2,000 Years of “Rate of Temperature Change”

The word unprecedented is often used when warmists are discussing the rate that the Earth’s temperature is rising.  Oddly enough they have never once shown a chart that showed the rate of change.  They show the recent increase in temperature or they show a hockey stick of the past 1,000 years.  The end result is always about the same, a chart that shows the Earth has never before behaved in this manner.

As usual, that claim is incorrect.  Many Skeptic websites like to discuss the Medieval Warming Period (MWP) as proof that the current warming is not unprecedented, but once again that has nothing to do with the rate of temperature change.  The Earth could be cooler than the MWP and still have a rate that was unprecedented.  A rate that was significantly higher than usual would indicate that something was going on with the Earth’s climate that was new.  That would certainly give some weight to the argument that global warming was real and was happening.

One of the most comprehensive peer-reviewed temperature reconstructions I have found was that by Anders Moberg in 2005.  It uses multiple proxies to reconstruct the temperature of the past 2,000 years.  This also happens to be a paper that is frequently used by both sides to debate the MWP.  Here is the overall reconstruction by Moberg.

The Inconvenient Skeptic

Moberg, 2005 Temperature Reconstruction based on multiple proxies.

This is where things get interesting.  My method was to determine the rate of temperature change for 50 year periods from 25 – 1954.  In this manner I would determine if the historical rate of the Earth’s temperature changes.  Comparing modern rates to historical rates would then show if modern rates are statistically different from historical rates.  This was also done by performing same regression for the Blended set that I most commonly use.  In this way I can compare the rate of change up to the present that includes the most recent 2010 temperature data.

The results show that the modern warming is not the fastest rate of warming that has taken place in the past 2,000 years.  The award for that goes to the period the 44 year period from 542-586 that had a peak warming rate for a 50 year period of 0.0114 °C/yr.

The Inconenient Skeptic

(Blue) Moberg 50 year rate of warming, (Red) Instrumental 50 year rate of warming, (Dark Red) Max rate of warming.

Even though there is an alignment difference between the instrumental and the reconstruction, the 50 year rates of warming are very well matched.  The Moberg peak rate in 19001-1902 of 0.0091 °C/yr is comparable to the instrumental peak rate of 0.0094 °C/yr in 1928.  It is also worth noting that the peaks in 1928 and 1985 are also matched in the instrumental record.  Neither one of them matches the peak rate of warming in the past 2,000 years.

I also show the same data, but for only the past 1,000 years so the resolution is better.

The Inconvenient Skeptic

(Blue) Moberg 50 year rate of warming, (Red) Instrumental 50 year rate of warming, (Dark Red) Maximum Rate of warming. Rates are for the past 1,000 years.

Several items stick out to me.

Ten times in the past 1,000 years the rate of warming has been significant for at least a 50 year period.

The most extended period of warming was during the 1700’s when warming happened for almost the entire 100 year period.

Since 1600, the rate of cooling has never been below -0.005 °C/yr.  In effect, the strong cooling took place prior to 1600 AD.

The strongest cooling was in 1440 when the 50 yr rate was -0.0141 °C/yr.

So in the past 400 years the rates of cooling been lower than average, but such periods have happened before. The net result is that the modern warm temperatures have been 400 years in the making, not 40 years.  Absolutely nothing in the past 100 years is abnormal in the rate of temperature change.

This result shows that the temperature of the Earth is always going through a cycle of warming and cooling.  Both the warm periods and the cool periods are constrained and show no signs of being unbounded.  The 20 year peak rate of warming in the instrumental period happened in 1994 and the subsequent 6 years showed that the rate of warming has decreased.  In a few more years the decreasing rate of warming will be evident in the 50 year data.

There is no evidence in the Moberg reconstruction of the past 2,000 years that the current rate of warming is unusual in any way.  The rate of the recent warming is comparable to each of the warming peaks in the past 1,000 years and substantially less than the peak warming over the past 2,000 years.

Posted in Climate and Fear and Misinformation and Skeptic by inconvenientskeptic on April 4th, 2011 at 1:36 am.


