Boulder Escapes Global Warming

Guest post by Sam I. Outcalt

Boulder USHCN climate monitoring station. Photo by Anthony Watts

Abstract: The historic record of the mean annual air temperature record at Boulder does not display the major “global” climate transitions detectable in the total annual precipitation record. Hurst ReScaling is demonstrated to be a powerful tool to examine climate change.

Background: The citizens of Boulder, Colorado are extremely active in efforts to combat, research, and attenuate the impact of “Global Warming”. It is therefore instructive to look at the temperature record of this city as a means of understating the high level of concern that has led to municipal and county carbon taxes and other mandates by the local green machine. The Modern Warming Regime began in 1976 with the “hockey stick” upturn in “global” temperature data. There is a large body of evidence indicating that the warming ended with the 20th Century. The footprint of that event on station thermal records is spatially irregular. Strong 1976 integral signals are found in the mean annual temperature (MAT) data of some stations in Colorado. These stations are concentrated in the Northwest quadrant of the state. Fort Collins is in the group but Boulder is not.

The Data: Let us begin with an analysis of the air temperature history. The temperature record at Boulder beginning in the late 19th Century extending just past the the end of the first decade of the 21st Century is presented as Figure 1.


Figure 1. The mean annual air temperature station record at Boulder, Colorado.

Several years ago Outcalt discovered that inflections in the integral traces of serial climate data indicated regime transitions. In Figure 1 air temperature history integral inflections in 1932, 1967 and 1986 break the record into five regimes. The Boulder station record is missing strong integral inflections that are present around 1936 and 1976 in “global” temperature records (see Figure 1 and Appendix GLOB).

The 1976 inflection became famous as the base of the “hockey stick”, which signaled a steep temperature rise in the “global” air temperature data. There is a steep regime warming trend between1986 and 2011 in the Boulder station air temperature record but it’s end may be signaled by the steep downturn in the 7 year moving average in 2004, near the record end. It is clear that while a large area of the globe suffered the impact of Global Warming, Boulder escaped ! Is the record at Boulder representative of a larger area ? As a check the averaged GHCN and HadCRUT3v grid air temperatures were examined in a 10×10 degree parch centered on Boulder. This pooled grid data is presented as figure 2.


Figure 2. The integral of the pooled gridded data for the period from 1940 to 2008 displays the well known 1976 transition and a transition in 1998 followed by a steep downward trend which has a much steeper cooling slope than the preceding warming trend.

The gridded regional data displayed integral defined weak warming trend from 1976 to 1998. This indicated that there was no pronounce warming during period of modern warming from 1976 to 1998.

To check if the regional and station records are synchronous they are they were plotted together for the short time span of the gridded data as Figure 3.


Figure 3. The records appear synchronous indicating that the long term station record must crudely reflect the climate transitions in a wider region.

Having established the synchronous character of the overlapping records the difference between the station and grid record is displayed as figure 4.


Figure 4. The range of deviations and clustering of deviations with the same sign may indicate the suppression of real regime transitions and the introduction of false positives.

The stark differences in regime trend slopes in the station and grid records at the end of the 20th Century may be an artifact of record length although other sources of this contrast are possible.

It should be noted that the Hurst ReScaling method used to detect climate regime transitions is also sensitive to station moves to new sites (Runnalls and Oke (2006)). This extreme sensitivity suggests that station site move and/or raw data adjustment may introduce false positive regime transitions and/or mask real regime transitions. The clusters of deviations of the same sign in Figure 4 suggest some distortion may have been introduced into one or both data sets.

As precipitation is not as sensitive air temperature to urban effects as air temperature an exploration of the long term Total Annual Precipitation [ TAP ] record might prove interesting as earlier investigations showed that the signature of both the 1936 and 1976 regime transitions in Arizona TAP data. TAP records are also not as visible in the climate debate as MAT records so they may be free of the semi infinite adjustments suffered by the MAT records. The Boulder TAP record from the same source as the MAT record is displayed as Figure 5.


Figure 5. The Boulder station TAP record and it’s integral trace. Note the 1936 and 1976 “global regime transitions” are visible as major inflections in the integral trace.

