Saturday, December 22, 2012

Dr. Hoo issues a challenge. Oops.

Climate-scientist wannabe Hoo issues a challenge:

Dr. Egnor,

I have asked you several times to state whether you agree with Judith Curry's assessment:

"Has there been any warming since 1997 (Jonathan Leake’s question)? There has been slight warming during the past 15 years."

Do you agree with it?


Let's take a look at the link for Curry's statement.

The date of Curry's post quoted by Hoo is February 7, 2012.

During the week of October 6-13, 2012, the Met Office (a climate science center) released updated data. Journalist David Rose of the U.K. Daily Mail pointed out that the data showed no significant warming:

Dana Nuticelli, a warmist climate scientist, took issue with the Daily Mail's report on the data in an article on October 13, 2012.

On October 16, 2012, Dr. Curry, in reply to Nuticelli's article, posted:

[Judith Curry's] note to defenders of the idea that the planet has been warming for the past 16 years 
"Raise the level of your game. Nothing in the Met Office's statement or in Nuticelli's argument effectively refutes Rose's argument that there has been no increase in the global average surface temperature for the past 16 years. 
Use this as an opportunity to communicate honestly with the public about what we know and what we don't know about climate change. Take a lesson from these other scientists that acknowledge the 'pause', mentioned in my previous post Candid comments from global warming scientists"

In addition, Dr. Curry responds to the argument that a "statistical analysis" of the data shows warming:

"how does this refute [the no-warming] argument? No statistically significant positive trend, and it makes it look like SkS [the warmist website that put up the calculator] hasn’t done their homework with the latest data."

So Hoo quoted Curry's February 7, 2012 post about earlier data, which is not the data we are discussing.

Curry's viewpoint on the data we are discussing (in the graph above) is stated in my quote from her dated October 16, 2012.

Dr. Curry agrees that the graph above shows "no statistically significant positive trend".

Hoo can't get dates right. He was referring to Curry's earlier opinion about a different data set.

Or perhaps Hoo, statistical maven, knew exactly what he was doing, and he was hoping you wouldn't notice.


  1. Dr. Egnor,

    Permit me to quote Dr. Curry at some length, rather than provide a juicy sound byte (as you like to do). The excerpt is from Dr. Curry's post Sunday Mail... again dated October 21, 2012. In other words, it is more recent than your quote mine. Here is what she wrote, inter alia:

    The ‘facts’, such as they exist, are the data; in this case the latest release of HADCRUT4. This is new data, so people haven’t yet had much time to analyze and interpret it. However these data end up being analyzed, the trend since 1997 is very small, much smaller than the decadal trend of 0.2C that we have been led to expect by the IPCC for the early part of the 21st century. The whole issue of cherry picking start and end dates is a red herring, as I’ve argued in my previous post Trends, change points and hypotheses. It depends on what hypothesis you are trying to test. If you are using data to evaluate the IPCC’s projection of 0.2C/decade warming in the first two decades of the 21st century, with plateaus or pauses at most of 15-17 yrs duration, well then you can pick whatever start date you want. It will be very interesting to see what Press Complaints Commission comes up with regarding Rose’s article.

    The highlighted sentence neatly summarizes Dr. Curry's views as I presented them earlier:
    * There had been a warming trend of 0.1 degree per decade in the 20th century.
    * We expected a larger trend of 0.2 degrees per century in the 21st.
    * We got a warming trend in the last 15 years, but it is small; smaller than the expected 0.2 degree per decade.

    The link in that quote goes back to the February 2012 post in which Dr. Curry states that "there has been slight warming during the past 15 years."

    So yes, Dr. Curry affirms a slight warming trend in the last 15 years. She did it in February of 2012. She did it again in October 2012.

    Do you agree with her on that?


  2. It also helps to know how Judith Curry defines a pause. You will see that she puts the word in scare quotes in the October 16 post:

    Take a lesson from these other scientists that acknowledge the 'pause', mentioned in my previous post Candid comments from global warming scientists"

    Why the scare quotes? It is a good bet that the writer meant to caution the reader not to accept the word at face value. That perhaps it is a carefully defined term and the reader should be aware of that.

