The IPCC sees the pause in global warming!

Summary: Today we look at one of the many interesting graphics from the leaked draft of the IPCC’s Fifth Assessment Report (AR5), this one showing the pause in global warming. And the various responses of scientists to this data.  This is the latest in a series about the “pause” in global warming; see section 6 for more information).

Other posts in this series about second order draft (SOD) of the Fifth Assessment Report (AR5) by the Intergovernmental Panel on Climate Change (IPCC):



  1. A powerful graphic
  2. A brief comment about the pause
  3. Three responses to this data
  4. Significance of the pause to non-scientists
  5. The warmistas’ response to the pause
  6. Other posts about the “pause”
  7. For More information

References omitted in excerpts from the IPCC report; red emphasis added.

(1) A powerful graphic

Alex Rawls leaked the draft of the IPCC’s Fifth Assessment Report (AR5). Figure 1.4 shows the actual temperature vs. the forecasts of the IPCC’s various models:

Figure 1.4, draft of IPCC AR5
Figure 1.4, draft of IPCC AR5

Caption to this graphic:

Estimated changes in the observed globally and annually averaged surface temperature (in °C) since 1990 compared with the range of projections from the previous IPCC assessments.

  • Values are aligned to match the average observed value at 1990. Observed global annual temperature change, relative to 1961–1990, is shown as black squares.
  • Whiskers indicate the 90% uncertainty range of the Morice et al (2012) dataset from measurement and sampling, bias and coverage.
  • The coloured shading shows the projected range of global annual mean near surface temperature change from 1990 to 2015 for models used in {FAR, TAR, and AR4}.
  • The 90% uncertainty estimate due to observational uncertainty and internal variability based on the HadCRUT4 temperature data for 1951-1980 is depicted by the grey shading.

The IPCC models shown are:

  • FAR: 1990, the IPCC’s First Assessment Report
  • SAR: 1995, the IPCC’s Second Assessment Report
  • TAR: 2001, IPCC’s Third Assessment Report
  • AR4: 2007, the IPCC”s Fourth Assessment Report

(2)  Update:  A brief comment about the pause

From Chapter 10 – Detection and Attribution of Climate Change:

While the trend in global mean temperature since 1998 is not significantly different from zero, it is also consistent with natural variability superposed on the long-term anthropogenic warming trends projected by climate models.

See the (c) in the next section for more from AR5.

(3)  Three responses to this data

The response of scientists associated with the IPCC to this divergence takes various forms, such as these three.


Kenneth Trenberth
Kenneth Trenberth

(a)  The models are getting better

In AR5, the new models are described as superior to the models used in past IPCC forecasts. But the older models were also presented originally as providing a reliable basis for massive public policy measures.

(b) An infamous defense

Often used, most clearly stated by Kevin E. Trenberth (Senior Scientist, Climate Analysis Section at the National Center for Atmospheric Research), “Predictions of climate“, Nature, 4 June 2007 — Excerpt:

In fact there are no predictions by IPCC at all. And there never have been. The IPCC instead proffers “what if” projections of future climate that correspond to certain emissions scenarios. There are a number of assumptions that go into these emissions scenarios. They are intended to cover a range of possible self consistent “story lines” that then provide decision makers with information about which paths might be more desirable.

But they do not consider many things like the recovery of the ozone layer, for instance, or observed trends in forcing agents. There is no estimate, even probabilistically, as to the likelihood of any emissions scenario and no best guess.

Despite Trenberth’s assertion, the IPCC reports are littered with descriptions of the model outputs as “forecasts”. And their outputs are presented to the public and policy-makers as forecasts, the basis for large-scale public policy action.

(c) The pause is “consistent with” the models

While analytically accurate, statements that such a wide range of outcomes is “consistent with” the models shows that today they provide a weak basis for large-scale public policy action.  See these excerpts from the draft AR5.

Chapter 2: Observations: Atmosphere and Surface

Much interest has focussed on differences in the period since 1998 and an apparent flattening in HadCRUT3 trends. … all products now show a warming trend since 1998

  • HadCRUT: 0.055 °C per decade;
  • MLOST: 0.042 °C per decade;
  • GISS: 0.093 °C per decade.

None of these are statistically significant.