In Figure 5 that the major “global” regime transitions that occurred near 1936 and 1976 are prominent. This clearly illustrates the power of the rescaling technique in climate analysis.

Conclusion: This brief examination indicates that the effects of “global warming” were minimal at Boulder in the shorter gridded data set and insignificant in the context of the long term station record. In short the city that has a hyper active response to “Global Warming” never experienced it ! However, Boulder did experience the impact of the regime transition in its precipitation history. It is evident that the Hurst Rescaling technique is a robust but underutilized tool in the analysis of climate change and other serial data.


Outcalt,S.I.,Hinkel,K.M.,Meyer,E . and Brazel,A.J.(1997) The application of Hurst rescaling to serial geophysical data. Geographical Analysis 29, 72-87.

Runnalls,K.E. and Oke,T.R.(2006) A technique to detect micro-climatic inhomogeneities in historical records of screen-level air temperature. Journal of Climate 19: 959-978.

Appendix GLOB


Major inflections near 1936 and 1976 form a broad minimum on the integral traces of global temperature departures from the record mean from 1880-2008.

Hurst ReScaling, more info:


Sam Outcalt is a retired Professor of Physical Geography, University of Michigan, Ann Arbor

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February 19, 2013 4:22 pm

(1) Please clarify your use of the term “integral” as a transition point in the temperature record in the first few paragraphs, now, it is not clear.

Alan S. Blue
February 19, 2013 4:36 pm

Can this be extended to a -localized- subset of the satellite records?
(Yes, I know they aren’t measuring the same thing. But using a point-source instrument to estimate average gridcell temperature is inherently a ‘proxy’ relationship as well.)

February 19, 2013 4:46 pm

More on the Boulder carbon tax.
Boulder (Colorado) implemented the United States’ first tax on carbon emissions from electricity, on April 1, 2007, at a level of approximately $7 per ton of carbon. According to the City of Boulder, the tax is costing the average household about $1.33 per month, with households that use renewable energy receiving an offsetting discount. The city expected the tax to generate about $1 million annually until its expiration in 2012, with the revenues used to fund Boulder’s climate action plan to further reduce energy use and to comply with the Kyoto Protocol (Kelley 2006). In June 2009, the City Council voted unanimously to raise the tax level, effective Aug. 6, 2009. Although press reports did not specify the new rate, the expected increase in revenues, some $810,000 annually, suggests that the increase is on the order of 80%, or perhaps $5-$6 per ton of carbon (on top of the original $7/ton).

Louis Hooffstetter
February 19, 2013 4:47 pm

Sam, this is a good effort, but it’s tough to read. The points you are trying to make are not very clear.

John Andrews
February 19, 2013 4:48 pm

Sorry, gridded annual average information is not data!

February 19, 2013 4:56 pm

Is this local temperature vs global temperature?

February 19, 2013 4:58 pm

Sorry if I didn’t get the point 🙂

February 19, 2013 5:07 pm

The article does take a little study, but I thought it quite clear with a little study. The only question I could not quite figure out is the reasons for the inflections in ’36 and ’76 and I would appreciate it if someone would expand on this a bit.
I live close to Boulder and always appreciate it when someone takes them apart. A lot of intelligent people live there, but boy are they arrogantly dumb.

February 19, 2013 5:15 pm

I think I got it Now! very clever.

Mark S
February 19, 2013 5:17 pm

The citizens of Boulder ,Colorado are extremely active in efforts to combat, research and attenuate the impact of “Global Warming”.
Is the second comma supposed to be there?
[Fixed. Thank you. Mod]

