Friday, March 27, 2009

Global Warming Tiger - Data Bias

This is the second of the series Global Warming - Tale of the Tiger.

Read the Tale and a description of the figure to the left. I believe the apparent 0.8ºC increase in Global Temperature over the past 150 years is due to three major causes and one minor one, as indicated by the parts of the "tiger".


This posting is about DATA BIAS which I think is responsible for about 30% of the apparent warming. In other words, 0.2ºC to 0.3ºC of the apparent 0.8ºC temperature increase is not actual warming.

(However, the remaining 0.5ºC to 0.6ºC is actual warming, and needs to be addressed.)


The figure below is a "blink comparator" of the official NASA/NOAA GISS (Goddard Institute for Space Studies) USA temperature anomaly (from Credit for the graphs goes to

More about the above graph near the end of this posting!


NASA/NOAA specifies measurement sites in five classes, with the best at least 100 m (over 300 ft) from any source of artificial heating or land development and the worst located right on an occupied building. According to a 2009 survey, only about 3% of official sites in the US are at Class 1. About 8% are in Class 2, at least 30 m from a source of artificial heat. About 20% are in Class 3, between 10 and 30 m. The remaining stations are closer than 10 m to an artificial heat source (58%) or right on a heat source (11%).

Thus, only about 11% are in the best two classes, reasonably distant from artificial sources of heat, while 69% are in the worst two classes, easily affected by nearby heat sources. Over 2/3rds of the official reporting stations in the US are close enough to artificial heating sources to be affected. We have no idea if the situation is better for foreign stations, but it is likely even worse!

Of course, since Global Warming has to do with changes in temperature, if a station has been at the same location for decades, any change in reported temperature should be consistent with actual trends in that area, right?

WRONG! Stations in urban areas, even if they have been in the exact same place, have been affected by lifestyle changes, such as installation of air conditioning in buildings that had none fifty years ago, more auto and truck traffic, and construction of nearby buildings. But, many stations have been moved from time to time and thus have not been in the same place all this time, and most have been affected and encroached by civilization and changes in land use.

Why are the stations so close to artificial heat sources? Well, fifty or more years ago, all the readings were taken manually by volunteer observers twice a day. They were not about to walk the length of a football field to do so. Even as automatic reporting stations were introduced, the stations had to be close to buildings so the telephone and power wires could be run to them.


"One swallow doesn't make a spring." (Aristotle). Even two doesn't prove it is spring. Likewise, the following anecdotal evidence does not prove the case for measurement bias. However, human beings seem to be moved more by specific examples than by statistical evidence. So have a look at these two stations about 50 miles apart in north-central California with very different temperature plots.

Orland, CA has a well-located station that has been in the same place for 100 years. The period from 1880 to 1900 shows a precipitous dip in mean annual temperature of about 2ºC. Mean temperatures have been in the same approximate range since 1900, with a small dip in the 1940's.
Marysville, CA, around 50 miles away, has seen considerable encroachment by development. The shelter that houses the MMTS temperature sensor is close to air conditioning exhaust fans and you can see their effect in the 2ºC mean temperature rise from 1940 to the present.

Sadly, the second example is far more representative of reporting stations than the first.

How could two temperature measurement stations, only 50 miles apart, experience such large differences in annual mean temperature trends? The only explanation is measurement bias due to encroachment of development at the second station.


Indeed, NASA/NOAA has retroactively corrected the data to account for measurement error. Here is that "blink comparitor" again.

Remember, this is OFFICIAL published data from NASA/NOAA GISS in 1999 and then in 2008. They have adjusted the data by about 0.3ºC which is more than 30% of the apparent Global Warming over the past 150 years.

Since the data has been biased by proximity to artificial heating sources which tend to increase over time, you would expect them to adjust the data to show less actual warming in later years. However, they seem to have made the "correction" in the wrong direction!

Check the blinking graphs! For data before 1970, they have REDUCED the temperatures by up to 0.1ºC. For the years after 1970, they have INCREASED the temperatures by up to 0.2ºC. This retroactive "correction" has added 0.3ºC o the apparent warming.


I have only scratched the surface on reasons to suspect data bias. There are dozens of photos showing official temperature measurement sites that are clearly too close to artificial heat sources that have obviously encroached relatively recently. There is evidence that painting the sensor enclosures with modern, longer-lasting latex paint rather than the old method using whitewash has increased temperature readings in the warm part of the summer.

What if I suggested that all official sites in Class #4 and Class #5 should be abandoned and replaced by new sites that met the requirements of Class #1 (or at least Class #2)? Well, the Global Warming alarmists would be up in arms, and for good reason, because that would wipe out most of the apparent temperature increase.

I agree with them! Since much of the data from years ago came from stations that were in very close proximity to human development, the old data is biased towards higher readings.

On the other hand, I think everyone should agree that encroachment of measurement sites by human development, especially over the past 40 years as air conditioning and vehicular traffic became more common, has biased recent data towards higher readings.

I don't have the power to correct the measurement stations that have been encroached, nor do I have the base data to make exact corrections. However, I think it is clear that a substantial portion of the apparent Global Warming increase is definitiely due to data bias. I estimate this bias as about 30% (+ 0.2ºC to +0.3ºC). Does anybody agree or disagree with that estimate? On what basis?

(However, I hasten to repeat, the remaining 0.5ºC to 0.6ºC is actual warming, and needs to be addressed.)

Ira Glickstein


Howard Pattee said...