This post has 10 comments

  1. Joris Vanderborght Apr 4th 2011

    Isn’t the problem with the alignment of the proxies based graph and the instrument record data a serious problem? What could explain this?

  2. inconvenientskeptic Apr 4th 2011


    While I admit it would be nice for proxy reconstructions and direct measurements to be well aligned, the simple fact is that they won’t align that well.

    Take the ice core data for example. The temperature of the ocean has an effect on the ice core data. Since nothing changes temperature as slowly as the ocean, there will be time lag between the proxy data and the temperature that would be measured at a site.

    Proxies are good for the scale of change (some better than others), but not for comparing exact dates to temperatures.

    Time mis-alignment in proxy data is expected to some degree.

  3. nofreewind Apr 4th 2011

    The rate of temperature change is really the crux of the matter. There has been some warming the past 130 years, the question is, is it unprecedented? Is the Hockey Stick chart correct? Of course not, it is ridiculous to accept that as true. All you have to do is read some historical records, like Brian Fagans book, (he “believes” by the way, so his books are safe if you are a warmer), and see that just about every page of historical records contradicts the theory of a stable climate. Unless of course, you just take the stand that all of that was regional. But to think “climate change” is a new phenomena, and we are seeing examples all around us with “changing weather” is so ridiculous and sad to see the stupidity that is now running rampant in our culture, and of course this is all being taught and taken as science. When most of it is sheer nonsense.

  4. Murray Apr 15th 2011

    What data do you use for the recent instrumental record? It is almost certain that the CRU trend is biased to warm by at least some degree, and NASA GISS is certainly biased. There is a lot of evidence that the recent warm peak (1998-2006?) is no warmer than the prior peak (1938-1944?). If that is true how would your recent warming compare?

  5. inconvenientskeptic Apr 15th 2011


    The blended data incorporates the CRU, GHCN, UAH and RSS. I have articles that describe it in more detail as well.

  6. njyoder May 11th 2011

    You made the mistake of starting off with one methodology, then alterting it in your analysis to fit the data. You started off with rate of change, but then ended up with not-rate-of-change items in your analysis, as well as the sudden inclusion of the arbitrary description “significant” to describe past changes (this may or may not be–but it is not appropriate to do so lacking a scientific definition), when you started off concerned with the highest rates of change.

    A 100 year “extended period of warming” is irrelevant to your original thesis (after all, your thesis was about rate of change and you can have long periods of warming at very slow rates of change), and you are committing the same fallacy you sought to disprove by including it (anyone could have said the same without rate of change data). Also, as mentioned above and below, it’s bad to just include scientifically undefined english descriptions as being significant. You then suggest that a 400 year period having a lower rate of cooling is meaningful. That would be meaningful to the total amount of change, but not the rate of change. So there was, what, only ONE period where the rate of change was greater in the 2000 years (but not past 1000)? You can’t deviate from your initial methodology only after you see how your analysis pans out, it’s scientifically dishonest, and leads to endless cycles of similar behavior involving revised methodologies.

    There are also two main issues with the assumptions regarding the meaingfulness of pure rate-of-change data, anyway.

    Firstly, rate of change is not the only important measure here. It doesn’t even need to be “unusual” to be substantially harmful to humans, nor to be human-caused. Both of those can easily be true without it being an “unusual” rate of change. Although, your own results suggest this would be the second highest rate of change in 2,000 years, correct? That seems unusual.

    Secondly, I should point out a problem that often arises when you only consider rate of change alone. Some of the peaks are quite high, but relatively brief. There was nothing in this proposed methodology to measure this in a scientifically meaningful way.

    What is considered to be a high enough rate of change and in a long enough period to be considered substanstially unsafe to humans (in terms of predicting future trends)? I’m not sure. No simple metric tells you that. I don’t think there is enough that can be known just from this temperature data to determine that, which is why it’s pointless to conclude from this “oh, we must be safe now.” It certainly would be one of the worst hasty conclusions one could make.