Chapter 10: Detection and Attribution of Climate Change

Global mean surface temperatures have not increased strongly since 1998, a period over which the multi model mean simulated temperature increased in response to steadily increasing greenhouse gas concentrations and constant or declining aerosol forcing. A key question, therefore, is whether the recent apparent slowdown in the rate of observed global warming is consistent with internal variability superposed on a steady anthropogenic warming trend (for example, as represented by the spread of model trends over the same time), or whether it has been driven by changes in radiative forcing. It is found that global temperature trends since 1998 are consistent with internal variability overlying the forced trends seen in climate model projections …

Liebmann et al. (2010) conclude that observed HadCRUT3 global mean temperature trends of 2–10 years ending in 2009 are not unusual in the context of the record since 1850. After removal of ENSO influence, Knight et al. (2009) concluded that observed global mean temperature changes over a range of periods to 2008 are within the 90% range of simulated temperature changes in HadCM3. Over the period 1999–2008, ENSO contributed a warming influence, so the lack of warming seen in the global mean temperature over this period cannot be attributed to ENSO.

(4) Significance of the pause to non-scientists

The pause in global warming, now roughly 15 years long, is clearly seen in the major climate data sets. It has been acknowledged by many prominent climate scientists. It has been the subject of much study in peer-reviewed publications. We look at examples of all three in these two posts.

The pause should not surprise anyone familiar with the current state of climate science. The relative importance of the many causes of the two century-long warming remain uncertain (only since 1950 has anthropogenic CO2 been the largest driver). There are many factors at work: natural cycles, volcanoes, solar cycles, emissions of CO2 and aerosols, land use changes — and feedbacks (eg, warming on atmospheric humidity). Some of these are poorly understood. This makes reliable forecasts difficult, especially to the degree required before re-shaping the world economy.

That’s the import of the pause. The long warming will resume, continue, or end. Climate scientists will analyze its causes and continue to improve their models. But the for today the warming pause should make us pause for thought before taking drastic action. The standard of proof required for public policy must be higher than that for academic study. The unexpected nature of the pause (appearing in the literature only after its appearance in the data), suggests that climate science models might not yet provide a reasonable basis for large-scale public policy action.

(5) A common reaction to the pause from non-scientists

But we see something far different from the chorus of the lay global warming cheerleaders. For example, the comments to these posts, and others mentioning this subject, are largely demonstrations of the first rule of warmistas:

Scientists are authorities, until they challenge global warming dogma. They they’re clowns and charlatans.

Warmistas tend to avoid real science like vampires do holy water. This is the Left’s equivalent to the anti-rationalism that has come to dominate the far Right, both of which prime components of America’s broken Observation-Orientation-Decision-Action loop. We cannot see the world clearly through our thick ideological filters. So our responses don’t work.

Please post your solutions to this in the comments.

(6)  Other Posts about the “pause”

(7) For More Information

Posts describing new science research, and statements by scientists:

  1. An important new article about climate change, 29 December 2008 – Solar influences on Earth’s climate
  2. Richard Feynmann, one of the 20th centuries greatest scientists, talks to us about climate science, 12 February 2009
  3. Big news from NASA about the causes of climate change!, 6 June 2009 — About solar effects
  4. What can climate scientists tell about the drivers of future warming?, 6 February 2012
  5. What can climate scientists tell us about the drivers of future warming? – part two of two, 10 February 2012
  6. The slow solar cycle is getting a lot of attention. What are its effect on us?, 11 February 2012
  7. A famous scientists makes a startling admission about Earth’s climate, 26 April 2012
  8. A look at the debate among climate scientists about global warming, 31 July 2012



19 thoughts on “The IPCC sees the pause in global warming!”

  1. Hmmm. Looked at the report. The coldest year in the twentyfirst century (air temperatures) was warmer than the warmest year in the eighties (which was a year at the end of the eighties). About the same for sea surface temperature.

    1. merijnkibbe,

      Quite right. If you pause when climbing stairs, you’ll find yourself higher than you were before.

      Also, it’s not a steep stairway. Global temperature has risen roughly 1.4 degrees C since 1950 (per the BEST analysis). Most estimates attribute 50-75% of that to anthropogenic causes The leaked IPCC AR5 reports says:

      “It is extremely likely [“>95% probability”] that human activities have caused more than half of the observed increase in global average surface temperature since the 1950s.”

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  4. Anyone can sign up to review the IPCC draft report. That such a reviewer claims to have leaked it speaks volumes.

