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Recent global warming trends: significant or paused or what?

As the World Meteorological Organisation WMO has just announced that “The year 2014 is on track to be the warmest, or one of the warmest years on record”, it is timely to have a look at recent global temperature changes.

I’m going to use Kevin Cowtan’s nice interactive temperature plotting and trend calculation tool to provide some illustrations. I will be using the HadCRUT4 hybrid data, which have the most sophisticated method to fill data gaps in the Arctic with the help of satellites, but the same basic points can be illustrated with other data just as well.

Let’s start by looking at the full record, which starts in 1979 since the satellites come online there (and it’s not long after global warming really took off).

trend1Fig. 1. Global temperature 1979 to present – monthly values (crosses), 12-months running mean (red line) and linear trend line with uncertainty (blue)

You clearly see a linear warming trend of 0.175 °C per decade, with confidence intervals of ±0.047 °C per decade. That’s global warming – a measured fact.

But you might have heard claims like “there’s been no warming since 1998”, so let us have a look at temperatures starting in 1998 (the year sticking out most above the trend line in the previous graph).

trend2Fig. 2. Global temperature 1998 to present.

You see a warming trend (blue line) of 0.116 °C per decade, so the claim that there has been no warming is wrong. But is the warming significant? The confidence intervals on the trend (± 0.137) suggest not – they seem to suggest that the temperature trend might have been as much as +0.25 °C, or zero, or even slightly negative. So are we not sure whether there even was a warming trend?

That conclusion would be wrong – it would simply be a misunderstanding of the meaning of the confidence intervals. They are not confidence intervals on whether a warming has taken place – it certainly has. These confidence intervals have nothing to do with measurement uncertainties, which are far smaller.

Rather, these confidence intervals refer to the confidence with which you can reject the null hypothesis that the observed warming trend is just due to random variability (where all the variance beyond the linear trend is treated as random variability). So the confidence intervals (and claims of statistical significance) do not tell us whether a real warming has taken place, rather they tell us whether the warming that has taken place is outside of what might have happened by chance.

Even if there was no slowdown whatsoever, a recent warming trend may not be statistically significant. Look at this example:


Fig 3. Global temperature 1999 to 2010.

Over this interval 1999-2010 the warming trend is actually larger than the long-term trend of 0.175 °C per decade. Yet it is not statistically significant. But this has nothing to do with the trend being small, it simply is to do with the confidence interval being large, which is entirely due to the shortness of the time period considered. Over a short interval, random variability can create large temporary trends. (If today is 5 °C warmer than yesterday, than this is clearly, unequivocably warmer! But it is not “statistically significant” in the sense that it couldn’t just be natural variability – i.e. weather.)

The lesson of course is to use a sufficiently long time interval, as in Fig. 1, if you want to find out something about the signal of climate change rather than about short-term “noise”. All climatologists know this and the IPCC has said so very clearly. “Climate skeptics”, on the other hand, love to pull short bits out of noisy data to claim that they somehow speak against global warming – see my 2009 Guardian article Climate sceptics confuse the public by focusing on short-term fluctuations on Björn Lomborg’s misleading claims about sea level.

But the question the media love to debate is not: can we find a warming trend since 1998 which is outside what might be explained by natural variability? The question being debated is: is the warming since 1998 significantly less than the long-term warming trend? Significant again in the sense that the difference might not just be due to chance, to random variability? And the answer is clear: the 0.116 since 1998 is not significantly different from those 0.175 °C per decade since 1979 in this sense. Just look at the confidence intervals. This difference is well within the range expected from the short-term variability found in that time series. (Of course climatologists are also interested in understanding the physical mechanisms behind this short-term variability in global temperature, and a number of studies, including one by Grant Foster and myself, has shown that it is mostly related to El Niño / Southern Oscillation.) There simply has been no statistically significant slowdown, let alone a “pause”.

There is another more elegant way to show this, and it is called change point analysis (Fig. 4). This analysis was performed for Realclimate by Niamh Cahill of the School of Mathematical Sciences, University College Dublin.

Fig. 4. Global temperature (annual values, GISTEMP data 1880-2014) together with piecewise linear trend lines from an objective change point analysis. (Note that the value for 2014 will change slightly as it is based on Jan-Oct data only.) Graph by Niamh Cahill.

It is the proper statistical technique for subdividing a time series into sections with different linear trends. Rather than hand-picking some intervals to look at, like I did above, this algorithm objectively looks for times in the data where the trend changes in a significant way. It will scan through the data and try out every combination of years to check whether you can improve the fit with the data by putting change points there. The optimal solution found for the global temperature data is 3 change points, approximately in the years 1912, 1940 and 1970. There is no way you can get the model to produce 4 change points, even if you ask it to – the solution does not converge then, says Cahill. There simply is no further significant change in global warming trend, not in 1998 nor anywhere else.

