moment. Let’s look at the data error band. The UAH trend for Antarctica since 1978 is -0.77 degrees/century.
In a 2007 press release on Antarctica, NASA’s describes their measurement error at 2-3 degrees, making Steig’s conclusion of .25 degrees Celsius over 25 years statistically meaningless.
“Instead, the team checked the satellite records against ground-based weather station data to inter-calibrate them and make the 26-year satellite record. The scientists estimate the level of uncertainty in the measurements is between 2-3 degrees Celsius.”
That is from this 2007 NASA press release, third paragraph.
http://earthobservatory.nasa.gov/IOTD/view.php?id=8239
Also in that PR, NASA shows yet another satellite derived depiction which differs from the ones above. I’ve added it.
Saying you have a .25 deviation over 25 years (based on one-tenth of a degree Celsius per decade per Steig) with a previously established measurement uncertainty of 2-3 degrees means that the “deduced” value Steig obtained is not greater than the error bands previously cited on 2007, which would render it statistically meaningless.
In an AP story Kenneth Trenberth has the quote of the day:
http://news.yahoo.com/s/ap/20090121/ap_on_sc/sci_antarctica
“This looks like a pretty good analysis, but I have to say I remain somewhat skeptical,” Kevin Trenberth, climate analysis chief at the National Center for Atmospheric Research, said in an e-mail. “It is hard to make data where none exist.”
E.M.Smith (17:11:36) :
<blockquote: foinavon (16:10:53) : The correctness/reliability/usefulness of a paper really starts to be assessed once it appears in the literature. It stands or falls in relation to subsequent research, analysis and publications.
E.M.Smith: Odd that you left ‘replication’ off that list… Is that why we have not gotten publication of the raw data and methodology of GISS ?</blockquote?
The question of "replication" is implicitly addressed within "It stands or falls in relation to subsequent research, analysis and publications”. Scientific work is rarely “replicated” explicitly – but in progressing any work of significance, relevant elements, of course, are replicated. It’s far better for our understanding of natural phenomena that different groups address analyses using their own methodologies..that way one can assess the metholodogical-dependence of outcomes and interpretations, highlight incompatibilities between differrent analyses and assess likely bounds of reliability and such like…
For example (since these have been discussed on this thread!) , Mann et al’s paleoproxy study of 1998 spawned a whole series of subsequent paleoproxy analyses using different methods, and so we’re rather more confident of the essential conclusions now than we were then. The tropospheric satellite data analysis is independently analyzed by at least two groups. RSS are not explicitly “replicating” the UAH analyses, they’re analysing data using their own methodology. The global temperature anomaly evolution is determined by three different groups using different methods..there seems to be a pretty good condordance across the different analyses…..and so on…this is a far more productive means of progressing knowledge than what seems to me to be a rather narrow-minded and mean-spirited approach that asumes that scientific data is wrong and needs constantly to be “replicated”!
So I think one needs to be careful about what one means by “replication”…
It seems to me that GISS’ methodologies are defined in rather bottom-squirming detail in several publications.
foinavon at (11:54:32) posted the following nonsense:
“That may be “conventional wisdom” but it’s not what the science has shown! It’s been known for 25 years that the expectation for polar warming in response to an enhanced greenhouse..”
so where has the science shown this?
If the southern oceans are a thermal “sink” that “masks” warming, shouldn’t the sea surface temperature show an upward trend?
it doesn’t
It is not science if it does not explain the observations. It is hypothesis, conjecture and speculation.
wattsupwiththat (17:12:34) :
As someone who is sitting outside of this field (but a scientist who can access scientific data, read the scientific literature and make a reasonably informed analysis – I hope!), that just doesn’t seem to accord with sensible interpretation. I’m sure that Mann et al made some errors. I make errors all the time and very occasional minor errors creep into analyses which might subsequently be published. The question is whether these errors are of real substance that cloud reliable interpretation or (heaven forbid!) render the work inherently incorrect.
