Tom Karl’s Trends Are Wrong – At Least in Slide 21
Guest post by Bob Tisdale
A number of bloggers on the WattsUpWithThat thread “Tom Karl’s Senate Dog & Pony Show – it’s worse than we thought, again” noted the curious errors in the trend lines in Tom Karl’s presentation to Senate. The one that stood out for me was slide 21, presented here as Figure 1. It showed the global land surface temperature anomalies and linear trends for the new (Version 3) versus existing (Version 2) Global Historical Climatology Network (GHCN) dataset.
http://i48.tinypic.com/4j4c60.png
Figure 1
First Observation: The slide title states the data is monthly, but the data illustrated are annual averages. Figure 2 is a graph of monthly Global Land Surface Temperature anomalies presented by the NCDC from January 1900 to April 2010. Monthly global land surface temperature anomaly data should look like that, with lots of month-to-month variation.
http://i45.tinypic.com/5k3xjp.png
Figure 2
Second, there are two linear trends listed on the Karl slide. Version 2 is noted to have a linear trend of 0.83 deg C/Century, while Version 3 is claimed to have a linear trend of 0.91 deg C/Century. But the trend lines are nearly identical and they present linear trends of approximately 0.75 deg C/Century, Figure 3. The trend lines are erroneous or the values listed for the trends are wrong.
http://i49.tinypic.com/28iyyhk.png
Figure 3
Trend lines of 0.83 and 0.91 deg C/Century should be noticeably different, as shown in Figure 4.
http://i48.tinypic.com/346at1d.png
Figure 4
And for reference, the NCDC’s Monthly Global Land Surface Temperature anomaly data, Figure 5, has a linear trend of 0.78 deg C/Century.
http://i47.tinypic.com/142a1b4.png
Figure 5
And the the NCDC’s Annual Global Land Surface Temperature anomaly data, Figure 6, has a linear trend of 0.77 deg C/Century.
http://i45.tinypic.com/v4qvxl.png
Figure 6
Makes one wonder. If a simple comparison graph with linear trends is so error filled…
SOURCES
Tom Karl’s Powerpoint Presentation is available here:
ftp://ftp.ncdc.noaa.gov/pub/download/Global%20Warming%20is%20Unequivocal%20TKarl%20May%206.ppt
A full-sized copy of Slide 21 is here:
http://wattsupwiththat.files.wordpress.com/2010/05/karl_senate_2010_pg21.png
The NCDC Land surface temperature anomaly data is available through the KNMI Climate Explorer:
http://climexp.knmi.nl/selectfield_obs.cgi?someone@somewhere
0 comments:
Discover more from Watts Up With That?
Subscribe to get the latest posts sent to your email.
At the start of the Graph the year 1990 was it -0.4c below a.v.g then and if so how do they come up with that Temp?.
With regards to UHI, it would be interesting to analyse an urban area’s total energy usage in terms of watts/sq.m. Electrity, gas, oil (even wood), petrol and diesel – all usage immediately or ultimately heats the air. Could be a conclusive way of countering the argument that UHI contributes little to urban temperature measurements.
Mark.R says:
May 20, 2010 at 2:35 am
At the start of the Graph the year 1990 was it -0.4c below a.v.g then and if so how do they come up with that Temp?.
SHOULD SAY 1900.
AGW is real – its official – and so is anthropogenic sea level rise. Robust proof of this is easy: tape together two yard (meter) sticks and go to your nearest surfing beach. Wade out to waist depth, and measure the depth during the trough between two waves. Then as the crest of a wave moves over you, meaure the depth again, taking care to remain vertical.
The difference in height will prove sea level rise beyond reasonable skepticism. Better clean the sand off those yardsticks and hurry up with my ark building – its worse than I thought!
Locally cached on your PC maybe? I even saved the png image to HD and re-loaded the image by itself using IE6/Win98SE.
Maybe it is this PC (YABC – yet another backup computer) – will try a Win2000 platform w/Opera.
.
.
Addenda; it’s loading on this platform now (IE6/Win98SE) …
Mark.R asked: “At the start of the Graph the year 1990 was it -0.4c below a.v.g then and if so how do they come up with that Temp?”
They present the temperatures of what little data they have on record. For example, here’s a map showing the locations of the land surface temperature station readings for the year 1900 that were used by the Hadley Centre in their CRUTEM product:
http://i46.tinypic.com/315oas7.png
I cant understand why anyone is obsessing over quality of the regression and hence the slope of the graph when it is obvious that the whole slope is determined by the temperatures in the 1900 to 1940s period, before anthropogenic CO2 was an issue, and hence the whole slope of this graph is irrelevant to the AGW story. If this graph is supposed to show a link between CO2 and warming, it shows exactly the opposite. It clearly shows the warming trend was established in the late 1900s. I would have thought to see a CO2 trend you have to take that slope off and look at the residual.
Alvin says:
May 19, 2010 at 7:58 pm
Will someone be able to pose the error to the Senate?
Not in your lifetime.
All this demonstrates to me the futility of using straight lines of any sort when considering graphical representations of climate variations. Over the short term (years, decades) they are meaningless because of the ability to select start and end points to suit an argument, and are even worse as predictors of future variations, and worse still at recognising any simple or complex cyclic variation.