In summary: that the warming since 1998 “is not significant” is completely irrelevant. This warming is real (in all global surface temperature data sets), and it is factually wrong to claim there has been no warming since 1998. There has been further warming despite the extreme cherry pick of 1998.

What is relevant, in contrast, is that the warming since 1998 is not significantly less than the long-term warming. So while there has been a slowdown, this slowdown is not significant in the sense that it is not outside of what you expect from time to time due to year-to-year natural variability, which is always present in this time series.

Given the warm temperature of 2014, we already see the meme emerge in the media that “the warming pause is over”. That is doubly wrong – there never was a significant pause to start with, and of course a single year couldn’t tell us whether there has been a change in trend.

Just look at Figure 1 or Figure 4 – since the 1970s we simply are in an ongoing global warming trend which is superimposed by short-term natural variability.

Weblink: Statistician Tamino shows that in none of the global temperature data sets (neither for the surface nor the satellite MSU data) has there recently been as statistically significant slowdown in warming trend. In other words: the variation seen in short-term trends is all within what one expects due to short-term natural variability. Discussing short-term trends is simply discussing the short-term “noise” in the climate system, and teaches us nothing about the “signal” of global warming.

195 Responses to “Recent global warming trends: significant or paused or what?”

  1. 101
    Steve Fish says:

    DF and Kevin McKinney, this is a free pdf of the article. change/Data sources/Temperaure correction.pdf


  2. 102
    rd50 says:

    To # 89
    I think I was following the original post and others posting comments and suggestions looking/discussing the most recent temperature data, say from around 1998 or so vs year. Is the trend positive, negative or zero?
    So what is the best way to perform such analysis?

    An extremely difficult and probably impossible “best” answer for two reasons (or two difficulties).
    When you look at the plotted data, the increase (if any) is so very small.
    When you look at the plotted data, the variation (no question it is there, not if any) is so very huge. Another possible difficulty is always how many data points do you have in your correlation analysis, but here this is eliminated, we have enough.

    In the face of the two noted extreme difficulties, we may then say, OK, instead of trying to find the perfect solution to temperature vs years, let us try to find what is the temperature vs CO2 increase. Maybe it is easier to establish such and after all, what is the purpose of reducing CO2 release if there is no demonstrable relationship between the two.

    For some reason you do not want to look at the temperature data vs CO2 data for the years starting from 1958 when reliable CO2 became available. There is no harm in producing such a plot since we have extremely reliable CO2 concentration data since 1958. Then plot any and all of the available temperature data with such. This would be indeed quite interesting.

    Look at it this way. You need NO statistical analysis for the CO2 data. You have a pair of eyes and a brain. Linear increase in CO2 concentration from 1958 to now is obvious. Now, ask for a plot of any and all the temperature data sets against the CO2 single unbelievably reliable data set. See what you get. Then we can talk about possible harm.

  3. 103
    Jim Larsen says:

    Victor said, “1. we can’t really say for sure, but it looks like we’re dealing with AGW, because there just doesn’t seem to be any other explanation for the radically increased warming since 1850 (hiatus or not). AND 2. we just can’t afford to take the chance that AGW might not be significant, we have to act as though it were, because the potential consequences of the skeptics being wrong are just too dire.”

    Victor, would you take a 100-1 bet that AGW is no big deal? Another 100-1 bet that AGW was not the primary cause of the warming from 1880 to present?

  4. 104
    Chris Dudley says:

    “There is another more elegant way to show this, and it is called change point analysis (Fig. 4). This analysis was performed for Realclimate by Niamh Cahill of the School of Mathematical Sciences, University College Dublin.”

    It looks to me as though this technique is misapplied in addressing the present question because it is not the most sensitive method to find a change near an end point of a time series. I think that a significant change might require twice as much data with this technique to detect than with some other possible approach.

    I think also that the argument that there is not a significant difference between the fitted slope of a subsection of data compared to a larger portion containing that data needs elaboration since the slope estimates are mathematically mixed and not independent.

    Using Kowtan’s tool and some cherry picked start and end dates and the regular HADCRUT data set, I get for 1974-1999 0.203pm0.071 (2 sigma) C/decade and for 2002-2015 0.006pm0.151 (2 sigma) C/decade which (absent the by-hand tuning) would start to look significant. This suggests that there may exist an unbiased tool that could notice a 2 sigma change in behavior.

    As Eric points out (#86), the behavior is at least intriguing and is getting attention from serious scientists. The present treatment seems to miss that aspect owing, I think, to insensitive mathematical treatment.

    [Response: The problem with this approach seems to me that you use disjoint trends, i.e. the end points of such trend lines do not fit together, so that this does not just assume a change in trend but also a sudden jump in-between. This is why the proper change point analysis makes sure that the trend lines join up at the ends, as you can see in Niamh’s graph. – stefan

  5. 105
    Victor says:

    [My second try. Hope this one gets through]

    #103 Jim Larsen

    “Victor, would you take a 100-1 bet that AGW is no big deal? Another 100-1 bet that AGW was not the primary cause of the warming from 1880 to present?”