Richard Keen
February 19, 2013 5:22 pm

Sam, you should be aware that the supposed station data for Boulder in your graph has already been adjusted. The source may call it raw data, but it’s not – it’s been homogenized.
If you want the actual observed annual means, go to the Western Regional Climate Center:
Note that there’s some missing data in that collection that’s not really missing in reality.
Or go to the Climate Diagnostics Center site:
That data was collected by Cathy Smith on her own initiative, and it includes some observations made by me and a few others to fill in holes in the co-op record.
Note, for example, that 1954 has a 56.02F, or 13.3C, annual mean temperature. I have the printed data from those years that verify that this is the actual observed reading. Your graphed data from CDIAC gives 11.5C, adjusted downward by 1.8C!!!
The reason for the adjustment is the sordid history of the Boulder station, which from 1947-1970 was on the asphalt roof of the downtown fire station. I did a cross-check between Boulder and Denver, and that fire station exposure introduced a +2F (+1C) bias to the annual means.
Then there was a period 1978 into the 1980’s when the thermometer was surrounded on three sides by brick walls, and the rain gauge was within shooting distance of a lawn sprinkler. Curious, but some days Boulder had the only precipitation in the state.
Since 1990 the records are good; the guys who do the observations are real pros and true weather geeks.
I taught a weather data class at the U of C for a dozen years, and would give the history of the Boulder station as a living example of how NOT to do long-term records, and of all the caveats one should use when using such data.
But then I’d take the students on a field trip to the station – the one in the picture – and the observer would give them a good lesson on how TO make weather observations.
BTW, I’m also a co-op observer, at a site in the high hills SW of Boulder.

February 19, 2013 5:24 pm

I have thought for many years what an excellent opportunity the global warming/climate change/catastrophic whatever movement represents to the psychological profession. It is not all that often when a new religion is born. Correct me if I am wrong, but I think the last time this occurred was when Mormonism sprang forth, some half a century before Freud was awarded his PhD, and even longer before he began the science of psychotherapy.
But this new religion has sprung forth right before our very eyes, and is anyone studying it from that perspective? Somewhere between the late 1970’s to the early 1990’s this new belief structure sprang forth. At least by the first IPCC assessment report was in gear. It was 1996 before we discovered the major oceanic oscillations nowadays referred to as AMDO/PDO. So the discovery of “global warming” more or less corresponds with the last known flip between the negative and positive modes of what is now shown to be an average 60 year oscillation cycle, the warm mode of which forms the basis of this new belief system.
Sam provides an even more poignant perspective: “In short the city that has a hyper active response to “Global Warming” never experienced it!” Confirmation of both a scientific falsification and a belief structure unhinged from the scientific method.
Perhaps it is just a limited perspective on my part, but it is hard not to see this as anything other than the birth of yet another pagan belief structure.

Richard Keen
February 19, 2013 5:26 pm

Leg says:
A lot of intelligent people live there, but boy are they arrogantly dumb.
>>> I departed Boulder for the hills 30 years ago, and that’s one reason why. I left the Boulder Reds to become a mountain Redneck, so to speak. And I’m south of the 40th parallel now (Baseline Road), and can speak freely (like an escaped North Korean).

February 19, 2013 5:27 pm

Typographical errors, unclear use of language, and a meaningless conclusion. This site usually maintains a higher standard. I’m disappointed. Can we go back to the Russian meteor?

H.R. (off fishing in Florida)
February 19, 2013 5:39 pm

Yeah, but… just think how hot it would have been if they hadn’t instituted “carbon” taxes. They really dodged a bullet there, eh?
(do I really need /sarc?)

February 19, 2013 6:26 pm

Your post is quite interesting. For me it was especially interesting because we observed some common to Boulder data features in sea surface temperatures of tropics and north middle latitudes. You can see a draft of manuscript at
Your article (Outcalt,S.I.,Hinkel,K.M.,Meyer,E . and Brazel,A.J.(1997) The application of Hurst rescaling to serial geophysical data. Geographical Analysis 29, 72-87) is also interesting. Do you think that this method is suitable for the verification of our hypothesis?

February 19, 2013 6:54 pm

I see (from the comments) that Boulder started their CAGW-fearing tax, then found out the that tax wasn’t raising enough money for the liberal politicians to keep rewarding their supporters with contracts and money – but who DID find that it wasn’t raising many protests either ! – and so …. The liberal politicians raised their carbon tax.
Note that the carbon tax did NOTHING to lower CAGW anywhere in the world, but it DID raise local revenues that could be used “prophet-ably” BY the local politicians on their friends, but who wanted to raise the taxes ONTO others who were not their friends.