I would suggest that we can assess this rather objectively, particularly in hindsight, through the scientific process of follow up studies, scientific debate and publication. We can take Spencer and Christy’s work and read every paper that has cited these. It’s pretty clear that Spencer and Christy were very wrong for a period of 15 years. Their initial statistical analysis was inadequate and they introduced a series of spurious artefacts for years. These were repeatedly highlighted by others through the scientific literature. We know very well that their claim to precision was wildly incorrect, that their claimed cooling trends were in actual fact warming trends and so on…they got it completely wrong for a long time…
We can look at Mann et al’s 1998 study in the similar context of hindsight. As far as I can see the subsequent paleoproxy analyses demonstrate that Mann et al’s rather tentative interpretations was materially robust. All of the paleoanalyses support the interpretation that late 20th century and contemporary warming is anomalous in the context of the last 1000 years or more in the Northern hemisphere.
e.g. http://www.ncdc.noaa.gov/paleo/recons.html
It doesn’t seem to me that Mann has made any substantial errors to the extent that the analysis gives a false view of the available evidence. How can that be the case if pretty much all the paleoproxy data of the last 10 years leads us to broadly similar conclusions?
Mr V
No I haven’t read the study and I believe it is dodgy because you are quoting it! Simple enough for you?
What about the many studies that confirm the MWP? Have you read all of those? Let alone the documented historical evidence.
George E. Smith (17:37:42) :
What’s a “AGW fan”? The science is debated in research labs, at scientific meetings, in the scientific literature and other scientific arenas. We can do without these contrived set piece “debates” that shed very little light, and are very often a means for a paricular position to play to an audience.
Gore’s not a scientist is he? He’s a politician. I think we all know that. If I’m interested in the science I’d much rather address that directly. If I’m interested in policy, I’d be quite keen to speak with Mr. Gore.
It seems to me these calls for “debate” between scientists, and groups that have hived themselves off into a separate faction are inherently unproductive. The very fact of ring-fencing a position within science is anathema to sensible debate.
Of course I’m sure everyone will have fun at the Heartland meeting, and will come away feeling empowered and ready to take up the cudgels and so on…
Allan M R MacRae (18:39:54) :
Why not have a look at the papers Allan. For many years UAH pursued the fallacy that the tropospheric temperature trend was negative even ‘though we know that it’s positive. That’s not “an insignificant error” is it!
And as your web site link shows this spurious analysis was still being pursued in 2002.
And of course in 2005, the highlighting by others of yet another spurious cooling trend resulted in antoher 40% hike in the warming trend. That’s not “an insignificnat error” either is it..
whoops! Apols for the incompetent use of “blockquotes” in my messages foinavon (02:36:25) and foinavon (03:50:22). In the latter post, only the first paragraph of text in the bottom blockquote is George’s.
I think 100 miles is being pretty magnanimous. Try a half a world away!
Joel Shore (17:34:00) :
Perhaps “incompetent” is strong…I’m not sure.. But something very weird has gone on with the UAH analyses over the years. One doesn’t mind making mistakes, but it’s nice if one can indentify these oneself before repeatedly broadcasting deficient analysis, particularly when these are repeatedy in the “wrong” direction…perhaps we can at least say that there were a number of rather competent scientists that identified and highlighted the errors in the UAH analysis over the years.
Actually I don’t think it’s really a big deal now and perhaps one shouldn’t go on about it. But it’s worth highlighting the audacious and rather exhilarating double standard on this issue which I find fascinating. It’s this:
Mann et al. published their work in Nature and Geophys. Res. Letters in 1998/9. They were rather tentative in their conclusions and highlighted uncertainties in their analyses [The 1999 paper was titled: Northern Hemisphere temperatures during the past millennium: inferences, uncertainties, and limitations” (Geophys. Res. Lett. 26, 759–762; 1999)]. The uncertainty ranges in the Figures in both papers were very clear and very large and so on…
Christy and Spencer published their first analysis of MSU data in 1990 with an assertion of precision [Spencer RW, Christy JR (1990) Precise Monitoring Of Global Temperature Trends From Satellites. Science 247, 1558-1562] which we know to be completely unjustified, and was pointed out at the time.
