The recent paper Compo et al (2013) is titled “Independent confirmation of global land warming without the use of station temperatures”. It’s in the preprint phase, and of course it’s paywalled. The abstract is here. It reads:
Confidence in estimates of anthropogenic climate change is limited by known issues with air temperature observations from land stations. Station siting, instrument changes, changing observing practices, urban effects, land cover, land use variations, and statistical processing have all been hypothesized as affecting the trends presented by the Intergovernmental Panel on Climate Change and others. Any artifacts in the observed decadal and centennial variations associated with these issues could have important consequences for scientific understanding and climate policy. We use a completely different approach to investigate global land warming over the 20th century. We have ignored all air temperature observations and instead inferred them from observations of barometric pressure, sea surface temperature, and sea-ice concentration using a physically-based data assimilation system called the 20th Century Reanalysis. This independent dataset reproduces both annual variations and centennial trends in the temperature datasets, demonstrating the robustness of previous conclusions regarding global warming.
In short, Compo et al (2013) recreated global land air surface temperatures without surface station-based temperature measurements. Basically, they used other variables as inputs to a computer reanalysis to infer the land surface air temperature anomalies.
Of course, SkepticalScience has already written a post about the paper, in which Dana1981 throws in his two cents about the significance of Compo et al (2013). SkepticalScience was kind enough to post Figures 1 and 2 from Compo et al (2013). The Compo et al Figure 1 is included here as Figure 1. It illustrates the warming of land surface air temperatures from 1901 to 2010 for the latitudes of 60S-90N. The blue curve is the Compo et al reanalysis. The red curve is the new and improved CRUTEM4 data from the UK Met Office. And the black curve is the average of other land surface air temperature reconstructions, including NCDC, GISS, JMA, and UDEL.
Figure 1 (Figure 1 from Compo et al (2013))
What stands out for you in that graph?
For me, compared to the other datasets, the Compo at al reanalysis has warmer anomalies during the early-to-mid 1970s and cooler anomalies during the late 2000s, which would create a lower trend during the recent warming period. The Compo et al reanalysis also shows a flattening of land air surface temperature anomalies starting in 1995, where the other datasets show a continued warming. Compo at el also show an exaggerated spike in 1943 associated with the multiyear El Niño then. And Compo et al show a later start to the rise during the early warming period.
The choice of 1981-2010 as the base years for anomalies is also a curiosity. While the WMO recommends updating base years periodically, global temperature anomaly data producers such as GISS, NCDC and UKMO use their individually selected base periods.
REPLICATED COMPO ET AL REANALYSIS GRAPH
Using the coordinates function of MS Paint, I replicated the Compo at el (2013) reanalysis output. It’s compared to CRUTEM4 data for the latitudes of 60S-90N in Figure 2, using the base years of 1981-2010. (The CRUTEM4 data is available through the KNMI Climate Explorer on a gridded basis.) I’ve also included the linear trends. My replica produces a linear trend that’s comparable to the 0.09 deg C/decade trend noted in the SkepticalScience post.
Figure 2
So let’s take a closer look at the recent warming period, and we’ll start the recent warming period in 1976. Figure 3 compares the replicated Compo et al reanalysis to CRUTEM4 data for the shorter term. As suspected, the CRUTEM4 data shows a 32% higher warming trend than the Compo et al reconstruction. The flattening of the warm peaks in the Compo et al reanalysis since 1995 is also much clearer.
Figure 3
USING DIFFERENT BASE YEARS
In Figures 4 and 5, long-term comparisons, I’ve compared the CRUTEM4 and Compo reanalysis using the standard UKMO and GISS base years. Figure 4 shows the UKMO base years of 1961-1990 and Figure 5 shows the GISS base years of 1951-1980. The recent divergence (flattening of the warm peaks in the Compo et al reanalysis versus the continued warming of the CRUTEM4 data peaks) stands out quite clearly in both illustrations. I’ll let you comment on why Compo et al (2013) presented the anomalies using the base years of 1981-2010.
Figure 4
####################
Figure 5
TREND MAPS
My Figure 6 is Figure 2 from Compo et al (2013). Note the differences in trends over Alaska and the mid-to-high latitudes of Russia for the period of 1952-2010 (Cells c and d). Compo et al (2013) could not reproduce the excessive rates of warming there during that period.
Figure 6 (Figure 2 from Compo et al (2013))
CLOSING
Sometimes I get the impression SkepticalScience is unable to read time-series graphs. I’ll let you comment on the rest of the SkepticalScience post.