    Interesting proposition. The only problem: there will never be any way to determine with any degree of certainty that fossil fuels were not a significant cause of any warming. So even if post-hiatus temps go up, we’ll have no way of knowing for sure what caused it. And since there will always be extreme weather events in the future, as in the past, that won’t be much help either. Thus no one could ever win such a bet. Of course each side will, no doubt, at some point claim victory, but the other side would insist on waiting another 20 or 30 years, just to be sure.

    As far as the real world is concerned, the worst of the problem has to do not so much with the bet as with the ante. If it were just a matter of a gentlemen’s agreement that one of us would pay up at some indefinite point in the future, then that’s not too bad. But what the world is now being asked to do is ante up a very considerable sum, in both monetary and life style terms, in order to get in on the action at all.

  6. 106
    Nick Gotts says:

    “Now, ask for a plot of any and all the temperature data sets against the CO2 single unbelievably reliable data set. See what you get.” – rd50@102.

    This would only be a valid point against consensus climate science if climate scientists claimed that atmospheric CO2 levels were the only factor influencing surface temperatures. They don’t.

  7. 107
    Chris Dudley says:

    Stefan (#104),

    In the example I gave, the trends would intersect. The problem there is that the endpoints are selected to seek significance so the calculated significance can’t be trusted. But, I think you must have a continuation of the data for the change point method to work at all which limits the range over which it can have sensitivity to the interior of the data set. To know if a hinge is angled with respect to the door frame, the change point analysis needs to look at the door attached to the hinge. I suspect another method (and not my example) could look at the hinge (and door frame) alone. But, even if we can’t come up with that method, the change point method perhaps should not be used to make claims about end points.

  8. 108
    MarkB says:

    @DF @90,94,100

    I’m not clear on why you think heat capacity is relevant to compiling a temperature anomaly record. It is clearly relevant if one is interested in compiling an energy anomaly across different materials, e.g. “What portion of a global energy imbalance went into the atmosphere”. A temperature anomaly is simply current temperature minus some reference temperature without regard to the material being measured.

  9. 109

    #100–OK, DF, you just blew my mind.

    They are constructing a dataset of observed temperatures. The objective is to have a comprehensive and reasonably homogenous temperature field. They start with temperatures, and end with temperatures. What on Earth are they going to do with specific heat data?

  10. 110
    tamino says:

    Re: #104 (Chris Dudley)

    There’s another problem with your analysis. You’re not just cherry-picking for one trend, but for two. But both have extreme impact on statistical significance (change-point analysis is designed to deal with it), and two combined will wreak havoc squared. If you’re really interested, read this.

  11. 111
    tamino says:

    Re: #107 (Chris Dudley)

    Yes, in your example the trends would intersect *if extrapolated*. But they don’t intersect at either endpoint. Besides, to get that result you have to cherry pick not one but two intervals, and then ignore the data in between.

    I suggest that this kind of analysis is tailor-made to get faulty results, even when done unintentionally.

  12. 112
    Mal Adapted says:


    Look at it this way. You need NO statistical analysis for the CO2 data. You have a pair of eyes and a brain. Linear increase in CO2 concentration from 1958 to now is obvious. Now, ask for a plot of any and all the temperature data sets against the CO2 single unbelievably reliable data set. See what you get. Then we can talk about possible harm.

    How’s this?

    And then there’s physics. Now can we talk about harm?

  13. 113
    CharlieT says:

    It is clear from Gavin’s graph that it is not warming any faster now than it was up to 1940.
    Why is that?

  14. 114
    SecularAnimist says:

    Victor wrote: ” there will never be any way to determine with any degree of certainty that fossil fuels were not a significant cause of any warming.”


    We already know that burning fossil fuels is THE “significant” cause of the increased CO2 concentration responsible for the warming that has already occurred and that will continue to occur.

  15. 115
    Steve Fish says:

    I see that my link at ~#101, 9 Dec 2014 @ 3:55 PM is broken. Just copy the whole thing into your browser. I tried this and it works. Steve

  16. 116
    Steve Fish says:

    Re- Comment by Victor — 10 Dec 2014 @ 11:26 AM, ~#105

    Is this statement- “But what the world is now being asked to do is ante up a very considerable sum, in both monetary and life style terms, in order to get in on the action at all” -just another of your uninformed opinions? What is the ante? There has been quite a bit of analysis of the potential costs and benefits of staying with fossil fuels and transferring quickly to renewable energies. I would be interested in your “detailed analysis” that supports your assertion. Why don’t you review several of the large studies, pro and con, performed by reputable individuals and agencies. Surprise me.