In the intervening years the essential conclusions from Mann et al’s analysis have been supported by a number of other paleoproxies using different approaches, and as far as I can see we seem to be rather more confident about the relationship between current and past-millenial temperatures to the extent that these can be assessed from reconstructions from proxy series. For this Mann has been pilloried in a virtual industry of blog-based attack…
On the other hand, Christy and Spencer who basically got it rather badly and repeatedly wrong for a very long period are lauded in the same quarters.
What does all that mean? It certainly seems to me that there’s something that equates more to “heat generation” than an urge to understanding and knowledge advance going on there….but perhaps I’m not looking at these events in quite the right way….!
E.M.Smith (14:27:04) :
What do you mean by “Harvard and NASA” George? This is a conference abstract by a Czech scientist (Prague) presented at the International Solar Cycle Studies Symposium (ISCS 2003), June 23-28, 2003, in Slovakia.
In what sense do you consider the correlation “well-demonstrated”? After all the title is “Possible correlation between solar and volcanic activity in a long-term scale”.
This work was never published in the scientific literature. It’s a conference presentation. Generally if a study is of any significance it’s properly published. If one looks at the scientific papers by Dr. Strestik we can see that he looks for correlations between solar and natural phenomena:
e.g.: Strestik J et al. (2001) Variations in the mortality with respect to lunar phases Earth Moon and Planets 85-6, 567-572.
or: Mikulecky M, Strestik J (2007) Cerebral infarction versus solar and geomagnetic activity: A cross-regression study. Israel Medical Association Journal 9, 835-838.
That’s fine of course. But is there a correlation between solar activity and volcanic activity? I think we’d like to see the evidence.
Anthony quoted Trenberth:
“This looks like a pretty good analysis, but I have to say I remain somewhat skeptical,” Kevin Trenberth, climate analysis chief at the National Center for Atmospheric Research, said in an e-mail. “It is hard to make data where none exist.”
Actually, the problem is not that it’s ‘hard to make data where none exist.’ It’s that it is easy to do so.
That said, not having read the paper, I have no real problem with it up front. I think it’s more important to quote exactly the conclusions and uncertainties, caveats and hedges and to compare that with the press releases, headlines and the news reports. The ‘certainty’ and ‘consensus’ is found mainly in the reporting, not in the actual evidence and this disconnect, wherever it’s found, is what needs to be focused on rather than knee-jerk dissing of the scientists and their work.
The study itself will be analyzed by other scientists and statisticians and through that the science will/should be advanced.
As to the volcanic activity in the area, there is too much we do not know including the depth of the vulcanism and its relationship to the thermocline. If the thickness of the ice is on the order of 6000 feet, it doesn’t seem likely that the vulcanism is going to affect the surface temperature especially over this short period of time. But the flipside of that is that the heating of the surface isn’t going to affect the base of the iceshelves through that thickness either.
If the ice shelves break off, it won’t be due to CO2 then will it?
Where are the studies about this? Seems the grant money isn’t interested.
In any case, the oceans are proving much more important than previously thought.
I wonder what the opinion of this paper by the current set of defenders would have been if it started in 1940 and CONFIRMED antarctic cooling of 70 years.
I also wonder whether it would have been published at all.
Perhaps when AGW and the Big Bang are proven wrong, science can finally get out of a 15th century ‘believe what you are told’ mentality.
Looking at various web sites that describe the instrument used in this study (the USGS Advanced Very High Resolution Radiometer [AVHRR]), there are certain statements that may or may not have an impact on the data used in this study. Following, I have excerpted certain quotes that may raise questions about the data, although it is unclear from the descriptions whether or not the data used in this study is affected or not. Please refer to the complete description on the respective websites for context.
From http://edc2.usgs.gov/1km/paper.php:
Does this mean that there are gaps in the satellite data used in this study? It is hard to tell one way or the other from this description. Also, the statement that the main intended use of the data sets are related to surface vegetation cover raises the question of whether this instrument was designed to be used to measure temperatures in Antarctica, where there is essentially no vegetation. Again, this may or may not affect the data used in the study.
Is it possible that only afternoon data was collected and no nighttime data? If this is true, it would have a major impact on the credibility of the study. Unfortunately, one cannot tell from this description if this statement applies to the data used in the study.