    1. Yonatan,

      As you note, the only requirement to be an “IPCC expert reviewer” is signing an agreement to keep it confidential. Like so much of the IPCC’s process, the status of “expert reviewer” is meaningless. You get to see the draft.

      But what “volumes” does it speak? There is a long tradition in America of whistleblowing, releasing material that the powerful wish to keep secret.

      That applies to the IPCC procedure, which is to release the policy document — and only much later the actual science upon which it’s supposedly based. That gets the policy recommendations publicity without the appropriate review. Breaking that box seems to me a public service.

  5. The population of Earth went from less than three billions in the 1950 to over seven billions in 2012. Is it really just “extremely likely, 95% probability” that population contributed to the observed increase of temperatures? Close to triple population increase also means that close to tripling polution and heat released to the atmosphere. Controlling population growth probably would slow down global warming more than anything else.

    Yes, there’s more to climate change than population increase, I am aware of that…

    1. That is what the IPCC says. I assume that they have a adequate basis in research for statements about the past.

      I very much doubt you and I are going to develop better analysis with the resources at our use.

    2. When I was a kid back in the 1960′s and 70′s the UN said that we’d have 20 billion people by the year 2000. That was unacceptable, if we didn’t do something about it there would be famines, war and death. We came in around 6.5 billion and today we are at 7 billion. They are still saying that 7 billion is unacceptable and if we don’t do something about it there will be famines, war and death. I’ve been hearing this same thing for 40 years now.

      I think if we had 3 billion they would still say it was too high. More famine, wars and death.

      I think for these people, population scare is the gift that just keeps on giving.

      Ever notice that they always say the population is too high but they never say what a safe population number might be.

      If back then 20 billion was too high and today 7 billion is still too high, what is the right number?

      1. Klem,

        (1) Forecasts of population made in the 1960s and 1970s.

        I cannot find the UN forecasts for maximum population, made since the 1950s, before the 1998 forecast. Demographers explain that forecasts beyond 30 years are unreliable, just extrapolations of current trends. We cannot predict future changes in fertility and new medical technology — let alone wars and plagues.

        (2) What is a sustainable population?

        There are as many opinions as there are experts making the prediction, since there are so many variables. It’s clear that with our current level of technology the world cannot support 7 billion people at American’s standard of living. But with radically new technology? Who can say?

        Imagine a world with ample clean energy, with industrial chemical processes run using catalytic engineering as do our bodies. For those, our descendents, pollution might be a strange word learned in history class. Perhaps like “slavery” and “war”.

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  7. In a posting about possible future energy technologies ( I replied on August 19th 2012 “Try to make a best bet among them. However, don’t count on them.”

    In this case I want to warn in a similar fashion. Don’t count on a temporary bit of luck when the climate (on a decadal scale! – There are good reasons to use the 30 year average approach) doesn’t warm quite as quickly as the models show.

    There are several subjects in which the IPCC report erred in an opposite direction. The minimum Arctic ice cover (half way September) is lower than any of the models in the 4th IPCC report. What could be the consequences isn’t clear yet.
    However: A decrease in temperature contrasts – especially in the summer half year – along the polar front decreases the strength of the polar Jet Stream. This could result e.g. in less violent tornadoes in the US – which is nice (spring 2011 was very probably a relatively rare extreme event) – but also in a bigger chance of blocking anti-cyclones resulting in scourching hot and dry summers severely decreasing the corn yields in the mid-western states of the US.

    Another wild card is the fate of permafrost soils in Canada and Russia/Siberia. Where the tipping point towards a positive feedback of permafrost decomposition (evolution of CO2 and methane), enhancing further warming, lies is currently unknown. But it is there.

    So: Don’t count on our luck too long. By the way: The subject of energy provision, switching to a much more sustainable mix, points in a similar direction. And remember: Rebuilding the energy infrastructure to a much more sustainable set-up is a momentous task which will take many decades (at least ½ a century) anyway.

    To summarize: No reason to panic. But on the other hand: Let’s get started.

    Mazzel & broge / kind regards, Evert Wesker

    1. Wesker,

      (1) I fully agree with respect to new energy tech. It’s essential, IMO, that we rapidly and aggressively fund R&D, but shouldn’t expect anything radical in the next decade. And new tech takes decades to develop and rollout on a large scale.