    So how does Judith Curry define a `pause' in the global warming? And does she? Oh yes, she does. In her 2011 post Pause (?):

    Further, addressing these questions requires an unambiguous definition of ‘warming’, ‘stopped’, and ‘paused’. ’Warming’ means a rate of change of temperature that is greater than zero. Here I define “stopped” to mean a rate of change of temperature that is less than or equal to zero. Here I define “pause” to mean a rate of increase of temperature that is less than 0.17 – 0.2 C/decade.

    It is in this sense that Dr. Curry uses the word `pause' when she puts it in scare quotes. She does not mean to say that there is no warming trend. She means to say that the warming trend is small. Had she meant to say that there is no warming trend then she would use the word stop, not pause.


    1. @Hoo:

      Curry: "No statistically significant positive trend"

      You are making yourself look like an ideologue who will twist the data any way you can think of the buttress your argument.

      That's a fair assessment, I think.

      Now, you seem to be evading an explanation for the pause, especially in light of the major increase in CO2 over that same period.

      Why not focus on the important questions, such as why there is a pause that is a long as the warming was, despite major increases in CO2.

    2. Dr. Egnor,

      This is another attempt to use quote mining to make a point. It looks like you are interested in sound bytes, not in understanding the issues.

      Let us see the quote in a proper context and understand what exactly it signifies. In her post Judith Curry (JC) was responding to Dana Nuccitelli (DN):

      DN: The Skeptical Science temperature trend calculator can be used to test this question. The trend in the HadCRUT4 global surface temperature dataset since 1997 is 0.084 ± 0.152°C per decade (although we have not yet updated the HadCRUT4 data, the GISS and NCDC datasts show a similar warming trend since 1997). While the trend is not statistically significant, the central value is positive, meaning the average surface temperature has most likely warmed over this period.

      JC comment: how does this refute Rose’s argument? No statistically significant positive trend, and it makes it look like SkS hasn’t done their homework with the latest data.

      In this exchange Dr. Curry does not make her own assessment of global warming in recent years. She merely restates Dr. Nuccitelli's assessment that the 1997–2012 warming trend "is not statistically significant." What does this expression mean? Does it mean that the data show no discernible warming? No, it does not. Let us take a closer look.

      Dr. Nuccitelli says that the positive trend between 1997 and 2012, 0.084 ± 0.152°C per decade, is not statistically significant at the 2σ level (the uncertainty she quotes is 2 standard deviations). She does say, however, that the average is positive, so the data more likely reflect a warming trend than a cooling one. Dr. Curry does not disagree with that. In fact, she has said many times (as I showed with her quotes) that there is a warming trend.

      So what is the statistical significance of the data mentioned? Clearing the 2σ threshold would mean that the trend is positive with 98-percent confidence; there would be a 2-percent chance that the trend is negative but random fluctuations make it look positive. We cannot say that about that specific interval. In this case, the mean is smaller than 2σ but is greater than 1σ. The trend is positive with a 84-percent probability and negative with a 16-percent probability.

      What happens when we look at the 16-year interval from 1996 to 2012? The numbers are 1996–2012: +0.107±0.131 °C/decade (2σ uncertainty). The trend is +1.6σ, meaning that the odds that it is a fluke, and the actual trend is negative, are down to 5.5 percent. We are 95-percent confident that the world has warmed since 1996.

      We can do that for other years as well. Here is a little table I compiled:

      1995–2012: +0.109±0.119 °C/decade, 96 percent confidence
      1996–2012: +0.107±0.131 °C/decade, 95 percent confidence
      1997–2012: +0.058±0.136 °C/decade, 61 percent confidence
      1998–2012: +0.052±0.153 °C/decade, 80 percent confidence
      1999–2012: +0.095±0.162 °C/decade, 88 percent confidence
      2000–2012: +0.056±0.179 °C/decade, 73 percent confidence

      So what do the data show? We are quite confident that the world has warmed since 1996. The years 1997 and 1998 were extra warm thanks to the strongest El Niño of the century. The resulting bump in temperatures exaggerates the warming trend for intervals where 1997 is the end point and masks the trend if 1997 is the starting point. All sane scientists agree on that point. Including Judith Curry.