Presumably, there is little water vapor and there are few aerosols over Antarctica, but maybe not. The fact that no corrections are made for water vapor and aerosols may or may not be relevant to the study.
From http://edc.usgs.gov/guides/avhrr.html:
The study states under “METHODS-Data” that the
The description from the above referenced AVHRR website may or may not be in conflict with the statement in the study in that night acquisitions may not have been requested for this time period and that data prior to March 1990 may be very incomplete. Again, it is difficult to tell whether these statements apply to the data in the study, but I think it is worth asking.
Phil. (21:25:25) :
Actually it isn’t ‘a fact of mathematics’, you appear to have confused accuracy with resolution.
No, I have not.
FROM: http://www.srh.noaa.gov/mlb/F6info.html
Temperature is measured electronically. High or low temperatures for the day may be estimated when necessary. Temperatures are measured in degrees and tenths fahrenheit, and reported as whole degrees, rounding down from .4 and up from .5
(I added the bold typeface)
The resolution of the instrument is in 1/10th degrees. This is then rounded to whole degrees. You no longer know if you measured (resolved) 76.5 or 76.9 or 77.4 degrees. Your accuracy is now in whole degrees. 77.
From this point onward, any math done with more precision than whole degrees is subject to false precision.
From: http://en.wikipedia.org/wiki/False_precision
False precision occurs when numerical data are presented in a manner that implies better precision than is actually the case; since precision is a limit to accuracy, this often leads to overconfidence in the accuracy as well.
Notice that the word ‘resolution’ does not appear… (in fact, it is nowhere in the whole page.) Once you cut the precision of the data to whole degrees you also limited the accuracy to whole degrees.
We also have:
For example, if one instrument can read to tenths of a unit of measurement, calculations related to data obtained from that instrument can only be confidently stated to the tenths place, regardless of what the raw calculation returns or even if other data used in the calculation can be obtained more precisely.
Which also means that once you have buggered your original resolution down to whole digits of precision (thus reducing accuracy to whole digits) you can never recover precision greater than whole digits since that would lead to false precision.
If a new instrument, say a satellite or automated station, now reports in 1/10th of a degree or even 1/100th of a degree you can not mix that data in with any of the old data reported in whole degrees unless you truncate your precision at whole degrees. Otherwise your precision is false and your results assert an accuracy that is not there.
Thus, since for most of the temperature record there is whole degree or less precision, any claim that the world is changing by tenths of a degree in any direction is just bogus.
I will refrain from comment about what the degree or two ‘adjustments’ done to the data by GISS does to any assertions of precision or accuracy…
You might want to also read:
http://en.wikipedia.org/wiki/Accuracy_and_precision
which is also devoid of the word ‘resolution’…
E.M.Smith (12:10:49) :
Phil. (21:25:25) :
“Actually it isn’t ‘a fact of mathematics’, you appear to have confused accuracy with resolution.”
No, I have not.
You have yet again!
Systematic errors → accuracy
How close mean of measured values is to true value
Random errors → precision
Repeatability of measurements
Characteristics of tools → resolution
Smallest increment between measured values
“In the intervening years the essential conclusions from Mann et al’s analysis have been supported by a number of other paleoproxies using different approaches, and as far as I can see we seem to be rather more confident about the relationship between current and past-millenial temperatures to the extent that these can be assessed from reconstructions from proxy series. For this Mann has been pilloried in a virtual industry of blog-based attack…”
You can’t be serious. Mann has not been “pilloried,” he’s been audited; along with the other Team members proxy studies that have used exactly the same false proxies that Mann was told by NAS not to use. Every one of these studies have been shown to be statistically inept, not to say, incompetent. For you, as a “scientist,” to blandly make these statements shows, to me, an appalling non-familiarity with the state of play on these questions. You need to go to Climateaudit.org and read the history. If you disagree with McIntyre then show him where he is wrong, but don’t come here and asssume we don’t know what the story on the Team is.
Fionhaven
You and your kind really worry me. Satellite temps from Christy and Spencer are always disparaged by the “Team”, and I include you in the team, because you all come out to play together whenever you feel there is a threat to your “virtual domain” of AGW. Why are you so concerned?