You said in a P.S. “I did not expect you, of all people, to show such respect for experts.”
You are right! Skepticism is the only safe strategy, and the “weight of experts” makes skepticism harder to support. You are also right to doubt the data, which is where skepticism should begin. You are convincing, but there much more worldwide from data than NASA/NOAA.

Coincidentally, today’s NYT Magazine has a cover story on Freeman Dyson, a man after your own heart. Here is an excerpt, but read the whole article.

Global warming, he added, “has become a party line.” What may trouble Dyson most about climate change are the experts. Experts are, he thinks, too often crippled by the conventional wisdom they create, leading to the belief that “they know it all.” The men he most admires tend to be what he calls “amateurs,” inventive spirits of uncredentialed brilliance.

Climate-change specialists often speak of global warming as a matter of moral conscience. Dyson says he thinks they sound presumptuous. As he warned that day four years ago at Boston University, the history of science is filled with those “who make confident predictions about the future and end up believing their predictions.”

Dyson found his muse in J. B. S. Haldane. “Haldane was even more of a heretic than I am,” he says. “He really loved to make people angry.” It wasn’t all science. On trips into London he spent entire days in bookstores where William Blake “got hold of me. What I really liked was he was a really rebellious spirit who always said the opposite of what everybody else believed.”

Haldane was also largely responsible for my switching from physics to biology. I got to know him the year before he died.


Ira Glickstein said...

Thanks, Howard, for the link to the NY Times Magazine article about Freeman Dyson, the eminent physicist and my fellow "Civil Heretic" when it comes to AGW - human-caused Global Warming.

It is sad that he has received personal insults and lost friends over his civil questioning of AGW (even though he is "an Obama-loving, Bush-loathing liberal" :^).

The story veers towards suggesting that Dyson, at age 85 "is far gone — out of his beautiful mind." [emphasis added] Of course, "A Beautiful Mind" is the title of the book and movie about John Nash, the Nobel 1994 Economics winner who suffered from schizophrenia. The next sentence quotes Oliver Sachs who wrote the famous The Man Who Mistook His Wife for a Hat book saying that Dyson's mind "is still so open and flexible". This suggests anyone who questions AGW orthodoxy is bonkers and his open mind may be due to a hole in his aging head.

The NY Times story does not explain Dyson's science-based issues with AGW at all. It makes it appear he is all about character assassination: "...climate change has become an 'obsession' — the primary article of faith for 'a worldwide secular religion' known as environmentalism. ... Dyson has been particularly dismissive of Al Gore, whom Dyson calls climate change’s 'chief propagandist,' and James Hansen, the head of the NASA Goddard Institute for Space Studies in New York and an adviser to Gore’s film, 'An Inconvenient Truth.' ... 'The biologists have essentially been pushed aside,' he continues. 'Al Gore’s just an opportunist. The person who is really responsible for this overestimate of global warming is Jim Hansen. He consistently exaggerates all the dangers.' "

The only science-related aspect of AGW I found in this very long article has to do with Dyson's theory that (1) increased CO2 in the atmosphere is not necessarily a bad thing, and (2) excess CO2 could be removed from the atmosphere, if desired, by planting a trillion genetically-engineered trees. IMHO both are reasonable, but are made to appear simple-minded. They do not capture Dyson's real science-based arguments against the idea that human burning of excessive quantities of previously sequestered carbon (coal, oil, natural gas) are the main cause of the Global Warming we have experienced nor are we in any danger of reaching a "tipping point" from the positive feedback of increasing carbon.

Ira Glickstein

PS: Thanks for writing "You are also right to doubt the data, which is where skepticism should begin. You are convincing, but there much more worldwide from data than NASA/NOAA." Global Warming, by definition, is a worldwide issue. If data bias is responsible for about 30% of the apparent US warming, and if most of the rest is due to natural cycles not under human control (as I will try to show in subsequent postings) that would apply worldwide, would it not?

Ira Glickstein said...

To add to Howard's posting here is a link to Freeman Dyson's own words about carbon and global warming (2007).

Near the end, Dyson admits to having given bad advice to the young Francis Crick - that he should stay in physics and not switch to biology. Crick, along with James Watson, later discovered the double-helix of DNA.

Interestingly, in Howard's earlier comment, he says J.B.S. Haldane "was largely responsible for my switching from physics to biology. I got to know him the year before he died." Haldane also affected Dyson. He says "Haldane was even more of a heretic than I am. He really loved to make people angry."

And, of course, Howard Pattee, as Chairman of my PhD Committee, changed my view of AI and taught me all I know about hierarchy theory and biological systems. He continues to enrich my life (and I hope others) here on our Blog. THANKS!

Ira Glickstein

Ira Glickstein said...

Since I made the original posting, additional survey owrk has been done and a Comprehensive Report with photo-documentation has been made available.

Based on this new report, I believe my estimate that about 30% of the apparent global warming is due to measurement bias is a low estimate. The true error is likely to be over 30% and perhaps 40% or more.

Please read the report linked above if you are interested.

Ira Glickstein

Ira Glickstein said...

Still more evidence in favor of my estimate that Data Bias is responsible for some 30% of the apparent 0.8ºC Global Warming over the past 150 years.

Comparing ground-based vs satellite data for global temperatures indicates bias in the ground based-data of about 0.2ºC. NASA GISS data indicates an increase of 0.21ºC from 1997-2008 while the two satellite-based data indicate 0.02ºC to 0.04ºC, a difference of nearly 0.2ºC, or 25% of the rise since 1997. Combine that with the 0.1ºC downward adjustment of the data prior to the 1970's and the total Data Bias is well over the 30% I estimated.

Ira Glickstein