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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:

trend3

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.
TempCP3

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. 151
    Ray Ladbury says:

    Victor,
    All you have done is summarize current energy consumption. That is not evidence for your contention, but then, you have demonstrated a complete lack of understanding of what constitutes scientific evidence in every post you’ve made here–as well as those in the Guardian.

    Given your level of ignorance, you might want to do more reading and less writing.

  2. 152
    Dan S. says:

    re: 149. The exact same utterly-failed arguments were made in the US when the 1990 Clean Air Act Amendments required substantial acid rain precursor emissions to be reduced. They were. A lot. And guess what? The economy boomed throughout the 1990s.

    BTW, CO2 emissions have already decreased significantly in the US over the past years while the economy has grown stronger. Due to more efficiency, cleaner combustion, and cleaner fuels.

    In short, your comment has absolutely zero credibility. None at all. And btw, in 1990 the business community wailed about doom and gloom approaching if the Clean Air Act was passed. The US government estimates were quite the opposite. Guess what? The government estimates were spot on. We already have past history to show that, yes, it is “going to happen” because it worked.

  3. 153

    #149–Victor, none of your evidence is to the point at all. Zero. Zip. Nada.

    Everything posted shows that there is lots of carbon pollution. Well, yes. That’s kind of what worries us–remember?

    But the relevant question is, what can be done about it? And you present–may I say it again?–nothing that even bears on that issue. All you’ve got is “do you actually want to claim”, “do you really think”, “even if” and, finally, “that’s just not going to happen.” Pure rhetoric, and pure assertion. Pretty disappointing for a comment that starts “here’s my evidence.”

    Wake up and smell the coffee: even with existing high subsidies on fossil fuels, renewable energy has been expanding exponentially for years:

    http://s1108.photobucket.com/user/brassdoc/media/PV-Growth.png.html?sort=3&o=2

    Less up-to-date, but still indicative:

    http://s1108.photobucket.com/user/brassdoc/media/GlobalInstalledWindPowercopy.png.html?sort=3&o=30

    Energy efficiency solutions are actually the low-hanging fruit in the grid sphere, and they are increasingly in play, not only at the individual level, but also at the institutional level–means are now being found for bidding in significant efficiency ‘capacity’ into grid-level capacity auctions in several large markets, including PJM, NYISO, and (soon) Ontario’s IESO.

    Does it take leadership ‘from the top?’ Well, of course. That’s kind of in the nature of leadership. But what’s happening is happening in the context of functioning governmental and social systems, including free markets.

    Is it enough? Probably not–yet. That’s one reason we need an effective agreement at the Paris COP next year. Massive as investment in renewables has become (I’ll let nuclear fans speak to investments in that area if they wish), it’s still about an order of magnitude less than investment in fossil fuels. But I do find it encouraging that as much is happening as there is, even at this point where we have (to quote John Paul Jones) “not yet begun to fight.”

    I’ll close with one semi-random selection from today’s Google “News” search on renewable energy trends which has some interesting observations that are well-worth thinking about:

    http://www.dispatch.com/content/stories/business/2014/12/13/as-economy-grows-oil-demand-not-keeping-up.html

  4. 154
    StephenBP says:

    At Victor, #149. “Reasonably cut”. “Significant percentage”. “Major Disruptions”. Basically, you aren’t really saying anything substantive. You are concatenating a series of blobs of mush written in the authoritarian voice, in an apparent attempt to put down people who are surfing the wave that you are trying to stop with your bare hands. What is worse, you are conveniently ignoring the really incontestably major economic, social, and political disruptions that follow when people are drowned in storm surges, lose their homes and livelihoods, and are forced into refugee status when a large storm hits vulnerable coastal infrastructure made significantly more vulnerable by a slight, climate change induced rise in overall ocean level that designers and engineers had not factored into their planning. You have conveniently ignored the incontestably major economic, social, and political disruptions that follow from lost agricultural capacity caused by changing temperature and rain patterns that trace back to climate change. And you have conveniently ignored the ability of many people to dream, innovate, and accomplish the “impossible”. And, what is also a major fault in your little screeds, IMO, is that you have raised the hoary specter of “disruption” when you should have instead examined and expounded on the many faceted, complex jewel known as “change”. Being forced out of buggy whip manufacturing is not exactly the end of the world for people who can switch to manufacture energy collecting and storage devices.

    “Disruption” is a great scare word, but things like cancer and fossil fuel economies really need to be disrupted or they tend to kill their hosts.

  5. 155
    Steve Fish says:

    Re- Comment by Victor — 13 Dec 2014 @ 12:43 AM, ~#150

    You don’t provide any evidence to support your claim and your “do you actually want…” and “do you really think…” statements are arguments from ignorance, a logical fallacy. Also, your ruminations about ruminants are incorrect and demonstrate a lack of understanding. You haven’t been doing your reading, have you?

    Steve

  6. 156
    Everett F Sargent says:

    Well, I have a saying:

    Dumber than a rock as opposed to dumb as a rock.

    Dumb as a rock implies no answer as opposed to dumber than a rock which gives you the wrong answer. If you are the dumbest rock you will always get the wrong answer from said dumbest rock.

    You all can hopefully determine which category you know who falls into.

    As for me, this thread has gone terminally tangential.