  17. 117
    DF says:

    The web page referred to in this post contain temperature data series for three different measurands: Land / ocean (sea surface and air) , land (air) and satellite (troposphere). It would be nice to know which one of these is the most relevant to use to document global warming? And why is that one measurand more relevant than the two others?

  18. 118
    Victor says:

    #97 Hank Roberts, quoting Hilbert, in 1930: “We must not believe those, who today, with philosophical bearing and deliberative tone, prophesy the fall of culture and accept the ignorabimus. For us there is no ignorabimus, and in my opinion none whatever in natural science. In opposition to the foolish ignorabimus our slogan shall be: Wir müssen wissen — wir werden wissen! (‘We must know — we will know!’)”

    Bad example, Hank. Gödel proved him wrong the following year.

    The real problem is not the ignorantia of the “deniers,” but an unfalsifiable hypothesis.

  19. 119
    Victor says:

    #116 Steve Fish

    “There has been quite a bit of analysis of the potential costs and benefits of staying with fossil fuels and transferring quickly to renewable energies. I would be interested in your “detailed analysis” that supports your assertion.”

    See here:

    Also here:


    and here:

    Aren’t you glad you asked? :-)

  20. 120
    DF says:

    @ 108 MarkB ( @ 109 Kevin Mckinney)

    You got got my point in saying: “It (heat capacity) is clearly relevant if one is interested in compiling an energy anomaly across different materials, e.g. “What portion of a global energy imbalance went into the atmosphere”.
    I would think that if all accumulation of energy goes into the atmosphere heat capacity will not be relevant. If the accumulated energy goes into both the oceans and the atmosphere, and is also transferred between oceans and atmosphere over time, heat capacity will become relevant.

    Further to this, the land / ocean temperature data series seems to be combining measured water (sea surface) temperature and air temperature. In doing that it is implied that accumulated energy both goes into oceans and air, and is transferred between oceans and air. That makes me wonder how water and air temperatures can be combined in these temperature data series without taking into account the heat capacity of the water and air involved in the considered system.

  21. 121
    John E Pearson says:

    It looks to me like there’s just one 17 year “hiatus” after another. The thing I can’t understand is why the so-called APS “framing” document asserts that such “hiatuses” are “rare.” I read that, didn’t believe it, spent 5 minutes on Wood For Trees. I guess it is too much to expect big shot “scientists” like Lindzen, Christy and Curran can’t be to actually spend 5 minutes to check their science? Jeez. I mean it isn’t like I had to stand on my head to find a trend line similar to the one since ’98. The very next 17 year period down the pike has a very similar trend line. The plot is for UAH but the others are similar. If this is a repost sorry. I thought I had posted something like this earlier today but don’t see it.

  22. 122
    Chris Dudley says:

    tamino (#110, 111),

    Yes, both are selected so neither has a reliable estimate of what the significance is in the data generally. However, on your second point, if you look at fig. 4. the fits in the green stripes appear to be splines of some sort so the linear trends are disjoint there as well.

    Extending the GISTEMP data out to 2018 with a 1979 start point did get a break point at about 2006 with this kind of analysis though not so stopping at 2014.

  23. 123
    Keith Woollard says:

    Always worth reading The Bore Hole when more contentious posts go up :-)

  24. 124
    Hank Roberts says:

    > Victor … Hilbert … Gödel

    Oh, please. Wikipedia would like to help you.

    Hilbert’s problems form a list of twenty-three problems in mathematics published by German mathematician David Hilbert in 1900. The problems were all unsolved at the time….
    … Several of the Hilbert problems have been resolved (or arguably resolved) in ways that would have been profoundly surprising, and even disturbing, to Hilbert himself.

    Gödel’s second incompleteness theorem: an inconvenient truth.
    Those results do happen. Scientists learn to live with that kind of result.

    “Science is organized common sense where many a beautiful theory was killed by an ugly fact.” – Thomas Huxley

  25. 125
    max stavros says:

    Regarding autocorrelation in annual data series, out of curiosity I did a simple one step lag test on the HADCRUT4 annual data series and found a significant correlation coefficient ?

    [Response: You need to test for auto-correlation in the residuals from the trend line. – gavin]

  26. 126
    Steve Fish says:

    Re- Comment by Victor — 10 Dec 2014 @ 4:55 PM, ~#119

    Victor, yes I am glad to find my suspicions to be correct but sad that you just don’t get it. Your response is to link your own blog on which you have posted no relevant data and no data analysis, just uninformed opinion. The links below will get your education on the substantive issues started, there are many more.

    Thanks to Patrick 027, Secular Animist, and others for providing this information on Real Climate in the past. (If the links break, just copy and paste.)

    Happy reading, Steve

  27. 127
    Ray Ladbury says:


    Stop digging.