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And somewhat on topic, I’ve posted the full March sea surface temperature update, for those interested:
http://bobtisdale.wordpress.com/2013/04/08/march-2013-sea-surface-temperature-sst-anomaly-update/
Independent confirmation of global land warming without the use of station temperatures
“Confidence in estimates of anthropogenic climate change is limited by known issues with air temperature observations from land stations. Station siting, instrument changes, changing observing practices, urban effects, land cover, land use variations, and statistical processing have all been hypothesized as affecting the trends presented by the Intergovernmental Panel on Climate Change and others.”
William: The abstract incorrectly outlines the issue. The extreme AGW theory fails as there is no observed warming in the tropical troposphere at around 10 km, which the theory predicted and which is required for there to be amplification of the CO2 forcing. The extreme AGW theory fails as atmospheric processes are different what was assumed in the theoretical general circulation models. Likely the lack of warming in the tropical tropospheric regions is due to Lindzen and Choi’s finding that clouds in the tropics increase or decrease in the tropics to resist forcing changes, negative feedback. I find it difficult to imagine how it is possible to ignore the multiple observations and analysis that invalidates the extreme AGW theory.
A scientist, as opposed to a fanatic, changes their mind when the data no longer supports the theory. Those pushing the extreme AGW paradigm are having a very difficult time accepting the fact that observations and analysis does not support the extreme AGW theory.
The extreme AGW theory is dead, defunct, invalidated.
The attempt to show the planet is warming when it is not, is the work of fanatics who have a hidden agenda, not scientists. Compo et al (2013) is following in the tracks of Allen and Sherwood (See links below), in that they are trying by analysis to review the defunct, invalid extreme AGW theory.
http://icecap.us/images/uploads/DOUGLASPAPER.pdf
A comparison of tropical temperature trends with model predictions
We examine tropospheric temperature trends of 67 runs from 22 ‘Climate of the 20th Century’ model simulations and try to reconcile them with the best available updated observations (in the tropics during the satellite era). Model results and observed temperature trends are in disagreement in most of the tropical troposphere, being separated by more than twice the uncertainty of the model mean. In layers near 5 km, the modelled trend is 100 to 300% higher than observed, and, above 8 km, modelled and observed trends have opposite signs. These conclusions contrast strongly with those of recent publications based on essentially the same data.
Robert J. Allen & Steven C. Sherwood try to convince people of tropical tropospheric warming by analyzing winds speeds. Direct measurement and satellite measurement indicates there is no warming of the tropical troposphere in the regions predicted by the IPCC general climate models. There also is no evidence of warming in the tropics.
http://www.nature.com/ngeo/journal/v1/n6/full/ngeo208.html
Warming maximum in the tropical upper troposphere deduced from thermal winds
Climate models and theoretical expectations have predicted that the upper troposphere should be warming faster than the surface. Surprisingly, direct temperature observations from radiosonde and satellite data have often not shown this expected trend. However, non-climatic biases have been found in such measurements. Here we apply the thermal-wind equation to wind measurements from radiosonde data, which seem to be more stable than the temperature data. We derive estimates of temperature trends for the upper troposphere to the lower stratosphere since 1970. Over the period of observations, we find a maximum warming trend of 0.65 0.47 K per decade near the 200 hPa pressure level, below the tropical tropopause. Warming patterns are consistent with model predictions except for small discrepancies close to the tropopause. Our findings are inconsistent with the trends derived from radiosonde temperature datasets and from NCEP reanalyses of temperature and wind fields. The agreement with models increases confidence in current model-based predictions of future climate…
http://climateaudit.org/2008/04/26/tropical-troposphere/
Since they aren’t using land based temperature measurements, why aren’t they also comparing their results to the satellite data? I, for one, would like to see that chart for the past 33 years. That will tell us much more than their comparison to CruTemx!
Bill
Well, at least their reanalysis has not disappeared the pause that falsifies all AR4 GCM predictions.
If part of the premise of this work is to call into question air temperature measurements, you would have to call into question the measurements that were used to infer temperature. Really. Seems to me like we are trying to split hairs with a rather dull meat cleaver.
Guys at sks are preoccupied with the “big picture”, they prefer not to putter about factual details (like actual scientists do). It’s a judgement based on genuine personal experience there.
They reckon science is about impressions evoked by pictures somehow, not truth value of propositions having a strict logical structure. This “holistic” approach is characteristic of all varieties of pseudoscience.
Not sure how things like barometric pressure and other atmospheric parameters wouldn’t be affected by urban heat islands themselves. I think back in the 60s or latest the 70s, research directly tied UHI to changes in rainfall patterns around places like St. Louis and Atlanta.
“We have ignored all air temperature observations and instead inferred them from observations of barometric pressure, sea surface temperature, and sea-ice concentration using a physically-based data assimilation system called the 20th Century Reanalysis. This independent dataset…”
————————————————————————–
1) Is pressure independent of temperature ?