    3. Temps have to be either warming or cooling, at least slightly. All other factors being equal, it's 50/50. Heads or tails.

      The "warming" trend is insignificant:

      Curry: "No statistically significant positive trend".

      It is the significance, not the warming, that counts. If there was very small statistically insignificant cooling, you would be saying "but it's INSIGNIFICANT!"

      Stop milking an obviously flat graph to buttress your ideology.

      Now answer my question as to why warming has been insignificant despite 16 years of massive CO2 emissions-- fully 1/3 of the total put into the atmosphere by humans.

      And point me to the model/warmist that predicted the pause.

    4. Dr. Egnor,

      What you write here indicates that you have no understanding of statistics. This time I was not surprised at your lack of knowledge, having seen you redefine a trend as a statistically insignificant change.

      When a statistical analysis yields a mean that is below 2 standard deviations, we do not declare that the outcome is 50-50. That would be silly. Here are some simple examples.

      If the analysis yields a mean of 0 and a standard deviation of σ then it is truly a draw: the measured quantity could have been positive or negative; random errors would push it to 0 with equal probabilities.

      If the analysis yields a mean equal to +1 standard deviation then it is more likely that the measured quantity is positive. How much more likely? Look at this graph. The area to the right of 1σ is 16 percent; the area to the left is 84 percent. So this analysis tells us that the measured quantity has an 84-percent chance of being positive and a 16-percent chance of being negative. It is 84-to-16, not 50-50.

      When the mean is +2 standard deviations, the chance of the measured quantity being negative and pushed to +2σ by random noise is (look at the graph) 2.2 percent. So in this case the odds are 98-to-2.

      You can declare statistical significance at various levels. Doctors are often content to declare statistical significance at a 95-percent level, whereas particle physicists insist on a 3σ confidence. It is an arbitrary line that you can draw at various places.

      So what are the data telling us? As you do not understand it yet, let me explain. I will again use my little table, this time showing the probabilities of both a warming trend and of a cooling one, based on the mean value of the trend and on its standard deviation.

      1995–2012: +0.109±0.119 °C/decade, warming 96 percent, cooling 4 percent.
      1996–2012: +0.107±0.131 °C/decade, warming 95 percent, cooling 5 percent.
      1997–2012: +0.058±0.136 °C/decade, warming 61 percent, cooling 39 percent.
      1998–2012: +0.052±0.153 °C/decade, warming 80 percent, cooling 20 percent.
      1999–2012: +0.095±0.162 °C/decade, warming 88 percent, cooling 12 percent.
      2000–2012: +0.056±0.179 °C/decade, warming 73 percent, cooling 27 percent.

      It is not 50-50. Even the cherry-picked 1997–2012 period is more consistent with a warming trend than with a cooling one.

      Now, what you call an "obviously flat graph" is an illusion. You are looking at noisy data and your eyes cannot make out a small positive trend in the noise. If you conclude on that basis that there is no trend then you are a fool. I showed in a previous thread that the temperatures in 1997 were lower on average than they were in 2012. What was your response? You just dismissed it without a shred of argumentation. What does that tell us? It shows that you are unable to work with data and are incapable of making a coherent argument.

      I suggest that you take some remedial classes at Stony Brook.


    5. Hoo:

      I've been doing science for a long time. I'm not a statistician-- I hire people for that. But I am quite acquainted with the methods and issues.

      I look at a lot of data sets in my research. I would never publish the above data as showing a significant increase in temperature. I don't do statistical manipulation.

      I try to look at the larger picture, and I only make evidentiary claims about things that are statistically significant and that demonstrate clear evidence for or against a hypothesis.

      I'm dealing now with data that looks a lot like that temperature graph. I would like the data to show a significant result, to support my hypothesis (the the Q factor of a windkessel notch increases with increasing intracranial pressure, if you want the details), but I will not make that claim in the paper about a graph like that above that yields insignificant results and does not show such results on inspection.