February 19, 2013 7:46 pm

“…As precipitation is not as sensitive air temperature to urban effects as air temperature…” should be “As precipitation is not as sensitive to urban effects as air temperature…” I think.

February 19, 2013 8:50 pm

I have the mixed experience of living for 40+ years in the “People’s Republic of Boulder”, surrounded by the likes of Trenberth, Solomon, the intellect-challenged Serrezze, Caspar (The Ghost of the Jesus paper) Amman, and I was for a while the next-door neighbor of Steve (Dr. Stephen, to his “colleagues”) Schneider. He was a jerk in the 80s – – RIP
Boulder is blessed with remarkable, inspiring landscape and commodious climate, but cursed with an excess of liberal intellectualism, marginal Marxist-Communist ideology, and a firm majority Democrat demographic that insures some of the dumbest public-policy initiatives get cast into municipal code, taxation, regulation, and citizen-participation boards and commissions. Group-think is too kind a description.
R. Keen is right that Boulder’s temp/precip record is just as compromised as many other USHCN stations in the country. A lousy basis for expensive public policy decisions.
W. McClenney is spot-on with his observations of the congruence between climate-calamity belief and other religious fervors. Boulder is the Holy See of Modern-Man Self-Flagellation, replete with sin taxes and regulations for plastic bags, styrofoam, prairie dog reverence, “sustainability”, and the whole lot.
RACookPE1978 correctly diagnoses the political dynamic here. A “carbon tax” did nothing but provide a revenue stream for municipal propaganda and “awareness training activities”, which quickly became insufficient to support the expanding bureaucracy of bean-counters, propagandists, enviro-consultants, and other hangers-on. So, of course, the city asks for more tax revenue which the Starbucks/Whole Foods/spandex/Pilates/eco-brain-dead will reliably approve as tithes to Gaia.
A rational, scientific mind can only observe and sigh – logic and facts hold little sway here.

February 19, 2013 9:00 pm

Boulder has it right, the carbon tax works! Just like the climate models work –retroactively!

Philip Bradley
February 19, 2013 9:29 pm

The area behind the fence is an irrigated cemetery. It seems every second surface station I look into is in proximity to irrigation, which IMO makes temperature measurements worthless as changes in irrigation can produce temperature changes substantially larger than the claimed AGW warming.
Here is a news report from 2007 that states the cemetery will change its irrigation schedule.

February 19, 2013 10:45 pm

I have looked at some data from Cheyenne at 41.15 degrees latitude which is very near to Boulder.
My results suggest that it was warming there from 1973 at a rate of ca. 0.02 degrees K per annum until around 2000. So that would be ca. 0.5 degrees up from 1973 until 2000, assuming the equipment was 100% correctly calibrated. If I read the first graph in this post, the seven year running average was around 9.8 or 9.7 in 1973 and around 10.3 in 2000. So there is reasonable correlation between what we both measured there (ignoring the ups and down in between).
My results on Cheyenne further suggest that since 2000, temperature has gone down at a rate of ca. -0.08 degrees K per annum, on average. That is almost 1 degree K down from 2000-2012.
You do see this happening in Boulder as well, but you better look at figure 3. The results in figure 3 suggest an average of around +0.5 in 2000 falling to -0.2 by 2007, a difference of -0.7.
So, knowing the results for Cheyenne, I know that Boulder will also have fallen further down in the past 5 years. So, the statement that Boulder “escaped” warming is surely not correct. It is cooling there, as it is in Cheyenne. And the current observed rate of cooling there is about 1 degree K per decade.
Also, my data set also suggests that this global cooling will last until at least 2038.
So, if I were a farmer there, I would think a bit about those results before making my decisions on what to sow.

February 19, 2013 11:28 pm

I’ve spent 4 weeks in Boulder – probably way more than the average U.S. commenter here. 😉 There was no global warming and, as far as I remember, no discussions about global warming in Boulder back in 1999 – but the concept was undefined to start with and we didn’t know what to expect. The Rocky Mountains etc. were beautiful.

wayne Job
February 20, 2013 1:39 am

One can only commiserate with those that live in this area that understand the truth, their thoughts and wishes will be drowned in propaganda.