  28. 128
    wheelsoc says:

    I read Tamino’s follow-up and it got me thinking: what would the world have to look like over the last 15 years in order to show a statistically significant, flat trend? One which we could describe confidently as a real (no matter how temporary) change from the previous trend?

    Wouldn’t the temperatures actually have to drop over the intervening years in order to show a signal strong enough to be separated from the noise in such a short set of data?

  29. 129
    Hank Roberts says:

    > Victor
    here, there, and elsewhere, reposting links to himself.

  30. 130
    Victor says:

    #126 Steve Fish

    Oy, that’s a whole lot of heavy reading, Steve. My blog posts are designed for laymen, not engineers. All I can say is: I really wish all those rosy assessments were accurate — and politically viable. I too am in favor of sustainable energy projects — the more the better and the sooner the better. And yes I’d love to see us cut down drastically on coal, oil and gas burning. Those are all pollutants and the world would be better off if we could do without them, or at least minimize their use. I’m on your side on almost all such proposals.

    However, when people start seeing their fuel bills, electric bills, food bills, heating bills, etc. start to soar into the stratosphere, and when millions of third world villagers and tribals begin to die of cold and hunger, then none of that will matter.

    We’ve just learned that the California drought had nothing to do with global warming. And I’ve seen the AMS report regarding the Australian drought, which also has nothing to do with global warming. Same with a great many extreme weather events studied in that report. The best g.w. could do was trigger some uncomfortable heat waves.

    This is the problem when you become conditioned to getting your information from data tables, graphs and statistics. The real world around you becomes just a kind of vague blur and you fail to get how most people manage to survive on a day to day basis.

    To accomplish what you (and I too) would like, ideally, to achieve, you’d need, first of all, the sort of totalitarian state that would make George Orwell positively drool. And on a worldwide basis, literally a police state that would close down certain industries, force millions out of work, insisting that poverty is wealth, cold is warmth, and blackouts are recreational opportunities.

    Pie in the sky by and by. NOT gonna happen.

  31. 131
    DF says:

    @ 109 Kevin McKinney

    With reference to the selectively picked (just to illustrate my point) quotes below, I would say that it is relevant to consider energy when we consider warming. When we consider energy in a system consisting of masses of water and air, I really cannot imagine how it would not be relevant to consider heat capacities. Else we can underestimate the amount of energy accumulated in the system. I further think we should have a close relation between the output of the models and the measurand we use to illustrate or validate the models.

    From skeptical”The Hiroshima atomic bomb yielded an explosive energy of 6.3×1013 Joules. Since 1998, our climate has already absorbed more than 2 billion such bombs (4.0 every second) in accumulated energy from the sun, due to greenhouse gases, and continues to absorb more energy as heat each and every day.”

    An apparent hiatus in global warming?” by Kevin E. Trenberth: “An energy imbalance is manifested not just as surface atmospheric or ground warming but also as melting sea and land ice, and heating of the oceans. More than 90% of the heat goes into the oceans and, with melting land ice, causes sea level to rise.”

  32. 132

    #120–DF, it seems to me that the answer is that the datasets we are talking about are only concerned with temperature, not energy. The measured temps are what they are; it’s only necessary to be sure that they are made as homogeneously as possible, and failing that, to make the best corrections possible so as to avoid bias. You don’t have to be concerned with energy fluxes and specific heat.

    If, on the other hand, you want to study the energy flows, then yes, you need to account for specific heat and a whole bunch of other stuff that I probably can’t even imagine, but which the likes of Trenberth and Fasullo grapple with all the time.

  33. 133
    Dan S. says:

    re: 130. “We’ve just learned that the California drought had nothing to do with global warming.

    Oh brother. Absolutely wrong interpretation, to no one’s surprise. As several climate scientists have clearly stated in the past several days, drought is *enhanced* by climate change. Climate scientists have *not* claimed the drought was caused by climate change. For starters, see The NOAA report is not a peer-reviewed document (so typical of deniers to desperately grab onto non-peer reviewed reports, magazine writers or even science fiction writers for pathetic attempts of affirmation). Also see for Michael Mann’s superb comments.

  34. 134
    Chris Dudley says:

    wheelsoc (128),

    I’ve been thinking about this. It seems to me that this is similar to fitting a spectral line at the edge of an order where the line profile is not completely covered. You use you knowledge of instrument response function and intrinsic line wavelength to make an estimate. In this case, we know that what we are looking for is intrinsically flat, so we should not be fitting a slope at all. We should also probably insist that the ramp plus plateau end up as two legs of a triangle with the base having the slope of a single linear fit. I think this would fit only one additional parameter rather than two. Then perhaps the goodness of fit using chi-square can be compared to estimate if the improvement is persuasive.