The thermal equation of state says otherwise, making pressure as much dependant on siting issues as temperature.
p*V = n*R*T
2) What sea ice concentrations are used before the satellite era ? The usual suspect, an almost constant value pre 1979, would be in contradiction to multiple historic reports.
3) Sea surface temperature has its own issues, among others the disturbing overwriting of post 1941 data
http://climateaudit.org/2011/07/12/hadsst3/
The Cobe-SST appears to be free of that issue, resulting in an increase of just 0.3 deg since the last natural, cyclical high around 1940 and about equal increases in 1910-1940 and 1976-2005.
http://www.ipcc.ch/publications_and_data/ar4/wg1/en/figure-3-4.html
I know my comments are going to annoy just about everybody who knows me – a small circle that – and, uh, just about everybody who doesn’t. But this following statement by Compo et al (2013) has required, compelled, forced (and every other coercive sounding verb I can think of), a response out of my typing finger:
‘We use a completely different approach to investigate global land warming over the 20th century. We have ignored all air temperature observations and instead inferred them…’
Ok, first: full disclosure. I went to an all boys high school. A Catholic high school. An all boys Catholic high school. So I suffer from a repressed memory syndrome. And the memory that is completely unsuccessfully repressed is the memory of never getting any dates. With girls. Ever.
Now, this was back in the late sixties and early seventies when everybody endeavored to ‘find themselves.’ Now, like every kid in school I associated ‘finding myself’ with sex, and drugs, and rock and roll. Unfortunately, that’s not the way the priests viewed it. No. Catholic school; remember? They viewed ‘finding ourselves’ as by inventing a new, expressive language through which to, well, express ourselves. Another words, it was a mind-bendingly stupid exercise in utmost ridiculousness – typical for a high school.
For example (and it’s the only example I’ve chosen to remember of this) we weren’t supposed to refer to a frog as croaking. No, we were supposed to feel as if we were frogs ourselves and feel how a frog would verbalize itself croaking. (Pretty high demands for a frog.) Since this exercise was so thoroughly ludicrous, and therefore impossible, the priest had to teach by example. So there he was, in front of the class, chanting out a verbalized frog croak which I have never ever, try as I might, been able to get of my goddam mind. So here it is:
Kai yi, karodak: Kai (rhymes with eye); yi (rhymes with why – an appropriate word); ka- (rhymes with duh -also an appropriate word) – ro (row) – dak (rhymes with slack).
Altogether now: Kai yi karodak!
Again: Kai yi karodak!
Now try to get that out of your minds for the rest of your lives. I warned you. I told everybody my comments would annoy them.
But you’re wondering, what, for chrissake, does this ever have to do with getting an ‘inferred’ global temperature? Think about it. That priest of our’s had Compo beat by at least 40 years. Kai yi karodak is an ‘inferred’ frog. Just how good a frog do you think that is? Do you think anybody, anywhere is going to mistake a bunch of repressed high school kids chanting Kai yi karodak for a lily pond full of frogs? So, just how good is an ‘inferred’ temperature?
All together: Kai yi karodak!
@Steven Mosher: “a small bias ( like less than .1C per decade ) isnt very interesting when it comes to understanding the future trajectory of temperatures.”
Are you referring to a linear regression through the two temperature sets? It appears to me that the reconstruction changes the shape of the line, not just its slope. And in fact seems to push back the start of The Lull to around 1995. That’s a bad thing for the idea that a linear increase is happening and all we can really debate is how steep is the slope.
Or am I misunderstanding which bias you’re referring to?
Rick Powell, “Correct me if I’m wrong, but there are error bars on that first graph. That’s what the light blue envelope is, right?”
Those are the error bars allowed by UEA/CRU and UKMet; a whopping (+/-)0.2 C in the 19th century, trending to (+/-)0.05 C by the late 1990s. Analyzing the historical methods, they’re about 10x too small.
Bloke down the pub says:
April 8, 2013 at 11:33 am
Was that paper co-written with Foggy and Clegg?
More like Nora Batty.
(P.S. I wonder how many of these good people know what we’re talking about?)
These people lost me when they said they ignored observations and just inferred from them. Can you say “garbage in-garbage out”?
What I would really like to see with all of these climate change horror stories is how the writers (and supporters) are changing their behavior to reduce their impact on the environment.
Do they rise/retire based on the available sunlight? Charge their various batteries using only locally-produced sun or wind power? Walk or use a bike for all of their transportation needs? Grow their own food instead of relying on the food chain that uses all those chemicals, trucks and so on to get the food from farm to market? Use the internet for meetings instead of jetting off to various locales for their climate change meetings? Have they really reduced their own carbon footprint or do they still use everything they want while telling us that we have to change?
Or as a pundit frequently states – “I’ll believe it’s a crisis when the people who tell me it’s a crisis start acting like it’s a crisis.”