      I'm a conservative scientist, and I make claims I can defend without hand-waving.

      You have done quite a service here, Hoo: you've shown a fine example of the dodgy science at the core of global warming. Tons of statistical hand-waving and obfuscation employed in service to ideology.

      As Dr. Curry said:

      "Raise the level of your game. Nothing in the Met Office's statement or in Nuticelli's argument effectively refutes Rose's argument that there has been no increase in the global average surface temperature for the past 16 years.
      Use this as an opportunity to communicate honestly with the public about what we know and what we don't know about climate change. Take a lesson from these other scientists that acknowledge the 'pause',"

      Try some honest science, a bit of self-scrutiny and humility. Maybe your AGW hypothesis is wrong. This pause, occurring over an interval during which there has been a very large increase in atmospheric CO2, should give you pause.

    6. Dr. Egnor,

      It is very graceful of you to acknowledge that you are not a statistician. Neither am I, for that matter. The difference is that one of us understands enough statistics not to dismiss global warming, whereas the other does not and he dismisses global warming anyway. One of us also dos not understand that natural variations can somewhat mask the anthropogenic warming.

      Ironically, you write that you do not do hand-waving. Well, you have done nothing but. In contrast, I presented a simple statistical analysis demonstrating in at least two ways that 2012 was warmer than 1997. You did not even try to crunch the numbers. You merely dismissed all of that with a sleight of hand. Bare assertions, complete lack of understanding the terms, silly redefinitions, that is all you brought to bear in this discussion. Oh, and quote mines.

      In the end, truth will win. The warming trend of the 20th century is there for everyone to see. It is well beyond 2 standard deviations. Dismissing it as a fluke is a dishonest tactic that no longer works. When your children grow up, they will be loathe to admit that their father is a silly crank who rails against science. That is too bad.


    7. I'm a graceful guy.

      Very few modern scientists are statisticians. Statistics is a full-time job. We have a whole department that does it for us. It is the job of scientists to keep the statistics grounded, to make sure that GIGO isn't driving the results, to make sure that the results are considered in context.

      It is the job of scientists to look at the broader picture, and keep it honest.

      I don't doubt that the 20th century warmed, except for 1940-1980 and 1996-2000. We are emerging from the Little Ice Age that ended at the beginning of the 19th century, so natural warming is acknowledged by all.

      I question your assertion that the warming is man-made, and not natural, and I question your assertion that it is dangerous, and I question your assertion that it is continuing in any significant way. I question the data itself-- the siting and constant changes in temp measuring stations is very problematic, as are the manipulations of data that are routinely done to "correct" the problem.

      I seriously question the integrity of the AGW scientific community. I think their science is substandard and that many of them are gangsters in labcoats. I refer you to the Climategate emails for confirmation.

      Tell me: Your models didn't predict the Pause, so why should we trust them when they predict the apocalypse?

    8. Dr. Egnor,

      We can certainly discuss the 'pause' as it is defined by Dr. Curry, but first you have to acknowledge that you understand the definition as given by her.

      I would also like you to acknowledge that the data for 1996 to 2012 do show signs of a warming. At 95-percent confidence level as my numbers show above. The warming signal for that period is quite clear. You can plot the data yourself if you can or use the unfairly maligned calculator to do it for you.

      What do you say to this? I promise to get to the pause later.


    9. The data shows no significant warming. Insignificant warming, if present, is... insignificant.

      I accept Curry's analysis, not yours.

      Explain why we should trust models that predict apocalypse, that didn't predict the Pause.

    10. Dr. Egnor,

      You are confusing two periods. The warming is small, about 1 standard deviation, for 1997–2012. It is more substantial for any other starting year aside from 1997, which was bumped up by a strong El Nino.

      If you take 1996-2012, the warming trend is much more noticeable: 2 standard deviations, which means it is "significant" in the sense you are using. Go ahead and graph it. Don't be afraid. You only have your chains to lose.