  35. 135
    Steve Fish says:

    Re- Comment by Victor — 11 Dec 2014 @ 5:16 PM, ~#130

    You say- “My blog posts are designed for laymen, not engineers.” First of all, this is science not engineering. Second, if you wish to prepare blog posts for laymen, you have to first understand the science. You are concerned about becoming “conditioned to getting your information from data tables, graphs and statistics,” but you are referring to the real world studies of researchers and economists who actually understand the data they present.

    You are also concerned about energy costs going up for us and for the third world, but you can see from the research I linked that this is not necessarily a problem, especially for “villagers and tribals.” There is nothing in the links I provided that has any relationship to “George Orwell,” a “police state,” or anything that forces “millions out of work.” Analyses of many economists (some Nobel Prize winners) who have studied this problem think that a switch to renewables would energize our economy. Alternative energies are already very close to being less expensive than fossil fuels and are much less expensive if you include externalities (look it up). The switch would be a benefit to a large group of local skilled and unskilled laborers and would stimulate the world economy while reducing the problem of global warming.

    You don’t agree? You had better study the real analyses of the problem if you wish to be accurate and creditable. Steve

  36. 136
    MartinJB says:


    your post at 130 (11 Dec 2014 at 5:16 PM) is an absolute mess.

    Let’s see, in paragraph one sets up your perspective. You’d love to see alternative energy. Gosh! You’re not just a knee-jerk petro-apologist.

    Then it goes off the rails. In the second paragraph we learn that all those alt energies are gonna cause the costs of, like, everything to “soar into the stratosphere”. Presumable, you’ve done at least 30 minutes of reading to know that this is going to happen. And somehow, efforts to make sure the developed world and emerging carbon-heavy economies switch to them are going to cause villagers and tribals in the third to starve and freeze. Let’s ignore that no-one is telling them to shut down their diesel generators or else. Just not happening. In-so-much as their actions are even material to preventing climate change, a lot of work is going into HELPING them leap-frog to more efficient and cleaner energy sources – sources that are often long-run cheaper and more reliable for them. And let’s also ignore that many of these people are the ones that will be the most impacted by climate change. Betcha the folks standing in the way of mitigating climate change aren’t gonna be the first in line to help out when rising temps and sea level cause some REAL unpleasantness and mass displacement.

    And the in the third paragraph we learn that you like to draw your own conclusions from papers. Does the phrase “absence of evidence is not evidence of absence” mean anything to you? And my favorite: “The best g.w. could do was trigger some uncomfortable heat waves.” Wow. In one paragraph you’re lamenting the fate of villagers and tribals, and in the next thousands of people dying due to unaccustomed heat waves are just the victims of discomfort. LOVE it!

    And how your fourth paragraph connects to the third (“This is the problem when…”) is beyond me. Why being “conditioned to getting your information from data tables, graphs and statistics” would cause one to misjudge the impact of climate change on extreme weather events is a poser. And to suggest that Steve Fish has been so conditioned seems to be getting a little ahead of yourself (Or do you know him outside of this blog? THAT must be it.). Not that that ever seems to have stopped you before… And to say that anyone here is less aware about how most people manage and survive than you are is pretty insulting and presumptuous.

    And your final paragraph is just utterly contradicted by what’s actually happening in the real world. Amazing strides ARE being made in replacing fossil fuels in ever more efficient ways and in ever more places. And it’s often being done for economic reasons before even taking into account the benefits of mitigating climate change. (BTW… that does not mean that I think that some of the papers showing how we can accomplish truly wondrous things with at most marginal costs are not sometimes overly optimistic. My experience and my work with people who are actively pursuing these goals suggests that some of them might be a tad idealized. But it’s a matter of degree, and I never bet against the ability of highly motivated people to accomplish surprising things!)

    But go ahead and keep your straw-men. Write about them and all your misconceptions about data analysis all you want in your blog. But bring all this here here and you will be called out.

  37. 137

    “The best g.w. could do was trigger some uncomfortable heat waves.”

    – See more at:

    The two largest of which seem to have taken “uncomfortable” to lethal levels for over 120,000 unfortunate souls:

  38. 138

    #131–“When we consider energy in a system…”

    That’s the thing, DF–we weren’t. You asked about the construction of temperature data sets. I answered as best as I could.

    Do you wish to ask another question now? If so, what is it?

  39. 139
    Victor says:

    #129 Hank Roberts

    You are a real piece of work, Hank. Congratulations, you’ve “outed” me. I wonder how long it took. Even a complete idiot would have been able to figure out who I am, simply by spending a bit of time on my blog, where my name is out there for all to see. I have nothing to hide and am certainly not ashamed of anything I’ve written anywhere, ever. Oh, and by the way: it’s actually Rumpelstiltskin. The name you found is a pseudonym.

    And yes, I placed links to my blog in all sorts of places. I hadn’t posted anything new there for roughly two years, and wanted people to read what I had to say. Pardon me for being so pushy.