  7. 157
    Victor says:

    #146 Hank Roberts

    In my latest blog post I cite two other reports in which essentially the same conclusion regarding the California drought is reached. I know you’d rather not go there, Hank, but for any lurkers who might be interested, here’s the link: http://amoleintheground.blogspot.com/2014/12/california-drought-not-caused-by.html

  8. 158
    DF says:

    @138 Kevin McKinney

    I have no further questions. The temperature data series are what they are and are not supposed to represent a full account over warming or accumulation of energy. I guess it is no problem that they do not consider differences in heat capacities as there are also huge masses (e.g. below ocean surface) that are not represented in these data sets. Changes in temperature deeper below the surface might also be correlated with changes in surface temperatures for all I know. I have also learned that even though the energy is absorbed in the atmosphere, the energy is mainly accumulated in the oceans. Only 1% of the energy is accumulated in the atmosphere. Ref.: IPCC IPCC Fifth Assessment Synthesis Report section 1.1.2 Ocean1.1.2 Ocean: Ocean warming dominates the increase in energy stored in the climate system, accounting for more than 90% of the energy accumulated between 1971 and 2010 (high confidence) with only about 1% stored in the atmosphere (Figure 1.2). On a global scale, the ocean warming is largest near the surface…

  9. 159
    Victor says:

    On the topic of mitigation, I admit it. I’m neither a climate scientist nor an economist. I was applying simple common sense to the strong evidence I cited for our currently heavy reliance on fossil fuels. It looks very much to me that those arguing for the most extreme measures are deluding themselves. Such measures would, first of all, be incredibly destructive if adopted, and secondly, have little to no chance of being adopted, because the great majority of the world’s population simply won’t stand for such measures once they grasp the full extent of the disaster they would precipitate.

    On the other hand, less extreme measures, such as the combination of taxes and cap and trade advocated by Paul Krugman and many others, including our President and, apparently, the UN, might work, and could be very helpful in reducing fossil fuel pollution, so I have no serious objection on that score. Such half measures won’t be enough to satisfy climate change activists, however, and for good reason, because they won’t be nearly enough to prevent the catastrophic consequences predicted by most climate scientists.

    Since I’m not an expert on such matters, I’ll refer you to someone far more knowledgeable than I: http://judithcurry.com/2012/09/12/the-costs-of-tackling-or-not-tackling-anthropogenic-global-warming/

  10. 160

    #159–“…those arguing for the most extreme measures…”

    For example? I truly don’t know who you mean, nor what you think “the most extreme measures” are.

  11. 161
    Hank Roberts says:

    > catastrophic consequences predicted by most climate scientists

    Most climate scientists don’t make predictions; many do describe a wide range of possible future inconveniences following on climate change.

    The history of public health offers some hope, as there are examples of such warnings leading to good choices, although the counterexamples are strong: “Darwin Award winners seem to make little or no real assessment of the risk or attempt at risk management.”

    The Fermi Paradox suggests something like a Darwin Award occurs at the species level.

  12. 162
    StephenBP says:

    I severely criticize Victor’s comments for being unrealistically one sided in terms of analysis, for being insensitive in terms of problem recognition, and for being unimaginative in terms of problem solving. In short, he has repeated many of the tired talking points of the fossil fuel industry, an industry which depends heavily on paternalistic authoritarianism and a completely dependent consumer class.
    Understand this. Fossil fuels are largely a short term convenience for the population, and a source of wealth for the fossil fuel plutocracy. Fossil fuels are continually wasted in overly large and inefficient vehicles, overly large over heated poorly insulated houses and buildings. Fossil fuels are also foolishly wasted in ridiculous hormonal spectacles like NASCAR, drag racing, street racing, mindless tourism, and things like children and teenagers with ATV’s and cars driving all over creation making noise, damaging things, risking injury, losing lives, and creating pollution. None of these activities is necessary for the survival of human life. The vast majority of the fossil fuel being wasted is wasted at the behest of, or through encouragement of and enablement of the fossil fuel industry.

    I am advocating the gradual increase in pressure in the form of taxes and credits to force people in the USA, the most profligate waster of energy on the planet, to start being truly conservative in their energy practices. People in third world nations already survive without much fossil fuel, and they are the best adapted for continuing to live without having to hugely increase their use of this stupid poison.

    I have made several major career changes in my life, so I not without sympathy for the argument that fossil fuel executives, car salesmen, ATV salesmen, oil field workers, coal miners, gas station owners, fuel oil salesmen, and nearly everyone on the planet will have to make career changes down the road. Is it that unrealistic to think that these displaced workers can become alternative energy executives, electric car salesmen, alternative energy device installers, biofuel workers, alternative energy engineers, efficient device manufacturers and a vast number of other jobs that don’t hopelessly pollute and destroy our environmental life support system? The fossil fuel industry, and its paid and unpaid supporters, like Victor, seem to want us to despair at the thought of abandoning our fossil fuel addiction. But I have given up more and more fossil fuel use each year with largely pleasant results.

    So to Victor I say, yes, cutting back on the use of fossil fuels will be frighteningly disruptive, or, as I like to put it, a wonderful change. And the sooner we all start changing, the smoother and less frightening and disruptive the changes will be for us and for future generations of humans. And please notice, I and others like me are not calling for an immediate disruptive termination of all fossil fuel use. What we are calling for is a geologically rapid, but humanly and humanely gradual move away from the worst pollution sources towards readily available replacements.