They do however have impact as marketing tools, especially when aimed at the lay public, and I suggest this is why they are so popular with the global warming industry.
Mike: You wrote, “Linear regressions are done on the data, not by putting a ruler on a crude graph from a power point slide.”
Apparently the obvious eludes you. If, when the linear trend line crosses the x-axis at the year 1900, the temperature anomaly on the y-axis is “x” degrees C, and if it crosses the hash mark at the year 2000 (one century later) with the temperature anomaly of “x” plus 0.75 degrees C, what is the linear trend per century?
Alvin: You asked, “Will someone be able to pose the error to the Senate?”
As of 9:00am eastern, I’ve only had three visitors from the Washington D.C. area open this post on my website. But my website gets a bajillion fewer hits per day that WUWT. If I get a hit from the Senate Office Buidling today, I’ll let you know.
Seems to me that we’ve recently been educated that applying a linear trend to a data series with a unit root is completely meaningless. Not only that, but if one starts the trend at 1880 instead of 1900 the warming will be the same and the meaningless trend will be lowered.
Someone who would present this kind of bogus analysis to Congress is essentially lying. Will Karl be prosecuted?
Mike G says:May 19, 2010 at 9:36 pm
Now would be a good time to link to the various blink comparisons showing the first half of the 20th century before they removed its inconvenient warmth, for Mike’s benefit.
Here you go: http://i42.tinypic.com/vpx303.jpg
Notice the past is not only reduced, post 1960’s goes up. Pinning the graph at the mid 60’s and rotating 6° CCW makes the new representation. This was revealed by someone here at WUWT recently.
Bob Tisdale says:
May 20, 2010 at 1:05 am
Basil says: “I have a problem with Figure 4. Linear trends go through the point of means.”
Figure 4 was presented as an example to show that the differenes between the trends of 0.83 and 0.91 deg C/century would be visible.
But it is still wrong, and presents a misleading result. If you have the lines intersect in the middle, as they should, then at the end of the period covered by the graph, the difference will not be as great, or as visible, as you’ve shown. Roughly (because the two trends are so close together), the difference be about one half what you’ve shown.
If we are going to criticize erroneous or gee whiz graphs with the warmistas use them, we need to hold ourselves accountable to such criticism as well.
I understand your main point, and agree. The original chart hardly seems to support the claim attributed to it. To those who criticized your method of calculating a .75 slope — “by putting a ruler to the paper” — I would defend your method. You didn’t create the trend line. You just measured what it shows, and with a defensible approach.
Responding to:
AC of Adelaide says:
May 20, 2010 at 4:30 am
I cant understand why anyone is obsessing over quality of the regression and hence the slope of the graph when it is obvious that the whole slope is determined by the temperatures in the 1900 to 1940s period, before anthropogenic CO2 was an issue, and hence the whole slope of this graph is irrelevant to the AGW story. If this graph is supposed to show a link between CO2 and warming, it shows exactly the opposite. It clearly shows the warming trend was established in the late 1900s. I would have thought to see a CO2 trend you have to take that slope off and look at the residual.
It is not obvious that the slope is determined by 1900 through the 1940’s. Linear regressions are heavily weighted toward the end points of the data. In this case, I’d say that the slope is very much influenced by the much higher trend from 1960 to 2010. If the slope of those years had been the same as the slope of the years from 1900 to 1940, the trend would basically have been flat. It is as positive as it is because of the more rapid growth in the second half of the 20th century. Now, that more rapid growth is partly bogus, in that it starts measuring during a cool period, i.e. 1940-1960.
I agree with the point that warming that began before the middle of the 20th century tends to undercut the AGW hypothesis. But if I were a proponent of AGW looking at that graph, I’d see — since human nature is to see what we want to see — that the trend from 1960 to 2010 was about twice what it was from 1900 to 1940. And then I’d say, okay, the earlier warming was natural, and the doubling of the rate in the second half of the 20 century is evidence of AGW. Which is pretty much the exact claim that was made in AR4. So it behooves anyone challenging AGW to answer that claim. Part of the answer is that the higher growth of the second half of the 20th century is inflated by measuring growth from the low point of a cold phase of a PDO to the high point of a warm phase. But I’m not sure that is the whole story. This last warm phase of the PDO (i.e. the period since “The Great Climate Shift of 1976” seems to have been unusually warm. I don’t think CO2 can explain it. But I don’t think it can be denied, either. Science still has a lot to learn about the forces that control and govern natural climate variation. One thing we all ought to know, thanks in the main to Roy Spencer and w., is that the proper null hypothesis of natural climate change has yet to be rejected.
P.S.
Some of the “inflation” of the growth rate in the latter half of the 20th century is probably do to data quality control issues. I’m not denying that. But I do think the last warm phase of the PDO was unusually “robust,” based on the frequency and strength of the El Nino’s of that period.
Thomas says:
May 19, 2010 at 8:31 pm
“….One century ago children died at alarming rates, mostly from biologically polluted water, famine was common place, and virtually no one had electric lights, air conditioners, automobiles, jet planes, computers, telephones, cell phones, microwave ovens, washers and dryers, flush toilets, sewage treatment plants, water purification plants, etc., etc.