  3. Michael,

    We know you're ignorant about science, climate science in particular (you've prided yourself for being so in the past). But if you start your period with a warm el Niño and finish it with a cool la Nina and limit it to just 16 years, then any change in average global temperature is obviously going to be statistically insignificant. It's the equivalent of taking a rigged coin, which will give 'heads' 75% of the time, tossing it twice and getting one 'head' and one 'tail' and declaring the coin 'fair'.

    No one claims that greenhouse gases are the only determinant of average global temperatures. AGW isn't based on graphs of average global temperatures over time (pretty though they are). It's based on the well known and well understood physical properties of greenhouse gases in absorbing and trapping heat in the form of infrared radiation, which has been known since the 19th century.

    Without greenhouse gases, the average global temperature would be -18 degrees Celcius.

    The Earth is still warming. And it's warming in the places models are predicting - in the Antarctic and in particular the high Arctic. The high Arctic is of particular concern because of the positive feedbacks. A Summer ice free Arctic Ocean means a decreased albedo, as more incoming solar radiation penetrates and warms the Arctic Ocean and less is reflected back into space. Thawing of the Arctic tundra means bacterial decomposition of the buried previously frozen vegetable material and release of the stored carbon as methane, an even more potent greenhouse gas than CO2.

    1. Global warming means global warming. If natural fluctuations can impede it, natural fluctuations can cause it.

      The warming period (1980-1996) that gave rise to apocalyptic hysteria is of the same duration as the pause (1996-2012). Just as the pause started at a warm el Nino and is now at a cool la Nina, the warming period started with an emergence from cooling for 1940 to 1980 and ended with a warm el Nino.

      Sauce for goose, sauce...

      Why is one period the harbinger of the end of the world, and the next-- well it doesn't mean anything!

      Junk science.

    2. Michael,

      OK. Let's look at global temperatures from 1940 to 2012. It's a nice long period. It includes several warming periods and several pauses. It even includes a cooling at the beginning, so it should understate any subsequent warming. It includes the period in which carbon emissions in the form of CO2 from the burning of fossil fuels and land clearing have gone from 1 million tonnes per day to 9.

      The trend is 0.090 +/- 0.017 degrees C/decade. Statistically significant. It doesn't matter whether you smooth the curve using a 12 month moving average, or introduce a lot of noise by using 1 month, as Rose does. It's exactly the same figures.

      There are other factors affecting global temperature besides greenhouse gases. Sometimes they add. Sometimes they subtract. But, over time, they're neutral. Which is the reason why you have to take a sufficiently long period.

      You keep on proving that you're ignorant.

    3. Dr. Egnor,

      It is wrong to say that the warming period is only from 1980 to 1996. The global temperature anomaly has been rising in the first half of the 20th century as well. There was a period when the temperature anomaly briefly went down and stayed flat, but most of the time it has been going up. Today we are a degree higher than we were at the beginning of the previous century.


    4. Why are you merely arguing that we are warming for the past century?

      We are emerging from the Little Ice Age. Of course we are warming (that's what "emerging from an Ice Age" means).

      The issue is: what is your evidence that it is man-made warming?

      Correlation with rising CO2? But CO2 has risen considerably since 1996, without significant warming.

      The Pause has occurred during a period of major CO2 increase. Did your models predict this? Why should we trust them to predict a warming apocalypse, if they didn't predict the Pause we are in now?

    5. Dr Egnor,

      Before we start arguing over theoretical aspects of the warming, we have to first agree on what the data show. Do you agree with me that the global surface temperature anomaly has increased by one degree Celsius since the late 1800s?


    6. Michael,

      The Little Ice Age is generally agreed to have finished in 1850. The cooler than average climate returned to the 'normal' temperatures in 1850. How long are you going to blame the Little Ice Age for the current global warming? 200 years? 500 years? A thousand?

      There are reasons for the Little Ice Age. The Maunder Minimum. The Black Death in 1347, causing human mortality of 30-50% across wide areas of Europe and Asia, and recurring every 15 years or so for at least 3 centuries. The introduction of Old World diseases such as smallpox, malaria, yellow fever and measles into the New World after 1492 more than decimating the native populations. The last two events causing reduced agriculture and regrowth of forests, soaking up CO2 and increasing cooling. Volcanic eruptions, including Tambora in 1815, which resulted in the Year without a Summer in 1816.

