Forensic Science; Why Michael Mann Chose Only the Past 1000 Years to Reconstruct


Reading a post over on WUWT the other day I was shocked to learn the Michael Mann is still promoting his widely discredited “Hockey Stick” chart. (Click Here)

Speaker Summaries:
Dr. Michael Mann, at ease and confident at the podium, led off the evening by stating his hope for “a robust conversation” on how to address climate change. His presentation was based around the idea that the only debate to be had is on what to do about man-made climate change. Indeed, he stated this position several times, reinforcing it by clarifying that there’s no worthy debate to be had on whether there’s a problem, or that man has caused it. As a justification for this, Dr. Mann explained that the science behind anthropogenic climate change is verifiable fact. Incontrovertible. Well known and agreed upon for over a hundred years.

Of all the claims made throughout the evening, this is the one I found to be the most personally problematic. Clearly scientists such as Curry and Moore aren’t, to borrow a tired phrase, “denying” the basic science of atmospheric and radiative physics. To claim otherwise, or even to imply through omission, that they do so is unfair, untrue, and frankly, does nothing to increase the credibility of the presenter.

At any rate, moving on, as anyone familiar with this subject could guess, Dr. Mann’s presentation centered on his “iconic” hockey stick graph, noting that this year marks the 20th anniversary of its publication. The point he made sure to emphasize with the hockey stick was the “warming spike” of the late 20th century is unnatural, and unprecedented in tens of thousands of years. He noted that 2014, 2015, and 2016 were each record-breaking years for global temperatures, and cited his 2017 paper which ostensibly demonstrated there was only a 1 in 3000 chance that three consecutive years of global warming would be due to natural causes. In the course of his presentation, Dr. Mann made two specific claims: temperatures were now likely to rise by 4 to 5 degrees Celsius and sea levels by 6 to 8 feet.

If the best the climate alarmists can do is reference the greatest piece of scientific garbage ever produced, then they don’t have any case at all. The “Hockey Stick” should have been used by Dr. Curry and Dr. Moore as there evidence that the only evidence the climate alarmists have to support their case is pure garbage.

We’ve Addressed the Construction of the “Hockey Stick” various times on this Blog. (Search this Blog for “Hockey Stick” and or “Michael Mann”). Here are just two examples.

Multiple Sources Now Confirm; Climate Data “Adjustments” are Obvious Fraud to Anyone Choosing to Look

“We Only Have Thermometer Data for the Past Century”…Michael Mann

Michael Mann’s “Hockey Stick” chart has created some of the greatest scientific questions of our time:

  1. Why did the Hockey Stick not use available instrumental data prior to 1902?
  2. What about the physics and level of CO2 would justify a “Dog-Leg” in the chart precisely when the construction methodology changes?
  3. Is the “Hockey Stick” and “Mike’s Nature Trick…to Hide the Decline” independently reproducible?
  4. Why don’t other temperature reconstructions confirm/validate the “Hockey Stick?”
  5. Why, when Tree Ring, Coral and Ice Core Data go back thousands and even millions of years, did Michael Mann stop at just 1000 years ago, and limit it to the Northern Hemisphere?
  6. Why haven’t sea levels accelerated with the warming over the past 116 years?

This post will hypothesize why Michael Mann would cherry pick that timeline. By selecting the past 1000 years, Michael Mann was able to draw attention away from the fact that current temperatures are well below the level that existed during most of the Holocene. Over the past 15,000 years, there have been multiple warming and cooling periods, and the variability of temperatures have been much higher than today. Warming periods like the Minoan, Roman, Medieval and current warming all corresponded with the growth of civilization and past optimums all had temperatures higher than today. Coolings periods corresponded with societal collapse and violent revolutions. (Click Here)


By selecting the past 1000 years, Michael Mann conveniently chose a time period that began at a temperature optimum, The Medieval Warming, and covered the recent temperature minimum, The Little Ice Age. By choosing that select time period, he was able to manufacture the myth of steady temperature decline between 1,000 AD and 1902 (When his construction methodology changes) that was reversed by anthropogenic CO2, resulting in a sharp rise in temperatures post-1902. The following graphic highlights how ideal the time period selected is for making the case of a climate alarmist. Note how temperatures peak exactly at 1000.


From the above chart, it is evident that temperatures ofter rebound quickly after temperature minimums. The temperature minimums recorded 8,000 years ago was followed by a rapid increase of 4°C, 7,000 years ago followed by a rapid increase of 3°C, 5,500 years ago followed by a rapid increase of 2°C, so the current 1.5°C increase recorded in the “Hockey Stick” falls at the low end of the historic ranges. Additionally, the current temperature increase occurred during a period with much higher CO2 levels, yet temperatures remain well below previous Holocene temperatures peaks even if we accept the “Hockey Stick” as being accurate. Record high CO2 for the Holocene has not resulted in record high temperatures for the Holocene.