    Technologically, the reduction in use of fossil fuels is readily achievable, and, but for the machinations of the fossil fuel industry, we would have already have made much of the transition to other energy sources. But it is painfully obvious that what is arguably the largest industry on the planet is not going to willingly go on a program of size reduction without a great deal of steady, concerted, mindful outside pressure. Tumors are like that.

  13. 163
    Jim Eager says:

    Victor wrote: “Since I’m not an expert on such matters, I’ll refer you to someone far more knowledgeable than I”
    as he directs us to a person that seems hell-bent on making themselves a laughing stock of the scientific community by writing:
    “Well, ranking 1998, 2005, 2010 and 2014 as the ‘warmest years’ seems very consistent with a plateau in surface temperatures since 1998.”
    See http://rabett.blogspot.ca/2014/12/plenty-of-trend-at-bottom.html

  14. 164
    Entropic man says:

    Hank Roberts

    The Fermi Paradox implies a Great Filter, a series of pitfalls that a civilisation must avoid if it is to survive in the long run. Read the literature and you will find that the risk assessment has been done. IPCC AR5 and the studies of asteroid impact probabilities are just two.

    The problem is to get the political decision makers to pay attention and do something about it. Perhaps democracy encourages Darwin Award behaviour?

  15. 165
    Victor says:

    #160

    “I truly don’t know who you mean, nor what you think “the most extreme measures” are.”

    “In order to avoid dangerous global warming, we need to reduce global greenhouse gas (GHG) emissions by about 50% by the year 2050.” from Skeptical Science (http://www.skepticalscience.com/global-warming-too-hard.htm)

    According to Naomi Klein, the reduction will have to be 8 to 10 percent a year. (see http://thebreakthrough.org/index.php/programs/energy-and-climate/the-left-vs.-the-climate)

    According to like-minded journalist Chris Hedges, achieving such a goal would require drastic action:

    “Resistance will come from those willing to breach police barricades. Resistance will mean jail time and direct confrontation. Resistance will mean physically disrupting the corporate machinery. Resistance will mean severing ourselves from the dominant culture to build small, self-sustaining communities. This resistance will be effective only when we refuse to do what we are told, when we turn from a liberal agenda of reform to embrace a radical agenda of revolt.”

    For my response, see http://amoleintheground.blogspot.com/2014/11/the-politics-of-climate-change.html

    Activist James Hansen advocates all out development of nuclear energy, a “solution” I regard as extreme, though others may not agree. One single accident in a nuclear power plant could lead to a far worse catastrophe than anything projected for climate change over at least 100 years.

  16. 166
    Victor says:

    #162 StephenBP

    “Fossil fuels are largely a short term convenience for the population, and a source of wealth for the fossil fuel plutocracy.”

    Forgive me if I sound like a shill for the oil industry, but fossil fuels are in fact THE source of modern technological civilization as we know it today, and as it’s developed since the dawn of the industrial revolution. (And no, I’m not a shill, as can be easily discerned from perusing my blog. Imo the oil industry and all the other f.f. industries should be nationalized and a hefty wealth tax imposed on the billionaires who’ve exploited these resources.)

    “People in third world nations already survive without much fossil fuel, and they are the best adapted for continuing to live without having to hugely increase their use of this stupid poison.”

    Not so. Google “black carbon” and you’ll learn why. And while you’re at it, google “methane exhalation.”

    Aside from that, I don’t really disagree with you all that much. See, for example the following post: http://amoleintheground.blogspot.com/2014/10/fossil-fuels-and-common-sense.html

    Oh and a note for Hank Roberts: “See how cleverly I’ve managed to promote my blog? Shameless, isn’t it?”

  17. 167
    John E Pearson says:

    150: US CO2 emissions have dropped about 13% in the last 5 years. Your number on coal is wrong. A decade ago we got 50% of our electricity from coal. Now we get 39%. http://www.eia.gov/tools/faqs/faq.cfm?id=427&t=3

  18. 168
  19. 169
    Victor says:

    #167 John Pearson

    Thanks. I stand corrected. The source I used (Union of Concerned Scientists) is undated and I assumed it was current.

  20. 170
    Steve Fish says:

    Re- Comment by Victor — 14 Dec 2014 @ 5:26 PM, ~# 166

    Victor, with regard to your objection to the assertion that fossil fuel dependence is minimal in the third world, I would really like to hear your explanation of what black carbon and methane exhalation have to do with fossil fuel pollution in the third world.

    Steve

  21. 171
    Hank Roberts says:

    Good example of how doing research sometimes requires going beyond the first page, even on the Internets:

    “Coal generates 44% of our electricity …”

    The page Victor gives as his undated source, which he presumed was current information, starts with a set of brief statements (from which his number came). Each is followed by a link to Learn More

    Below that is a list of links to In-Depth Analysis and Reports
    Each of those has a year date on it.

    In those, they provide a link to their 2013 Full Report Update

    Ripe for Retirement: An Economic Analysis of the U.S. Coal Fleet
    The Electricity Journal, Volume 26, Issue 10, December 2013, Pages
    51–63. Online at: http://dx.doi.org/10.1016/j.tej.2013.11.005

    So, what’s the date of the latest information there?