We should be concentrating on improving the lot of those of us who still go to bed hungry, and who don’t have all the wonderful things we take for granted. In fact, shame on AGW advocates for taking attention away from that effort. We should be building power plants and infrastructure in the developing world, not trying to figure out how to make our power plants more expensive….”
_____________________________________________________________________
Thomas, you missed the whole point. AGW advocates want to turn back the clock to a time when serfs died like flies and the aristocracy had absolute control. It is all about greed and power.
“Here, in his own words, is what Strong wants for the middle class: “It is clear that current lifestyles and consumption patterns of the affluent middle class—involving high meat intake, consumption of large amounts of frozen and convenience foods, use of fossil fuels, appliances, home and work-place air-conditioning, and suburban housing—are not sustainable. A shift is necessary towards lifestyles less geared to environmentally damaging consumption patterns.” (1992 Rio Earth Summit 11).”
http://romanticpoet.wordpress.com/2010/05/14/maurice-strong-and-george-soros-world-wizard-and-financier-personified/
“…It would have been impossible for us to develop OUR PLAN for the world if we had been subjected to the lights of publicity during those years. But, the world is now more sophisticated and prepared to march towards a World Government. The supranational sovereignty of an intellectual ELITE and World Bankers is surely preferable to the national auto – determination practiced in past centuries.” – David Rockefeller – June 1991
“In politics, nothing happens by accident. If it happens, you can bet it was planned that way.” – Franklin D. Roosevelt
Here you go: http://i42.tinypic.com/vpx303.jpg
There is no source for this data on the graph.
What temperature series were used to produce this excellent blink chart?
Mike G says:
May 19, 2010 at 9:36 pm
Now would be a good time to link to the various blink comparisons showing the first half of the 20th century before they removed its inconvenient warmth, for Mike’s benefit.
__________________________________________________________________________
Mike you mean these:
Hansen changes the data: blink graphs
US temp raw vs adjusted
Lucy’s super blink graphs
In this article: Lamb’s temperature graph presented in first IPCC report in 1990
The measurement error is so big that if you put in the error bars they would swamp any trends:
A J Strata’s look at Cru e-mails on temp data error
Mr. Karl just needs to go back and robustify his data.
How does all them mega temperature of point six, or .8, or point seven, or .nine, or what, go from kelvin to fahrenheit to celsius with a 1:1 conversion?
Or does it just exist so many different temperatures and time series starting at different times these days that they just get confused? Maybe they just pick one from the heap, adding the scale and time that’s hyped for the day?
Jay Cech says: May 20, 2010 at 8:22 am
There is no source for this data on the graph.
What temperature series were used to produce this excellent blink chart?
It is GISS.
Basil says:
May 20, 2010 at 7:40 am “It is not obvious that the slope is determined by 1900 through the 1940′s. …….”
Dont agree. the rising trend 1902 to 1940 is actually steeper than the whole trend line and establishes the whole basis for the future trend
On the other hand I agree up to a point about your second observation. But not 1960. If you seriously want to identify a CO2 component you really need to analyse the graph in two sections – one pre 1944 (before CO2 kicks in) and one post 1944. I believe 1944 is taken as the magic date. I dont know how they use this graph but its crap.
In any case since the “Show this to Jim then hide it” disgrace I have no confidence in any graph that is constructed from “raw” data. I prefer to look at the early IPCC graphs before the usual suspect got their hands on the data.
Thanks Gail Combs and others. I always have trouble finding those things when I want to show them to somebody. Now, I’ve bookmarked them (again).
That other Mike. I doubt they would help him.
Basil: In reply to your May 20, 2010 at 7:40 am comment, a correction has been made at the version of the post at my website and you have been thanked.
http://bobtisdale.blogspot.com/2010/05/tom-karls-trends-are-wrong-at-least-in.html
Well it seems this place is crawling with Kiwi posters; if Fitzy and James Allison are also from that crusty side of the Pizza. I see that my latest issue of “Ingenio” says that one Mark Sagar was responsible for that blue faced idiocy that passed for Aliens on that highly political Avatar rubbish. I can abide Lord of the Rings seeing as someone wrote a book; but NZ should dis-associate itself from the silly Avatar like message; before people think, we are all kooks.
Am I to understand that NIWA actually determines the Temperature of NZ from 7; or is it 8 owl box stations. Why so many; why not just put one owl box at the top of Rangitoto, and take its reading as a good average for the whole country. I would almost bet that such a reading would be equally as valid (or invalid) as a sampling of 7 or 8 stations would be. Don’t they teach the Nyquist Sampling Theorem down there anymore ?
And I wouldn’t worry about any runaway climate problems down there; why the hell do they call the place Aotearoa ? No chance you chaps are ever going to fry like Venusians; maybe the Aussies will; but then they deserve it. I mean anyone who speaks English even lazier than the Kiwi do; deserves to fry. Well all but my sister; who still has an NZ accent, and not onoe of those “wash your fice in a bison.” twangs.