    I posted here initially as part of that same effort to publicize my blog. But since so many of you insisted on responding here, I replied here. I never expected to win any popularity contests on this particular site, obviously. So the rude and emotional responses I elicited weren’t much of a surprise. And they certainly didn’t discourage me, as you may have noticed. But I must admit I WAS surprised by the extremity of the anger and defensiveness. I expected something better from people who call themselves “scientists.”

    As for the rest, I stand by what I’ve written. And if you disagree, fine. It’s a free country, as they say. But don’t try to snow me with all the “science” blather. Climate change has become a political issue, and as such is open to discussion by anyone.

    As far as the California drought is concerned, according to the report in question, “The current drought is not part of a long-term change in California precipitation, which exhibits no appreciable trend since 1895.” Droughts in California are nothing new. Neither are forest fires. The report also stated: “Nonetheless, record setting high temperature that accompanied this recent drought was likely made more extreme due to human-induced global warming.” When Michael Mann called Seager out on that, his response went something like this: “Farmers in California are praying for rain. I don’t think they care whether it’s getting any cooler.” Excellent retort.

    [Response: “Retorts” are not science. That anomalous heat exacerbate the impacts of rainfall deficits seems pretty basic to me. PS. The response was to Joe Romm, not Michael Mann. – gavin]

  40. 140
    Victor says:

    #137 Kevin

    As for that Russian heat wave:

    “The 2010 Russian heat wave that killed thousands and cut into that country’s grain harvest was primarily due to natural variability, not human-spurred climate change, U.S. scientists said on Wednesday.

    There was plenty of circumstantial evidence pointing to human-caused greenhouse gas emissions and the resulting rise in carbon dioxide in the atmosphere, but close investigation showed this was not a major factor, the scientists said in research published online in Geophysical Research Letters.”

    The above is a quote from Reuters, NOT some “denialist” website.

    [Response: Read the actual papers: links here: – gavin]

  41. 141
    Ray Ladbury says:

    Victor, the concern troll says: “However, when people start seeing their fuel bills, electric bills, food bills, heating bills, etc. start to soar into the stratosphere, and when millions of third world villagers and tribals begin to die of cold and hunger, then none of that will matter.”

    Jebus! Who’s the fricking alarmist now? Victor, allow me to introduce you to what is evidently a new concept for you: evidence. If you supplement your baseless assertions with this commodity, it will render your posts considerably less vapid.

  42. 142
    Chris Dudley says:

    Hi tamino (#110),

    Just a thought on your link. A high p value would be an indication of the existence of a plateau, one gets a similar issue with r going to zero for a flat line even if the “fit” is perfect. So, neither measure is really helpful if one wants to know it the plateau picture describes the data better than a fit with a single slope.

  43. 143
    Jim Eager says:

    Victor wrote: “when people start seeing their fuel bills, electric bills, food bills, heating bills, etc. start to soar into the stratosphere”

    Victor fails to understand that the true cost has always been much higher, but that it was being passed on to the next generation to pay. That IOU is now coming due, and nature always collects in full, plus interest.

  44. 144
    Hank Roberts says:

    > “outed” me

    You posted links to your blog.
    Put the name of your blog into the Google search box.
    It finds the places the name of your blog appears.
    You posted those links.
    Google found them.

    If you were trying to keep your name confidential and I “outed” you by searching for what you post, I do apologize.

    You should realize that Google finds what you post in public and takes people to that material, no matter how long ago you wrote it.

    You are entitled to keep your name confidential — but you have to ask Google to hide it for you.

    Again, if you wanted your name kept secret — ask Google to remove the posts that you did under your name that include the name of your blog.

    Sorry. But seriously, this is how the Internet works.

  45. 145
    Hank Roberts says:

    PS for Victor, you wrote

    Congratulations, you’ve “outed” me. I wonder how long it took.

    You WONDER how long it took?

    Google tells you how long it took.
    Your blog name in the search box.

    You’ll see:

    About 2,400 results (0.44 seconds)

    Ask a librarian for help.

  46. 146
    Hank Roberts says:

    Let’s check that excerpt:

    “The current drought is not part of a long-term change in California precipitation, which exhibits no appreciable trend since 1895.

    … Nonetheless, record setting high temperature that accompanied this recent drought was likely made more extreme due to human-induced global warming.”

    Comments abound; here’s one from AGU’s blogs:

    <a href=""Beware the Juice of Freshly Picked California Cherries

    Dr. Marshall Shepherd, past President of the American Meteorological Society, posted these wise thoughts on his Facebook page this evening:

    “Some broader perspective on this recent NOAA report out this week.. What I see happening is opposing sides of the climate issue are cherry picking perspective from the report. My perspective. I think the study captures aspects of natural variability that would contribute to the West’s drought (La Nina, ocean/SSTs, precipitation, etc.). However, I think it significantly downplays some other aspects . Key points being overlooked: The authors acknowledge climate change and its anticipated effects on drought. They conclude it is not main driver of the current West drought but never conclude human-caused climate change is not happening. They note that this report is not settled. They really didn’t consider the Arctic Amplification hypothesis. Let’s not make too much of this report, but let’s not discount key pieces either. Scientists actually know how to consume a report like this, but there are so many non-experts in the discussion that are not trained as scientists that they take these reports like court reports or a business decision. Science doesn’t work on the premise of reasonable doubt….And, we must end the era of “1-study/1-report” hysteria…”

    He is absolutely right. Science moves forward by a preponderance of the published work, not he said/she said, and especially not when they have a political axe to grind.