    “… Since 2009, 20.8 gigawatts (GW) of coal-fired electricity generation has retired, representing 6.2 percent of U.S.’s 2009 coal fleet, and, as of October 2013, another 30.7 GW of coal generators is slated for retirement in the near future.1

    Coal-fired electricity fell from nearly half of U.S. generation in 2008 to 37 percent in 2012 ….”

    (Kids, don’t what I wrote here for a school report: I quit looking at this point; you’d be expected to go further. Hint: follow the footnote. Google wants to be your friend. So does your librarian. One of them is trying to sell you shit, the other wants to see you grow up smarter. Choose carefully)

  22. 172
    Victor says:

    #170

    According to the EPA, “Black carbon (BC) is the most strongly light-absorbing component of particulate matter (PM), and is formed by the incomplete combustion of fossil fuels, biofuels, and biomass.

    BC is emitted directly into the atmosphere in the form of fine particles (PM2.5). BC is the most effective form of PM, by mass, at absorbing solar energy: per unit of mass in the atmosphere, BC can absorb a million times more energy than carbon dioxide (CO2). BC is a major component of “soot”, a complex light-absorbing mixture that also contains some organic carbon (OC). . .

    Asia, parts of Africa, and parts of Latin America (Central and South America) are among the regions emitting the largest amounts of BC. Sources in developing countries are substantially different than in the United States: mobile sources (19%) and open biomass burning (35%) represent a smaller portion of the global inventory, while emissions from residential heating and cooking (25%) and industry (19%) are larger.” http://www.epa.gov/blackcarbon/basic.html

    In the Third World, as I understand it, black carbon is largely produced from the burning of charcoal in simple stoves.

    As for methane, I never said that was a fossil fuel. I just suggested he look it up.

  23. 173
  24. 174
    Chris Dudley says:

    So an unbiased way to look at the question, does a ramp followed by a plateau describe the data better than a ramp alone, seems to run into trouble when looking at p-values or the r statistic since flat lines have no significance and don’t correlate either. So, I’ve looked into reduced chi-square. Reduced chi-square tries to account for the fact that more complex models are going to look better without necessarily being better by dividing the chi-square statistic by the number of degrees of freedom in the fit. So, to be fair to the plateau possibility, we want to keep the degrees of freedom as high as possible rather than fitting extra parameters.

    I’ve taken a two step process. Working with GISTEMP data from 1979 to 2013 I first fit a slope and offset of 1.564 hundredths of degree per year and 12.009 hundredths of a degree with 1979 as year zero. 1979 in an unbiased end point in the sense that Stefan has used it before in a paper. Taking an uncertainty estimate of 7 hundredths of a degree off this figure http://data.giss.nasa.gov/gistemp/graphs_v3/Fig.A2.gif the chi-square estimate comes to 55.7. There are 35 data points and two fit parameters so the degrees of freedom comes to 33 and reduced chi-square comes to 1.69.

    Here is what I used for data which involve some transcription if anyone wants to check for typos.

    y=[12.,22,28,9,27,12,5,14,28,35,24,39,38,19,21,28,43,32,46,61,40,40,52,61,60,51,66,59,62,49,59,66,54,57,59]

    The next step is to introduce the plateau with only one new parameter. Since the slope of the the plateau is by definition zero, that is not the parameter. And, since we’ve already determined the overall slope and average of the data, we may just carry those over and retain them. So, parameterizing on the angle of a triangle with the initially fitted slope as one adjacent leg, the plateau as the opposite leg and the new ramp as the other adjacent leg while insisting that the new fit average match the old fit average gives us a single new fit parameter. The best angle turns out to be about 0.105 radians. Chi-square comes out to 52.0 in this case and dividing by the now 32 degrees of freedom gives a reduced chi-square of 1.63 which is an improvement over 1.69 from the prior fit. The plateau begins in 2006 in this fit.

    I don’t think this statement “…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.” is quite right.

    The reduced chi-square should be closer to one in the first fit if year-to-year fluctuations were fully explanatory. I think decade scale fluctuations owing, in part, to known phenomena are also playing a role here.

    So, I think that recent efforts to look at links between ocean circulation changes and recent surface temperature behavior (the plateau) in not just fitting noise but may have legitimate explanatory power.

  25. 175
    Steve Fish says:

    Re- Comment by Victor — 16 Dec 2014 @ 1:13 AM, ~#172

    So Victor, what exactly is the point of your third world black carbon and exhaled methane response to StephenBP? How much global warming is the third world responsible for?

    Steve

  26. 176
    Victor says:

    #175 Steve Fish asks “So Victor, what exactly is the point of your third world black carbon and exhaled methane response to StephenBP? How much global warming is the third world responsible for?”

    Answer:

    “Soot from tens of thousands of villages in developing countries is responsible for 18 percent of the planet’s warming, studies say.”

    ““It’s hard to believe that this is what’s melting the glaciers,” said Dr. Veerabhadran Ramanathan, one of the world’s leading climate scientists, as he weaved through a warren of mud brick huts, each containing a mud cookstove pouring soot into the atmosphere.” From “Third-World Stove Soot Is Target in Climate Fight.” (http://www.nytimes.com/2009/04/16/science/earth/16degrees.html)

    As for methane from third world cattle, see “Cows with Gas: India’s Global-Warming Problem” (http://content.time.com/time/world/article/0,8599,1890646,00.html)

    “By burping, belching and excreting copious amounts of methane — a greenhouse gas that traps 20 times more heat than carbon dioxide — India’s livestock of roughly 485 million (including sheep and goats) contributes more to global warming than the vehicles the animals obstruct.”