Note: The current CO2 level is over 400 ppm. (Click Here)


Another problem with the “Hockey Stick” is that it isn’t confirmed by long-term instrumental data. Multiple long-term instrumental records simply don’t show the sharp reversal starting in 1902. (Click Here) The following instrumental record for Central England goes back to 1650, and current summer temperatures are lower then they were in 1660, recent annual temperatures were below the level reached in 1685 and 1730, and recent winter temperatures were in line with temperatures back in 1730.


Controlling for the Urban Heat Island Effect, the case even gets worse. (Click Here)


Additionally, if in fact there was a sharp reversal in temperatures over the past 116 years, there would almost certainly be a trend change and acceleration in sea level increase. There isn’t. Here is the tidal gauge of Battery Park at the south end of Manhatten. Just recently the pre-El Niño low sent in 2016 was below the level reached in 1930 and 1935. The trend actually seems to be decelerating post-1970.


More importantly, if you maintain a consistent data set for the analysis, and not pick and choose proxies that give you the answer you want, things get even worse. Michael Mann had the luxury of picking and choosing what proxies to include in his reconstruction and deliberately avoided more accurate instrumental data. Tree rings are notoriously variable and impacted by local climate conditions other than temperature, such as precipitation, drought, and disease. Michael could pick and choose different tree rings depending on if he wanted to make the case for warming or cooling. (Click Here)

To address this issue, we will simply extend the Greenland Temperature chart featured above with actual instrumental Greenland Temperatures. (Click Here)

Over the past 130 years, temperatures in Greenland have shown a slight upward trend. Seen in a shorter time perspective, and apart from the warm decades of the 1930’s and 1940’s, temperatures have been decreasing. This trend is primarily observed on the west coast that not until recent years started showing an increasing trend.

Many of the Greenland Temperature charts are currently near RECORD LOWS!!! Many current temperatures are below the level reached in 1880. If you extend the above Greenland Ice Core chart with this data, the extreme warming Michael Mann manufactured in the “Hockey Stick” vanishes. Same would happen if you use temperatures from Antarctica or most likely any temperature data set not corrupted by the Urban Heat Island Effect. Michael Mann’s 20th Century warming is simply a manufactured illusion, exploiting the Urban Heat Island Effect and falsely attributing its effect to CO2. 100% pure sophistry, 0% sound science.


Facts are, Michael Mann can only make alarmist claims about temperature if he is allowed to rely upon his Hockey Stick Propaganda Poster. Real world data and most importantly highly accurate long-term instrumental data don’t support his garbage graph. Zoom back beyond 1000 years, and his alarmism completely collapses. There is no evidence, including the garbage Hockeystick, demonstrating that current temperatures are above the Minoan, Roman and earlier Holocene temperature optimums.  To make that claim they would need to go back and “adjust” all the ice core data.

Even if they did, they would still have to erase the archeological records of ancient tree lines, farming settlements in Greenland, vineyards in Northern England, ocean sentiment records in Denmark, etc etc etc. There are simply too many data sets and books that would need to be “adjusted” to manufacture the myth of current temperatures being an anomaly for the Holocene.

Unfortunately, Michael Mann has succeeded in controlling the conversation and has diverted attention from the real threat the globe faces…a coming ice age. Ice core records reveal a 100,000 yr/15,000 yr recurring cycle of glacial and interglacial periods. Catastrophic CO2 driven warming in 100% pure speculation and has never occurred in the past 700 million years, even when CO2 was as high as 7,000 ppm. A coming ice age is a near certainty. An emphasis on Wind and Solar Farms will result in widespread social unrest, starvation, and war. By then, however, Michael Mann and his ilk will be long gone, and future generations will have to suffer for their misguided political campaign.

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Unfortunately, the Climate Sophistry practiced by Michael Mann is difficult to combat. Casual observers simply don’t expect people with Ph.Ds to be so completely and utterly dishonest, so they give Michael Mann as much credibility as the other Ph.Ds that he may be debating. Debating people like Michael Mann is exceedingly difficult because they have no qualms about simply making stuff up, which is a debating tactic that really puts the opposition at a tremendous disadvantage. If people don’t have the scientific background to differentiate between a lie and the truth, the lie will often win, especially if the lie is what people want to hear.

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Many people on the left simply what to believe what he says, much like they want to believe President Trump colluded with the Russians and the FBI didn’t show any political bias (Click Here). They have no incentive to be critical of his work, and Michael Mann knows his audience all too well and fully exploits their willing complicity.

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The important point, however, is that a small cabal of science sophists have manufactured a climate crisis, and it has the potential to misallocate trillions of public dollars. We as a society have to decide if we are going to build roads, bridges, mass transit, hospitals, schools and parks, or are we going to piss that money away on Wind and Solar farms. (Click Here) (Click Here)

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11 thoughts on “Forensic Science; Why Michael Mann Chose Only the Past 1000 Years to Reconstruct”

  1. Brilliant snd courageous! Brave is the person willing to speak truth against the conventional wisdom.
    The collective lot of so-called scientists supported by the propagandists of the Democrat Party, educators and media would make Jodeph Goebels proud.


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