    All of this is basically why it’s not a good idea to purport to disprove a huge number of scientists on a complex subject in a blog post. It’s also why this wouldn’t get published anywhere, even ignoring the strong intent to disprove from the onset.

  7. inconvenientskeptic May 11th 2011


    The purpose of comparing historical rates of change is to determine the very scientifically accepted fact of decadal and century period variability. Most scientists accept that variability as legitimate.

    I used the same methodology and got comparable results. The results are what the results are. I am a scientist with many years experience. Sorry you don’t like the results, but that does happen.

  8. njyoder May 14th 2011

    You didn’t actually address any of my points. Considering I offered a variety of points of critique, it’s rather disingenuous.You simply responded with a strawman suggesting that I thought the data was invalid or that such variability wasn’t real, when I clearly said nothing of the sort.

    The main issues in this discussion are whether the current trend is going to be substantially harmful to humans and what its causes are. Trying to argue against some other claims will just end up being a pointless strawman against the whole of those who believe it is human caused (i.e. a tangent that doesn’t get to the heart of the issue and only serves as pointless distraction/flamebait).

    In regard to those issues, the problem is with your methodology/analysis of said data. The validity of the data itself–the temperature and rate of temperature change graphs–aren’t in question. You could have chosen different ways to statistically analyze the data to produce rate of change graphs (to be used in addition to the existing graphs) and thusly, different ways to analyze those resulting graphs, but chose the most simplistic possible way. You drew a hasty conclusion based entirely on qualitative analysis which wouldn’t be acceptable even if the prior analysis was accepted on face value. Why? Because the questions are: A) is such a rate increase harmful to humans? and B) did humans significantly contribute to the current change? For A, we know of past periods in 2000 years that have been, so we can’t arbitrarily rule that out simply because other periods of great change exist. For B, The analysis does nothing at all to determine this, because obviously “this isn’t unusual” doesn’t mean “this isn’t human caused.”

    With such qualitative analysis, one could easy offer a variety of hasty conclusions, which is why peer-reviewed, scientific journals simply don’t accept that. They don’t accept a conclusion that completely lacks any quantitative criteria to determine what’s considered “significant” for the results (notice how I also included the time period and not just rate of change). Normal methodologies will, before even doing the analysis, determine what the different quantative values actually mean in comparison to each other. This would be good for a junior or sophmore statistics assignment, maybe, and pretty much represents what I’ve seen in that regard.

    For example, you said that over the past 400 years that the negative rate of change was below average, resulting a 400 year build up of temperature. Since we’re only dealing with conclusions drawn qualitatively, one could just say that this, by your own description, is unusual. This is why hard sciences avoid exclusively qualitative description based conclusions almost entirely.

    You never developed any sort of algorithm to quantify and determine the meanings, let alone an algorithm to accurately predict future temperatures (which is of key importance to questions A & B). Even if you had developed the former, you’d still be lacking the latter (even an approximate form of it), which is what is necessary to draw conclusions regarding A & B. A proper scientific paper would describe the potential implications of the results, both in support of and against your hypothesis (you completely lack any explanation of alternate meanings). I am not saying this to insult you, but rather to point out that the difference is very apparent to anyone who reads such journals for comparison.

    You also committed a fallacious appeal to authority. Appealing to yourself as an authority is generally a bad idea, especially when you aren’t an expert in the field at all. You’re a chemical engineer working on semiconductors. If you had at minimum of a graduate (preferably doctorate) degree in a directly relevant field and had publications in a relevant, peer-reviewed scientific journal, then you might be able to start calling yourself an expert. You have been working years as an engineer, not even a scientist. Such appeals to authority are out of place and it’s just plain strange that anyone would attempt to use one.

    I should note that, as I expected, you immediately assumed you knew what my stance on global warming is, simply based on me criticizing your article. It’s an unfortunately common phenomenon and one used to justify to oneself’s not bothering with a complete, logical analysis in rebuttal.