February 20, 2013 3:53 am

Seems to be an exception to the Colo trend.
In trying to debunk some alarmist claims, I looked at the NCDC temp records for the divisions of Colo. By those graphs, Colo is one of the FEW areas that are strongly and steadily WARMING over the last century. Warming shows about equally in all the NCDC divisions of Colo, but the trend seems to be especially focused on the west face of the Rockies in Colo, Wyo, and NM. It fades when you go north into Montana, and it’s entirely gone in the western section of Kansas.
Presumably the NCDC divisions aren’t fine-grained enough to show county-sized movements.

February 20, 2013 4:35 am

So, on what are the carbon taxes that Boulder & the county are collecting being spent?
(And why does pasting of comments into the reply block no longer work – risking a tremedous increase in misspellings? 🙂 )

February 20, 2013 4:50 am

When I last visited Boulder, while driving around in my friend’s Prius, he wasnt talking much about the weather in Boulder, but more the weather in the front range, where it seems that the minimum temps are not as low as they were 30 years ago. He suggested that the milder winters at the Estes Park level and higher has resulted in the beetle infestation (which has really wrecked RMNP) and the mosquitoes now found at high elevations (which means we now need repellent while backpacking). Documentation of the higher mountain temps can be found in Plos1, “Elevation-Dependent Temperature Trends in the Rocky Mountain Front Range: Changes over a 56- and 20-Year Record” McGuire, Nufio, Bowers, and Guralnick, and the paper is not behind a pay wall.

Michael A.
February 20, 2013 5:09 am

Is it a coincidence that the last graph looks like a fourth-order polynomial or is that an artifact of the calculations obvious to the non-math-impaired?

February 20, 2013 6:13 am

Boulder is a nice place, made a dozen or so trips there in 2005-2006, stayed at the Boulderado. Even got a chance to drive up into the Mountains one trip.
But they are a kookie bunch, the prairie dog laws is I think a good look into their particular form of insanity.

February 20, 2013 6:39 am

Carbon Tax and Boulder – is this spent within CAGW? Wondering, better LED light bulbs, cleaner electric taxis, bicycle/ice-board lanes? In Kalifornis the budgetary process is the auto-washer Spin cycle. Creative Financing (first heard in early 70’s government coffee breakroom) allows all revenue to go into the drum at full spin speed. When the effluent is seemingly drained, hands go into the spinning drum and withdraw the ready to use damp clothing. Interstate Highway Fund came along later in the spin cycle.
Irrigated space around the Stevenson Screen house? Humidity and local wind-upslope downslope cross-slope? Has this ever been studied (not the BEST kind)? There are places in the Sacramento Valley West aspect-Sierra foothill-valley contact points where the rice fields in full grow have a feel like ’66 Long Bean (ha ha) rice paddies. By moving around to the SE popcorn dry wind flow.
Colorado is the example of big government concentrated cities. A few cities control the mass geographical area. Like Sparta of old. Unless mother nature pushes cold wet snow-3 ft August nights for half a decade, nothing natural will change – carbon tax will be a pot on the stove. The EU thrives on U.S.A. handouts including commerce-security (we recently gave France millions to fight their war) if all this was cut 100percent perhaps the business of Carbon tax would dry up.

February 20, 2013 9:33 am

Polistra says
Seems to be an exception to the Colo trend.
I looked at the NCDC temp records for the divisions of Colo. By those graphs, Colo is one of the FEW areas that are strongly and steadily WARMING over the last century.
Henry says
I just told you that I looked at the records of the airport in Cheyenne 41.15. According to those records it cooled by about 1 degree K there from 2000-2012.
We see the same trend in the first graph of Boulder – look at the 7 year running average from 2000? Do you see it falls from 10.5 to 10? Unfortunately the graph runs only until 2007, but I bet you will find a further drop of 0.5 from 2007-2012.
Records from before 1930 cannot be relied upon unless you can bring me the relevant calibration certificate? Just one is enough.
– they did not know in those days that thermometers need to be re-calibrated regularly….after manufacture.

February 20, 2013 1:48 pm

Earlier this afternoon, the photo of the Boulder weather station was clear and undistorted.
Now, skewed: as if the image were no longer scanning digitally.

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