      Tha models can't predict a pause in global warming, because there's no way of predicting whether the solar cycle will be quiet (the current situation) resulting in less solar output and cooling. Or when a El Niño or La Niña event will occur. Or any volcanic eruptions will occur (although, apparently the eruption of volcano Unpronouncable in Iceland in 2010 wasn't large enough to cause significant cooling).

      We might be 'lucky'. We might go into another Maunder Minimum. We might have a global pandemic killing off 30-50% of the global human population. The supervolcano under Yellowstone might erupt (it's overdue). But it's not the sort of luck I'd want.

      The fact remains. We understand how greenhouse gases work to cause global warming. The physical properties of greenhouse gases is the basis of AGW, not pretty temperature graphs over time. Carping on the recent pause in global warming when it's an artifact of deliberately choosing the end points, and also because there are other factors playing a role is just lazy. There's a well understood mechanism making concern about AGW completely reasonable, in comparison to the Mayan calendar end of the world hoax.

    7. @Hoo:

      [Before we start arguing over theoretical aspects of the warming...]

      Answer my question:

      What models predicted the Pause? (cite them).
      If no models predicted the Pause, why should we trust the predictions of apocalypse?

    8. Michael,

      I've explained to you why the models can't predict a pause in global warming, because there's no model of the Sun that allows us to predict the strength of each solar cycle. There's no model of ocean currents that allows us to predict the timing of El Niño and La Niña events. There's no model of volcanic activity that allows to predict the timing and magnitude of volcanic eruptions.

      Scientists can't predict over short periods, but they can predict over decades, 30 years or so, because short term influences average out. My previous analogy still applies; you're like the man who tosses a coin, rigged to give 'heads' 75% of the time, twice, and gets one 'head' and one 'tail' and then claims that the coin is perfectly fair.

    9. "Scientists can't predict over short periods, but they can predict over decades, 30 years or so"

      "Scientists" predicted AGW in 1980.

      Thirty years is now, bach.

      Why have your models failed? Why should we trust them about the AGW apocalypse?

    10. Michael,

      OK. The global warming trend from 1980 to 2012 is:

      0.158 +/- 0.051 degrees C/decade.

      Again statistically significant. And also a higher increase in average global temperature than for 1940 to 2012. Even though a greater proportion is due to the recent 'pause'.

      The models haven't 'failed'. They just can't predict short term temporary factors such as solar activity and El Niño/la Nina events.

  4. Dr. Egnor,

    I do not understand your refusal to even acknowledge the facts and the desire to jump to theory. As I have written before, I am very much interested in discussing the 'pause' . But I think that we should first agree on the facts. One of the facts that seem incontrovertible is that the surface temperature anomaly has risen by one degree centigrade since the late 1800s. Do you affirm that?


    1. Your reluctance to discuss the failure of warming during the recent 16 years of massive CO2 increases is understandable.


      What models predicted the Pause? (cite them).

      How do you explain the pause, in light of the large rise in CO2, if human CO2 is driving warming?

      If no models predicted the Pause, why should we trust the predictions of apocalypse?

    2. Michael,

      I keep on explaining to you that no model can predict confounding factors such as solar output. And if you start with a warm El Niño and end with a cool La Niña, you're going to eliminate most of the warming due to cherry-picking your data.

      If you take the period 1990 to 2012, and avoid starting with an El Niño, the trend is:

      0.171 +/- 0.09 degrees C/decade. Not quite statistically significant but close. It could be close to 0. Equally unlikely, it could be 0.28 degrees C/decade. If I was a bettor (I'm not) I'd bet strongly on there being warming over this period.

    3. Dr. Egnor,

      I am flabbergasted by your flat refusal to affirm a simple fact and move on. As I have said many times, I will be happy to discuss theories. However, I see no point in discussing them with a person who is irrational to the degree that he denies the reality of the 20th-century warming.