Here you and all your friends are having great difficulty measuring the Earth’s temperature from six feet above the ground and yet you can’t wait to denigrate measurements from space. I would suggest that if their minor errors were on your side of the fence Christy and Spencer would be receiving kisses all round. Instead we have Mann’s et al “interpolation” of satellite data which you prefer. No wonder I don’t believe a word you say. Anybody who defends Mann destroys their credibility as a scientist.
Phil H:
It’s becoming obvious that the Team lives in its own little bubble: click
Simon Evans (22:29:59) :
2. E.M. Smith: “Your accuracy is measured in degrees. There can be no precision that is valid in less than full degree increments. There can be no trend of less than full degrees.” Those are your premises and not mine, so there is little point in demanding whether I accept the conclusion you draw from them.
See my prior post with citations. These are not my premises, (in fact, they are not ‘premises’ at all, they are methods), these are the standard ways of doing math in science and engineering. It ought to have been taught to you in high school chemistry or physics class. (Though I remember my H.S. math teacher covering it as well.)
Yes, it shakes the foundation of the AGW argument (it also shakes the foundation of the skeptics argument). Folks just don’t want to hear that we do not know and can not know more precisely than whole degrees; but that is all the historical data support. If you wanted to go back and throw out all data recorded in whole degrees and only use data recorded in fractional degrees, then you could have more precision. but I suspect that would be a very small data set.
Sidebar: Since the GISS data report the ‘average’ temperature on a day, I would love to see the raw data (I’ve got my hands on the FORTRAN now and I’m working through it…). IFF the raw data has whole degree high and low that are then averaged to fractional degree averages, that is a fatal error.
Taking 78 + 23 = 101 / 2 = 50 is fine, but making it 50.5 adds precision and implies accuracy that is not there. It could be 50. It could be 51. You don’t (and can’t) know.
(The limits of the original temperatures read are 77.5 + 22.5 = 100 / 2 = 50 and 78.4 + 23.4 = 101.8 / 2 = 50.9 assuming the reading was right, but you don’t know where reality is in that range…)
From here on down I’m going to indulge in some speculation:
IF these tenths laden average numbers were then used to compute the adjustments to other numbers (giving even more spurious tenths…) all you can say with certainty is that you can say nothing with certainty in the tenths range.
IF those ‘corrections’ extend beyond the tents via a math step amplifying the tenths, then the whole degrees start to be suspect. (For example, if a spurious 1/2 degree rise at a location is amplified by a spurious 1/2 degree UHI adjustment from a different spurious 1/2 degree station into a 1 degree rise, the whole degree is fictional… Similarly, if the 50.5 from above were calculated then ’rounded up’ to 51 in a mistaken belief that this was getting the precision back in line, you again have amplified the error in the tenths place…)
The only ‘premise’ or assumption I’m making in all this is that the NOAA page cited in my prior post is correctly representing the precision of the recorded raw data used by GISS. If there are some other, more precise data (i.e. if the raw with 1/10ths from land stations is somehow recorded) they would allow more precision (though if averaged in with any ‘old’ full degree data the precision drops to full degrees…)
And this might explain why the satellite data (which I presume are reported in more precision than whole degrees…) diverge from the GISS.
In fairness to GISS, the basic error may originate with NOAA. I notice on the form that they report the average and departure in tenths. IFF GISS is depending on a NOAA provided average with tenths, then the fault is with NOAA…
They are liars. The 30 year sat record shows no such thing.
http://climate.uah.edu/maps/30yrbig.jpg
foinavon (06:21:44) :
E.M.Smith (14:27:04) :
Per ‘the volcano did it’, will Harvard and NASA do?
http://adsabs.harvard.edu/abs/2003ESASP.535..393S
States that there is a well demonstrated correlation of more volcanism with solar minima and less with solar maxima.
What do you mean by “Harvard and NASA” George? This is a conference abstract by a Czech scientist (Prague) presented at the International Solar Cycle Studies Symposium
It wan’t George, it was me. Harvard is in the link, and NASA is in the header as “SAO/NASA ADS Astronomy Abstract Service”. I presume they deal with real scientists and real science… Or do you find something wrong with Czech science?