Yikes, discard the inconvenient data, infer new data and then re-analyze the lot……..
People get paid for this ????
How about I infer the minimum takeoff speed for an airplane by counting the number of swizzle sticks in the galley…….
Cheers, Kevin
Dr Compo has, at a quick glance, smashed the bucket correction (see CA about Folland and Parker).. The fact that his is a land temp series is irrelevant because sea temp drives land temps. How do I know? Because there’s a ***peer reviewed*** paper which proves it:
A 2008 study – “Oceanic Influences on Recent Continental Warming”, by Compo, G.P., and P.D. Sardeshmukh, (Climate Diagnostics Center, Cooperative Institute for Research in Environmental Sciences, University of Colorado, and Physical Sciences Division, Earth System Research Laboratory, National Oceanic and Atmospheric Administration), Climate Dynamics, 2008)
[http://www.cdc.noaa.gov/people/gilbert.p.compo/CompoSardeshmukh2007a.pdf] states: “Evidence is presented that the recent worldwide land warming has occurred largely in response to a worldwide warming of the oceans rather than as a direct response to increasing greenhouse gases (GHGs) over land.
So the spike in temps during WWII is revived.
Dr Compo. are you now in a position to answer Prof. Wigley’s question? You know, ‘why the blip?’ There is an interesting paper from the FAO about fish productivity during WWII which is a GIF(?) file, and as such unfindable, which details windspeeds during the war: Cuff a passing postgrad and send it to the library. It will repay the search.
JF
Then Google “Kriegsmarine hypothesis”. Good luck. Can I come along to the ceremony when you get the big one?
Worried about an Ice Age? I can give you a cheap boost to global temps: half a degree C for about 100 billion blatts per year. Apply at above address.
I’m thinking this might be a first step to a face-saving walk-back on the part of (some of) the alarmists. The data reinforces that temperature has stabilized over the past 10 to 15 years and also suggests that the climb rate prior to that was lower than previously touted. It could be said “new analysis techniques show that it isn’t as bad as we thought”, without having to really admit that the earlier hoopla was based on faulty assunptions. Migtht be a way to allow the rat out of the corner.
I rather like this. I think it may be possible to reconstruct temperature trends using barometric pressures and oceanic ENSO conditions. My complaint: I wouldn’t use sea ice levels as that is clearly more driven by wind and ocean current than it is with air temperature.
@Green Genes 3:12 pm (and bloke down the pub 11:33am)
Not many! But those that do are still chuckling. I’d trust them above the warmist crowd: the Summer Wine boys did have their own internal logic that, in its way, worked.
Isn’t it inconvenient for those who claimed the following :
“In fact, many climate specialists now agree that actual observations from weather satellites show no global warming whatsoever–in direct contradiction to computer model results.”
Leipzig Declaration
“Instrumental temperature data for the pre-satellite era (1850-1980) have been so widely, systematically, and unidirectionally tampered with that it cannot be credibly asserted there has been any significant “global warming” in the 20th century.”
Surface Temperature Records : Policy-Driven Deception?
“What stands out for you in that graph?”
What I noticed first was that the wiggle matching stank until 1980 is reached. From there to 2010, the wiggles match fairly well. It looks like what they did was create a model, standardize it on recent CRUTEM4 data to make the right hand fit look good, then generate the left hand part. They may have additional knobs and levers in the model, just in case there’s a wild deviation somewhere that they want to tune out.
I think there’s less here than meets the eye. My feeling is that the use of proxies where none are needed* is an act of desperation. What’s next? Speleological temperature proxies based on bat poop accumulations?
iirc, others (Muller et al, etc.) have compared SST’s to global data sets and gotten fairly good correlation**. If so, there’s not much new here. It would be interesting to see how important to the Compo correlation were barometric pressure and arctic ice. It would be even more interesting to see what other input variables they tried, and how many.
* if you believe CRUTEM4 hasn’t been corrupted.
** not terribly surprising, since the oceans have 1100 X the heat capacity of the atmosphere at full depth, and the top 400 meters is still over 100 X.
Pamela Gray says: “I wouldn’t use sea ice levels as that is clearly more driven by wind and ocean current than it is with air temperature.
Doesn’t matter, if they needed something to tweak the correlation in a particular direction.
Julian Flood says: “Dr Compo has, at a quick glance, smashed the bucket correction (see CA about Folland and Parker).”
I’ve already plotted the Compo reanalysis versus the “raw” ICOADS data and will post it tomorrow.
What did I notice? every single cooling period has been removed, and become flat lined.
They’ve used the Land Temperature record to infer the LT relationship with the reanalysis inputs haven’t they?
A circular proof?
Reminds me of Trenberth’s missing heat. If they could help Trenberth find his heat; perhaps, they could understand why their temperatures don’t match actual recorded temperatures.