      (2) I don’t believe we should count on “luck” with respect to any of the the environmental threats. However, I believe that we need to evaluate them all, and wisely allocate available resources. Instead we appear to focus on those with the best grip on the news media.

      There are certain and immediate threats that are largely ignored: habitat destruction (including devastation of the world’s fisheries), resource depletion, and chemical pollution. Theoretical risks, such as massive temperature increases and accelerating sea level rise, must be evaluated in terms of their likelihood and probable magnitude (ie, curve of odds and magnitude) — which is not being well done today (although the IPCC tries) largely due to insufficient funding.

      (3) I am uninterested in the cottage industry of non-scientists saying where the IPCC is wrong. It’s a mystery to me why anyone reads such stuff.

      Most of the allegations that the IPCC is “wrong” reflect a gross misunderstanding of how science works. On the cutting edge there are multiple theories and conflicting data (science tends to take place on the edge of available data).

      Most often what people (like Romm) call “wrong” is just research whose conclusions they disagree with — or dislike. These people are chaff in the lay debate, IMO.

      Moncton takes what I believe is the better approach by pointing out threads of research he considers under-weighted or ignored by the IPCC. That focuses attention on the vital aspect of climate science: understanding what’s generally agreed upon (eg, two centuries of warming, large anthropogenic effects since WWII, big role of CO2 among other drivers) — and what’s still debated (in some cases by minorities of the relevant specialists). Examples: causes of past warming (which varies over time), attribution of past weather trends to warming, forecasts of CO2 emissions, warming, and its effects.

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  9. Analysis by Judith Curry of recent articles in the newspapers about the pause in global warming: “‘Pause’ : Waving the Italian Flag“, 17 October 2012 — “The recent articles in the Daily Mail and the Guardian are generating heated reactions – more heat than light. Lets break down the arguments on both side and assess them systematically.”

  10. Global Temperature Update Through 2012“, James Hansen, M. Sato, R. Ruedy, 15 January 2013 — Opening:

    Global surface temperature in 2012 was +0.56°C (1°F) warmer than the 1951-1980 base period average, despite much of the year being affected by a strong La Nina.
    Global temperature thus continues at a high level that is sufficient to cause a substantial increase in the frequency of extreme warm anomalies. The 5-year mean global temperature has been flat for a decade, which we interpret as a combination of natural variability and a slowdown in the growth rate of the net climate forcing.

    An update through 2012 of our global analysis reveals 2012 as having practically the same temperature as 2011, significantly lower than the maximum reached in 2010. These short-term global fluctuations are associated principally with natural oscillations of tropical Pacific sea surface temperatures summarized in the Nino index in the lower part of the figure. 2012 is nominally the 9th warmest year, but it is indistinguishable in rank with several other years, as shown by the error estimate for comparing nearby years. Note that the 10 warmest years in the record all occurred since 1998.

    The long-term warming trend, including continual warming since the mid-1970s, has been conclusively associated with the predominant global climate forcing, human-made greenhouse gases, which began to grow substantially early in the 20th century. The approximate stand-still of global temperature during 1940-1975 is generally attributed to an approximate balance of aerosol cooling and greenhouse gas warming during a period of rapid growth of fossil fuel use with little control on particulate air pollution, but satisfactory quantitative interpretation has been impossible because of the absence of adequate aerosol measurements.

    Below we discuss the contributions to temperature change in the past decade from stochastic (unforced) climate variability and from climate forcings.

  11. What to Make of a Warming Plateau“, New York Times, 10 June 2013 — Opening:

    As unlikely as this may sound, we have lucked out in recent years when it comes to global warming.

    The rise in the surface temperature of earth has been markedly slower over the last 15 years than in the 20 years before that. And that lull in warming has occurred even as greenhouse gases have accumulated in the atmosphere at a record pace.

    The slowdown is a bit of a mystery to climate scientists. True, the basic theory that predicts a warming of the planet in response to human emissions does not suggest that warming should be smooth and continuous. To the contrary, in a climate system still dominated by natural variability, there is every reason to think the warming will proceed in fits and starts.

    But given how much is riding on the scientific forecast, the practitioners of climate science would like to understand exactly what is going on. They admit that they do not, even though some potential mechanisms of the slowdown have been suggested. The situation highlights important gaps in our knowledge of the climate system, some of which cannot be closed until we get better measurements from high in space and from deep in the ocean.

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