      It is your choice, Dr. Egnor.


    4. Question:

      What global warming models predicted the Pause? (cite them).

      How do you explain the pause, in light of the large rise in CO2, if human CO2 is driving warming?

      If no models predicted the Pause, why should we trust the predictions of apocalypse?

    5. Dr. Egnor,

      You should say at least whether you will answer my question or not. I think you will not, but I may be mistaken.

      If you answer the question, I promise to address the pause.


    6. Oops,

      Actually the trend 1990 to 2012 is statistically significant.

    7. Dr. Bachfiend,

      Indeed it is. You quote the GISTEMP set, which gives a trend of +0.171±0.090 °C/decade at the 2σ level. The mean is +3.8σ.

      For HadCRUT4, the numbers are similar: +0.154±0.085 °C/decade at the 2σ level, with a mean of +3.6σ.

      But I am afraid Dr. Egnor is scared of looking at data. He might be data-phobic.
      That is a serious condition.


    8. @Hoo:


      What global warming models predicted the Pause? (cite them).

      How do you explain the pause, in light of the large rise in CO2, if human CO2 is driving warming?

      If no models predicted the Pause, why should we trust the predictions of apocalypse?

    9. Dr. Egnor,

      Are you planning to affirm the reality of the global warming in the 20th century? For if not the I see no point in discussing the finer aspects of a phenomenon with someone who denies its existence in the first place.


    10. The earth cools and warms, naturally. I accept the evidence for net warming in the 20th century, although I believe that the reliability of instrumental measurements is grossly overstated. Measuring sites change, the human environment of each site changes (urban heat island) and the "adjustments" for all of this are dodgy.

      All in all, I have no quarrel that there has been a small amount of warming in the 20th century.

      Now answer my questions.

    11. Thank you, Dr. Egnor.

      May I inquire how small? One degree centigrade?

      If you think the instrumental recor is unreliable, what reasons do you have to question its reliability? Here is Judith Curry in her post Pause (?). She thinks it is quite reliable:

      IMO, the significance of the BEST data in terms of the temperature record of the past 50 years or so is that it puts to rest the concern that Phil Jones and Jim Hansen have “cooked” the land surface temperature data. This has not been a serious concern among the people paying close attention to this issue and who actually read the journal publications and look at the actual data; but it is a concern in certain circles, and in the U.S. this concern has been raised by at least one Republican presidential candidate. The relatively small discrepancies between the BEST and the GISS and CRU data sets are of some interest; the apparent discrepancy with GISS has been resolved. Note: the CRU data set shows less warming than BEST over the past 15 years.

      A separate question, which I have previously asked and you have not responded to. What is your definition of the `pause?' Is it the same definition as Dr. Curry gives? You can find it in the same post:

      Further, addressing these questions requires an unambiguous definition of ‘warming’, ‘stopped’, and ‘paused’. ’Warming’ means a rate of change of temperature that is greater than zero. Here I define “stopped” to mean a rate of change of temperature that is less than or equal to zero. Here I define “pause” to mean a rate of increase of temperature that is less than 0.17 – 0.2 C/decade.

      Please answer these questions. You have plenty of time to do so as I am about to start driving to a vacation destination and will not have access to the internet until the evening. You can also start a new thread specifically dedicated to the `pause.'


    12. What global warming models predicted the Pause? (cite them).

      And here we have the core of understanding Egnorance. Egnor the full-time liar doesn't actually understand the science he talks about, he only understands slogans. If you ask him actual science questions, he can only respond with slogans, because that's all he knows.

  5. Michael,

    Simple questions:

    1. What are the natural drivers of global warming or cooling?

    2. If greenhouse gases cause warming from -18 degrees C to 15 degrees C (and this is simple physics, not doubted by AGW denialists - I'll go into the physics if you want...), then why shouldn't humans adding 30% to atmospheric CO2 levels since preindustrial times not cause further warming?

    3. If you doubt average global temperature graphs from the 20th century as being unreliable, why do you accept the one from 1997 to 2012 uncritically?