  47. 147
    Victor says:

    #144 Hank Roberts

    If it was important to me to keep my name secret I would have left it out of my blog. And avoided doing all those things you mentioned. So no, you didn’t really out me. Which is why I put the word in quotes. I’m not accusing you of anything except revealing your own lack of cool.

  48. 148

    ##140–An adroit change of subject, particularly since the tangent is fairly germane–but still, a change of subject. You were talking about–that is to say, ‘minimizing’–the effects of heat waves.

    Am I to take it that you now concede that heatwaves can be a good deal more than ‘uncomfortable?’

    But let’s talk about the attribution issue a bit. Yes, one study found that the proximate causes of the Russian heatwave had to do with atmospheric circulation patterns. But other studies reached the conclusion that climate change *did* in fact have quite a bit to do with that heatwave–even leaving aside the real possibility that the blocking events inducing the the heatwave are connected to climate change, possibly via decreasing sea ice.

    Might as well recall, too, that on the other side of the system came disastrous Pakistani floods which killed, IIRC, several hundred people and cost the shaky economy several billions of dollars. And that’s important even beyond strict attribution, because we know that both heatwaves and extreme precipitation events are increasing under the warming observed so far–heatwave stats are robust globally, and while the extreme precip stats are only robust for North America, the reason is highly likely to be simply inadequate records elsewhere. That would imply that the same thing is happening around the world, but we don’t yet have the evidence outside North America to prove it.

    So, whether or not the attribution of the Russian heatwave to global warming holds up, it is still significant as an example of what we are going to see more and more often. And it’s a good deal worse than just ‘uncomfortable’.

  49. 149
    Jim Larsen says:

    105 Victor said, “But what the world is now being asked to do is ante up a very considerable sum, in both monetary and life style terms, in order to get in on the action at all.”

    You’re assuming that the asking is optional. It’s not. We take the plunge either way. Unless you’re supporting better than 10-1 no problem, then Houston, we have a problem.

  50. 150
    Victor says:


    Here’s my evidence:

    “The number of cars on the world’s roads surpassed one billion last year . . .” Huffington Post, 2/13 ( Only a small fraction are electric.

    “Coal generates 44% of our electricity, and is the single biggest air polluter in the U.S.” Union of Concerned Scientists (

    “According to the IEA Clean Coal Centre, there are over 2300 coal-fired power stations worldwide (7000 individual units).” World Coal Assoc. (

    13,571 million gallons of airline fuel were consumed by US carriers alone between Jan. and Oct. 2014. (

    “From diesel engines to cow-dung cook fires, soot from inefficiently burned fuel has supplanted methane as the second most significant global-warming agent that humans are pumping into the air, according to an exhaustive review of more than a decade’s worth of research on black-carbon soot emissions. . .

    The new study estimates that in 2000, humans injected soot into the air at a pace of about 7.5 trillion tons a year globally.” (

    “Between 1980 and 2010, global consumption of dry natural gas rose from 53 trillion cubic feet (Tcf) to 113 Tcf.” (

    “Globally, ruminant livestock produce about 80 million metric tons of methane annually, accounting for about 28% of global methane emissions from human-related activities. An adult cow may be a very small source by itself, emitting only 80-110 kgs of methane, but with about 100 million cattle in the U.S. and 1.2 billion large ruminants in the world, ruminants are one of the largest methane sources.” (


    Do you actually want to claim that the fossil fuel and methane emissions represented above can reasonably be cut by any significant percentage over the next 20 years without major disruptions, economic, social and political? Do you really think renewable energy technology will be ready to replace fossil fuels, methane and black carbon over such a brief period? And even if the technology does manage to advance sufficiently, all those vehicles, power plants, heating systems, cookstoves, etc. will need to be replaced in a manner efficient enough so that billions of lives will not be unduly disrupted, not to mention destroyed. You can quote all the facts and figures you like, but that’s just not going to happen.

    As for the projected costs of climate change if less drastic methods are adopted, those are merely projections, while the disruptions now being proposed would, if adopted, become very harsh realities in a matter of a few years — and will certainly have to be imposed “from above.” You might want to wail and gnash your teeth over the inability of humankind to sacrifice short-term for long-term gains, but that won’t change human nature. Fortunately.