  27. 177
    Callum Villiers says:

    Don’t know if anyone’s posted Victor’s biography before, but this goes some way to explaining why he doesn’t seem to have a clue about climatology or economics, but has a very inflated sense of his own worth. I’m actually very interested in his work with Alan Lomax, and will try and get hold of a copy of his Sounding The Depths. But, Victor, sorry to say this chum, you come over as an arrogant, ignorant, sociopathic clown in these parts.

    Dr. Victor Grauer, based in Pittsburgh, PA, is a composer, author, musicologist, film‑maker, media artist, poet and dramatist. He holds a Masters Degree in Ethnomusicology from Wesleyan University, with additional studies in that field at UCLA, and a Ph. D. in Music Composition from SUNY Buffalo. His creative work has been presented in many venues worldwide, including Lincoln Center (the New York Film Festival), Carnegie Institute (Pittsburgh), The Kitchen (New York), The Mattress Factory (Pittsburgh), the Barbicon Center (London), etc. His writings have been published in journals such as The Mississippi Review, The Little Magazine, The Downtown Review, Yggdrasil, Ethnomusicology, Semiotica, Art Criticism, Music Theory Online, Other Voices, Millennium Film Journal, The World of Music and Before Farming. In 1998 he received the Pittsburgh Cultural Trust’s Creative Achievement Award. Grauer has taught at the University of Pittsburgh, Pittsburgh Filmmakers, the Pittsburgh High School of the Creative and Performing Arts and Chatham College. He is presently engaged in research linking his work with Alan Lomax on world music with current developments in genetic anthropology and archaeology.

  28. 178
    John Buffum says:

    This has little to do with math, at least scientific math. Now, political math is a different animal altogether. “If you don’t accept my way of thinking, you are a xxxxxx” (pick your pariah) Odd that those who do this accuse their victims of close-mindedness.

    Mavens of global warming are not the only cattle in the herd. John Casey, “Cold Sun”, 2011, and “Dark Winter” 2014, presents an alternative view. I am looking for others, as well, not non-scientific whackos, but folks with a scientific career behind them.

    Predicting the future, especially half a century to a century later is a lot of fun, but so much can happen to change the rules of the game. An example is Malthus. DDT changed everything, and rendered his predictions useless.

    A degree C in ten years? So many predictions about the next ten years. From total societal collapse, to ice age, to a period of dizzying prosperity, to “the rapture” and “the tribulation”, to The Third Jihad, to Hillary actually being elected President, to the achievement of Agenda 21. Each could produce a paradigm shift.

    Congrats to all you math folks. Wish I had that kind of smarts. Mine was keeping wireless networks alive. Keep up the good work, but don’t be so fast to be so waspish about those who disagree with you. A few of them may be right.

  29. 179
    Jim Eager says:

    DDT didn’t render Malthus’ predictions useless, John, it just stretched the timeline. So did a lot of other things, but that just allowed us to overstretch different resources in other ways and the timeline is now getting harder and harder to stretch.

  30. 180
  31. 181

    #178–Hmm, “John L. Casey, NASA” doesn’t turn up a bio, oddly enough, but this came up:

    http://mediamatters.org/blog/2010/05/15/hoft-runs-with-global-cooling-warning-from-scam/164798

    And this:

    http://cosmoquest.org/forum/archive/index.php/t-68846.html

    And this:

    http://issuepedia.org/Space_and_Science_Research_Center

    Here’s what the SSRC itself has to say:

    http://www.spaceandscience.net/id64.html

    What’s interesting about this is that it is a falsifiable hypothesis. Mr. (?) Casey has not, according to his initial 2008 report, addressed the greenhouse effect at all. He has simply identified a possible correlation between solar output and global mean temperature. He seems to be assuming in his temperature forecasts that the GE is not operating, and that his correlation will hold up unaltered even though atmospheric GHGs are up over 40% from pre-Industrial concentrations. He therefore expects that:

    As a result of the theory, it can be predicted that the next solar minimum may start within the next 3-14 years, and last 2-3 solar cycles or approximately 22-33 years. Beginning with cycle 24 but no later than cycle 25, sunspot numbers may approach a Wolf number of 50 for each of two consecutive solar cycles. It is estimated that there will be a global temperature drop on average between 1.0 and 1.5 degrees C, if not lower, at least on the scale of the Dalton Minimum. Should the minimum begin with solar cycle 24 as forecast, the bottom of the temperature curve for this predicted minimum is forecast for the year 2031 with widespread record cold for years on either side of 2031. A start at solar cycle 25 would extend the range of the next bottom of the solar minimum to the 2031- 2044 period or more.
    [13] As a result of the predictability and accuracy afforded by the RC Theory, and in the interests of the welfare of the world‟s citizens, the following special note is added: This forecast next solar minimum will likely be accompanied by the coldest period globally for the past 200 years and as such, has the potential to result in world wide, agricultural, social, and economic disruption.