In what sense do you consider the correlation “well-demonstrated”? After all the title is “Possible correlation between solar and volcanic activity in a long-term scale”.
Well, perhaps when they say “striking similarity” and “indubitable” it means something? Yes, the title says “Possible” as do a very large number of folks when presenting work. So? Never heard of modesty? I’ve added a bit of bold to make it easier to spot was was in the body of the text.
“Using 21-yr running averages a striking similarity between these two time series is clearly seen. Volcanic activity is generally lower in periods of prolonged maxima of solar activity and higher in periods of prolonged solar minima. There is also a similarity between the spectra of these two series in the long-period range. Main peaks are located in the same periods in both series (200-215 yr, 100-105 yr, 80-90 yr). The influence of volcanic activity on the climte is indubitable.
There were lots of others papers that showed up in the google search, this isn’t unique. I mostly picked it because it was short and direct. If you don’t like it you can go find many more with the same conclusion.
foinavon says:
Oh, I think it is absolutely worth highlighting and I appreciate your posts on this as I learned some new things (such as the audacious title that Spencer and Christy gave to their first paper on the satellite measurements).
While I thought “incompetent” might have been too strong a word, I think “double standard” is probably too weak a word for what you describe! I am also amused how small errors discovered in the GISS temperature record (such as the Y2K error or the October 2008 error) that make essentially no difference to the global temperature trend (over any period long enough that it can be reasonably determined) are considered to be a huge deal whereas people like Lee Kington or Allan M R MacRae seem to believe that the UAH errors that got the sign of the temperature trend wrong are “minor” or “practically insignificant”!
Phil Howerton says:
And, these “audits” have been published in the peer-reviewed literature where exactly? If McIntyre & co. had the confidence in these “audits” he would put them out in the peer-reviewed literature for consideration by the scientific community. So far, it appears that he has primarily used them to preach to the converted.
And, why did the NAS report not come to the conclusions that you are reaching? In order to pull out something you like from it, you have to take one sentence in that entire report and use it to reach a conclusion quite different than the conclusion that the report actually reached? (Besides which, I don’t think it is even true that all the other studies have used the strip-bark trees…and at least one report has tested the sensitivity of their results to the removal of up to (any) two or three of the proxies used.)
Phil. (12:55:35) :
E.M.Smith (12:10:49) : No, I have not.
You have yet again!
I’ll try once again:
Characteristics of tools → resolution
Smallest increment between measured values
Which is agreed. It was in 1/10th degrees. Never said otherwise.
Random errors → precision
Repeatability of measurements
Here you start to drift. You leave out the mathematical precision. The data from the resolution step are rounded to full degrees. At this point the precision becomes full degrees. One measurement may give 77.4, the next 77.5 at the same 7.4445 real temperature (precision and repeatability of 1/10ths) but once you have turned those two numbers into 77 and 78 in the record, the repeatability in 1/10ths is gone. If you remeasured you might get 77.4 or 77.5 (still 1/10s range of repeatability in the device) but the rounding magnifies this into 77 or 78 (full degree range of result). Your ‘repeatability’ is now measured in full degrees. You have a one degree ‘random’ error in your data from a 1/10th variation in your instrument.
Your precision is now full degrees, since you have a full degree of variance (error) in your data from ‘equivalent’ measurements at 77.4445 degrees real.
Systematic errors → accuracy
How close mean of measured values is to true value
And here is the next drift. It isn’t just ‘measured’ values at this point. It’s the recorded values. Your instrument was left behind at the rounding stage above…
So if the real value is 77.4445 and I can get 77 or 78 from it in the record, my accuracy range is 1 degree. .4445+.5555=1.0000 That is what is meant in the pages I cited when they said the precision limits the accuracy… Please re-read the citation if you need more clarity on this point.
(And before you run off to say that the mean of 77 and 78 is 77.5, realize that my data record could contain a series of 77’s with a mean of 77 or a series of 78s with a mean of 78 from a series of 77.4445 temps recorded with a 77.x instrument rounded to 7X so the mean depends on the actual data series and has a range of 1 degree possible. Actual +/- 0.5 degree.)
If you want to keep playing ‘does so / does not’ at this point, I give up. Go read the literature.