    BTW, I do find it concerning that your wife pressured you to “make a choice” regarding a stance on global warming. The default stance of science is to be agnostic (unknowing of the conclusion) and remains that way until complete, conclusive evidence is found. Deliberately seeking out to draw a conclusion, regardless of which one it is, is an unscientific strategy. The proper strategy is to study the evidence then, and only then, determine what can and can’t have conclusions drawn about it. You may end up drawing no major conclusions, which is antithetical to the mentality of “I’ve got to figure out which viewpoint to step behind.”

    Your blog, including its very own title, indicate that any reading or analysis you do in the future, will be approached with the intent of trying to use it to support a specific conclusion.

  9. inconvenientskeptic May 14th 2011


    It is fair enough to say that I didn’t spend enough time reading your previous comment before replying. I don’t always have as much time as I would like for such things.

    The purpose of this analysis was not to determine statistical validity of the data but to display natural variability in the rates of warming. The disparity in the two sources of data preclude a truly meaningful statistical result from such a comparison. What my analysis shows is that there are natural periods of warming and cooling that happen in a fairly regular and cyclical manner. This is a generally accepted fact, but not accepted by all. I could easily cherry pick papers that support one side of the argument and not the other (like so many other websites do), but I chose to look at the numbers myself in many ways.

    When I find something that I think it interesting, I put together one of these articles. I found it interesting that the historical rates of temperature change show the pattern that they do and that the magnitude of the warming historically is comparable to the modern rate of warming. Such broad behavior is usually more useful at understanding the behavior of a complex system than any specific statistical comparison.

    Just like more days are not at the average temperature, but the broad seasonal trends are useful in predicting the general behavior of the weather. That is more of what I am looking at. In the broad perspective, there is nothing unusual occurring. In practical terms statistics has a very difficult time predicting what will happen. I see this in my “real” job as a semiconductor engineer all the time where the goal is to keep everything the same all the time. Using statistical process control methods is very limited. People that understand system behavior are much better at detecting what is going on than the various statistical methods are.

    As for your other comments about peer-review and appealing to myself and an authority. I have spent enough time looking at enough data that I have a pretty good grasp on what the Earth’s climate is currently doing. I did not reach my conclusion lightly, but I have developed some very interesting things that have not been published and won’t be until the book is out. I am confident that the Earth is not going to warm up in any hazardous way in the future. That conclusion is what got me into the entire debate. It was only after I reached the conclusion that I decided to be an active participant in the debate.

    As for the comments about the agnostic aspects of science. That is an ideal that is rarely achieved. The reason that Jenny wanted me to make a choice was because she felt reducing CO2 emissions mattered and I didn’t really care one way or another. So I was agnostic on the whole topic of global warming. She wanted me to be more active as a participant. So I said I would study the topic on my own and reach my own conclusion and that is exactly what I did. I am also now fully active as a participant in the global warming debate. Just not in the way she expected, but she is used to being around me as I discuss how to balance the heat load in the house to optimize the air conditioning so the cost is lower and the temperature gradients are smaller.

    I made this website and titled it exactly so very intentionally after reaching some important conclusions. The biggest problem facing humanity today is the single perception that the Earth doesn’t change. Making plans and expecting the Earth to stay constant is perhaps the greatest mistake we as a species has ever made. The belief that the Earth has a proper and normal temperature is false. The oceans do not have a “correct” level and there is not a proper amount of Arctic Sea Ice. The idea that the Earth will stay the same if we reduce CO2 is false as is the idea that it should stay the same.

    If everyone accepted that single fact, then the discussion about how to deal with the future would have meaning. Currently the discussion is not based in that reality, but the false perception that the Earth would stay the same if only humanity wasn’t screwing it up. More than anything that is why I have become an ardent skeptic.

  10. Dyspeptic Curmudgeon Jun 10th 2011

    It would be interesting to see a rate-of-change analysis carried out on the temperature history over a much longer period…say 65 Million years! As the absolute changes in temp of that term are far greater than any during the last 2000.

    See here: http://joannenova.com.au/2010/02/the-big-picture-65-million-years-of-temperature-swings/

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