    I find his wording a little confusing because “approach a Wolf number of 50 for each of two consecutive solar cycles” is ambiguous; does he mean that that is the average over the whole cycle, or what? But seeking context, I downloaded the daily Wolf numbers from here:

    http://sidc.oma.be/silso/infossntotdaily

    Taking, somewhat arbitrarily, the mean daily value since Jan 1, 2000 to 11/30/14 (the most recent number), and plugging them into Excel, I find that the mean value over that span is actually 51.26 and change. That’s probably biassed high, since the period includes two solar maxima and only one minimum, as you can more or less see here:

    http://sidc.oma.be/silso/dayssnplot

    But, bottom line, Mr. Casey’s projection for Wolf numbers looks pretty reasonable so far. And that wouldn’t be shocking, as there appears to this layman to be at least some real papers in his bibliography. Some predecessors:

    http://en.wikipedia.org/wiki/Solar_variation#Hypothesized_cycles

    On the other hand, his projection for temperature appears not to be faring so well. We have had a ‘pause’ in which the global mean surface temperature has exhibited only a very weak warming trend; but there is certainly no evidence whatever that we are headed for lows unprecedented since the 18th century. There’s not even any *indication* that that might be true.

    All of which is consistent with the idea that his solar cycles *could* be real (though not all that novel)–but that so is the greenhouse effect.

  32. 182
    Steve Fish says:

    Re- Comment by Victor — 16 Dec 2014 @ 6:18 PM, ~#176

    Ramanathan said that black carbon is responsible for 18% of global warming. My recollection is that its main warming effect is melting snow and ice, while its effect as an aerosol is mixed with warming the atmosphere but cooling the surface from dimming and complicated weather and cloud effects. Black carbon comes from a variety of sources worldwide including biomass burning, diesel exhaust, bunker fuels in ships, and wild fires. Fires in boreal forests are especially influential on overall global snow melt because they are near the arctic. My question was what portion of black carbon warming can be attributed to third world cooking fires. Not so much I think and mostly not dependent on fossil fuels.

    As for methane from cows and other ruminants, there is a lot of misinformation that is easily debunked. The carbon in the methane and CO2 that is released from cow burps and digestion of cow manure by microorganisms comes from the plants that the cows eat, and the plants obtained the carbon from CO2 in the atmosphere. In order to determine if there is any net atmospheric increase in carbon you have to subtract the amount removed from the amount that was subsequently released. Methane is a potent greenhouse gas but it is converted to CO2 in around 10 years. The number of cows in the world has been pretty much constant at around 1.5 billion for the last 10 years, so if this number doesn’t change in the future there would be no methane (or CO2) added to the atmosphere. The portion derived from cows will remain constant.

    Complications of this picture come from the fact that in developed nations, growing cow fodder, and all of agriculture for that matter, utilizes considerable fossil methane (natural gas) to make fertilizer and considerable petroleum for cultivation and transportation. Fossil carbon is not a part of the fast carbon cycle so it adds to the atmospheric greenhouse gas load. In the third world, cows are grazed on lands that are commonly not artificially fertilized, so it is developed nation cows that are adding greenhouse gas to the atmosphere and third world cows are not that important.

    Get to your studying. Steve

  33. 183
    Hank Roberts says:

    Also for John Buffin:

    try ‘oogle for Casey and junkscience —
    Seriously, don’t believe everyone who claims he’s a NASA scientist or White House science advisor. There are a lot of hoaxes out there.

    Check them out. Look for their publications.

  34. 184
    MarkB says:

    | @170
    | Callum Villiers says:
    | 16 Dec 2014 at 7:42 PM
    |
    | Don’t know if anyone’s posted Victor’s biography before . . .

    Cheap shot, red card to Callum Villiers.

  35. 185
    Hank Roberts says:

    PS for John Buffin — remember carrying capacity: for nonhuman species, when any population/local group exhausts any single resource, that population collapses.

    Humans can last longer because we import whatever resource is locally exhausted.

    You should read this, at least:
    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2602943/

    And this:
    http://www.publicbooks.org/nonfiction/changing-climates-of-history

    Drought is common in the Middle East and often disastrous for farmers already operating at the margins of dryland agriculture. But it is mercifully rare that drought affects southwest Asia and the Nile Valley at the same time, because the Nile’s water comes mainly from Ethiopian rainfall, governed by an entirely different weather system than Anatolia, Syria, Mesopotamia, and Iran’s. Thus, throughout the long history of agrarian states and regional trade in the Middle East, when harvests failed in one place, grain could normally be imported from another. Usually it was Egypt that could bail out the rest of the eastern Mediterranean. This insurance against drought helps explain the success of large states in the region. Ellenblum explains the depth of disaster in the 10th and 11th centuries by claiming that, especially in the 1050s, droughts brought harvest failure for years on end both in Southwest Asia and in Egypt, something that, he says, happens on such a scale only once every thousand years or so.

    This perfect storm of simultaneous droughts undermined dynasties in Cairo, Baghdad, and Constantinople. Crops failed throughout the region. States could not collect enough grain and taxes to pay their soldiers and bureaucrats, who rose in rebellion just as desperate herders began riding in from the desert or steppes, searching for food. Urban riots, persecution of minorities, sectarian violence, and refugee movements, among other crises, overwhelmed the struggling states. When the Crusaders showed up in 1099, the region was still recovering from over 120 trying years of famine, rebellion, plunder, and chaos.

    Historians of medieval Western Europe, familiar with what used to be called the Medieval Warm Period, but is now more often termed the Medieval Climate Anomaly (or MCA), will recognize that Ellenblum is arguing for a radically different trajectory in the eastern and western parts of the Mediterranean, and Europe generally. For medievalists attuned to the MCA, its warmth and longer growing seasons help to explain the rising prosperity of Western Europe between 900 and 1250. The contrast with the eastern Mediterranean could not be starker. Ellenblum draws another contrast as well. He claims that medievalists of the western realms need only Latin to read their sources, whereas those of the eastern realms need Arabic, Persian, Greek, Turkish, and Hebrew at a minimum. The linguistic challenges, he says, account for why scholars so far have missed the central role of climate shifts in the political tumult of the medieval Middle East….

  36. 186
    troll says:

    “there never was a significant pause to start with..”
    If there is/was no pause in warming, then why have scientists (and others) offered over 50 different explanations of this non-existent trend?

    [Response: There’s a difference between “something interesting is happening” and “there is a pause in global warming”. The “pause” terminology is unfortunate because it’s misleading (which is why people who want global warming to go away use it). Why do scientists use the term? Some combination of efficiency and naiveté. read. Chris Mooney’s article on this is worth a read. –eric]

  37. 187
    patrick says:

    The article by Chris Mooney shows the Skeptical Science escalator chart, sequentially animated, i.e.:

    http://www.skepticalscience.com/graphics/Escalator_2012_1024.gif

    The animated Escalator is originally here:

    http://www.skepticalscience.com/graphics.php?g=47

    As it says, the concept of the Escalator was originally proposed by Bob Lacatena, #61-63:

    http://www.skepticalscience.com/news.php?p=2&t=68&&n=1074#66528

    Click on graphic in #63 to get original generation by interactive graph generator at Wood for Trees climate data tools.

    http://www.woodfortrees.org/

  38. 188
    Yvan Dutil says:

    Hi, I have used one of this graph for my blog. I think it is refereed properly, but if there is any issue let’s me know.

    http://voir.ca/yvan-dutil/2015/01/16/une-pause-quelle-pause/

  39. 189
    Dave Meiser says:

    Is it possible for you to comment on the recent hype from the skeptic camps which are stating that NASA and others are only About 38 Percent Sure That 2014 Was The Warmest Year On Record?

    Specifically are they using the wrong statistic to attempt to muddy up the waters?

  40. 190
    Mal Adapted says:

    Dave Meiser:

    the recent hype from the skeptic camps which are stating that NASA and others are only About 38 Percent Sure That 2014 Was The Warmest Year On Record?

    Tamino’s answer to the pseudo-skeptics is definitive.

  41. 191
    Thomas Dobson says:

    I would like to know how temp anomalies or the actual reported temps can have any relationship with mean temps .As I understand the process the min and max temps are reported without any reference to time . If I have been misinformed on this please elaborate on the actual process . Thankyou

  42. 192

    #189–Dave, ‘Mal’ is right about Tamino’s response. It is excellent.

    However, I’ll add that I think that the hype is about the dumbest thing ever, and rife with ironies–for example, a common headline, with multiple reblogs, is “2014–Most Dishonest Year.” Yet how have the deniers chosen to frame the probabilistic analysis of the ‘warmest year’ question? Why, with a misleading aggregation of all other ‘candidate years’, combined with a cherry-pick of the NASA number over the NOAA one. Rather dishonest of them, I would say!

    To see what I mean, consider this screenshot of a Climate Depot post:

    http://i1108.photobucket.com/albums/h402/brassdoc/Climate%20Depot%20Spin%20Pic.png

    As you can see, the NOAA analysis gives a 48% chance that 2014 was really the warmest year; for the next most likely year, 2010, the number is 18%. For NASA, those numbers become 38% and 23%, respectively. That, I think, gives a rather different impression of what the supposed “admission” that there are error bars actually means.

    Personally, I think that the sheer disingenuousness of the meme is [yet another] shocking demonstration of bad faith. All measurement has error bars, from stopwatches to hygrometers. How often do we consider them in relation to records, from track results to comfort indices? Just about never. But when the denialists take a hit to their credibility, they will not fail to respond–even if it means blaming NASA for not doing something virtually no-one ever does anyway.

  43. 193

    #191–Thomas, I’m no expert on this, but let me offer a few thoughts, and perhaps some more informed folks will weigh in.

    First, surely it’s obvious that “temp anomalies or the actual reported temps” MUST “have [a] relationship with mean temps”, since at the very least the mean is constrained by the max and min temps–that is, the mean can never be higher than the max, nor lower than the min.

    Second, reporting is, and has not been, the same in every place and time. In the ‘old days’ there were sometimes fixed schedules of observations, often a couple of times per day. But the minimums and maximums were usually measured by the use of a “Six’s thermometer.” Since its operation was completely automatic, there was no way to know just when the max and min occurred.

    But if hourly readings were taken, then obviously you could tell to within less than an hour when each temperature was achieved. And today, that is very often the case, since stations are automated. For example, here’s NOAA’s hourly data page:

    http://www.erh.noaa.gov/pbz/hourlyclimate.htm

    You can see that the record for “NWS Pittsburgh” goes back to the end of August, 1991. (I’m not quite sure why that’s supposed to be the ‘home page’–it’s not obvious to me how you would look for similar records for other locations.) Similarly, though, for stations around the world, from Canada’s “Resolute” station, above the Arctic circle, to ones operated by the Australian Bureau of Meteorology:

    http://www.bom.gov.au/climate/data/stations/about-weather-station-data.shtml

    As that last link shows, “At the majority of locations, Automatic Weather Stations (AWSs) send data frequently. Some provide data every minute, while others report on an hourly basis.”

    So, in the modern record, there is ample information available to properly characterize the relation of the max and min to the time-weighted mean.

    You may not have that for past data you might be interested in, but that’s how it goes. I imagine that you could get a pretty good handle on the question by analyzing the abundant modern data, and use that to constrain the relationship for the past. I frankly doubt there’s any bias to long-term trends resulting from the issue.

    (And I’m quite sure that someone, somewhere, has studied the question pretty exhaustively–probably multiple ‘someones’ and ‘somewheres’.)

    As semi-random closing tidbit, note that NOAA offers real-time (15-minute update cycle), high resolution data for the US, and has been doing so since 2001:

    http://madis.noaa.gov

    “MADIS subscribers have access to an integrated, reliable, and easy-to-use database containing the real-time and saved real-time observational datasets described below. Also available are real-time gridded surface analyses that assimilate all of the MADIS surface datasets (including the highly-dense integrated mesonet data). The grids are produced by the Rapid Update Cycle (RUC) Surface Assimilation System (RSAS), which incorporates a 15-km grid stretching from Alaska in the north to Central America in the south, and also covers significant oceanic areas. The RSAS grids are valid at the top of each hour, and are updated every 15 minutes.”

  44. 194
    Tom says:

    You Climate Scientists need to stop defending your statistical models and TAKE SOME BLAME for the fact that the public doesn’t understand Global Climate Change, or the science behind it. You spend too much time (as in the example shown above) discussing statistics and probabilities and your latest model and not enough time explaining the underlying physics to the public. You debate and debate whether the “Climate Pause” is true or not. But, you ignore the FACT that even if there were a temporary slowdown that that would not necessarily be good news!

    Let me explain what I mean. Simple physics tells us that as you add heat any system, when the temperature od a solid approaches its melting point, apparent temperature rise slows down due to the phase change from solid to liquid. (It’s known as the latent heat of fusion.)

    As you add heat any system, when the temperature approaches the melting point, apparent temperature rise slows down due to the phase change from solid to liquid. That’s simple Thermodynamics 101. (It’s known as the latent heat of fusion.)

    http://www.splung.com%2Fcontent%2Fsid%2F6%2Fpage%2Flatentheat&ei=ULrCVLbuE4ewggSwnoCYDg&bvm=bv.84349003,d.eXY&psig=AFQjCNHl_6UaLYc0U-yNMvK6mGvvbhDZNA&ust=1422134174134460

    So, it would not be the least bit surprising that, as the polar ice caps (and alpine glaciers) have been heated to the point where they grow continually smaller each year (and greater melting occurs each spring), we should expect to see a very apparent plateauing of average global temperature rise. The poles have spent more time in the red zone each year over the past decade (shown in the graph linked above, between points B and C), sucking up excess heat. If more heat goes into melting, then less heat goes into the air.

    So, a slowing in temperature rise compared to rates of CO2 increase is NOT NECESSARILY a good thing! A pause could be a sign that in the future temperature will rise at a rate much faster than in the past. Each year we see higher and higher ocean latitudes with average ocean temperatures entering the area of the graph to the right of the melting zone (meaning that sea ice no longer forms there, because winter average temps are too high). And, that is the zone (between C and D in the graph) where the temperatures start to climb much faster than previously as you add more heat to the system.

    Simple physics. Found in every first year text book. I don’t know why climate scientists have explained these simple facts so poorly. It may be new data, but it’s NOT new science.

    It was foolish for anyone to assume that temperatures would always rise at a rate proportional to CO2 increase. The science does not predict this! Whether there was a pause, or by how much it paused, is completely beside the point! Unfortunately, some climate modelers implied to the press that rates of temperature change in the future would be the same as in the recent past. That is partly because, I think that was the default assumption in their overly simplistic models! Now much of the public believes that any leveling off in temperature increase, while CO2 levels continue to rise is PROOF that the underlying physics is wrong. But, actually the physics predicts these pauses due to increased phase change and feedbacks in the system!

    Implying that we know the rate at which temperature will increase compared to GHG increase by looking at the average rate in the recent past is just wrong! We know it will go up each decade, but climate scientist should not lead people to believe that every year will be hotter than the next that is not what the science actually predicts and when it is not (as it will invariably be in some years), then the public thinks the science is not well understood. Stop over-selling your confidence in the predictive capabilities of your model. It’s not about YOUR MODEL or YOUR STATISTICAL METHODS, its not about what you think you know, it’s about the simple physics of heat absorption and transfer. When there is extra heat absorbed, it has to go somewhere. Period. And as global ice packs decline, the rates of temperature increase will no doubt increase even more rapidly!

  45. 195
    Tom says:

    The link that should have been included in my post above:
    http://www.splung.com/content/sid/6/page/latentheat