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What Does the Last Decade Tell Us about Global Warming? (Hint: the ‘skeptics’ have the momentum)

By Chip Knappenberger -- September 28, 2009

“Worldwide temperatures haven’t risen much in the past decade…. If you are a climate-change activist pointing to year after year of mounting climate crises, you might want to rethink your approach.”

- Richard Kerr, Science, May 2, 2008.

There has been a flurry of activity in recent weeks in the discussion as to the significance (scientific, political, social) of the evolution of the global average surface temperature during the past 10 years or so.

For those of you who don’t know, the surface temperature of the globe, as a whole, has not warmed-up by anyone’s calculation since at least the turn of the century (January 2001) and depending on your dataset and statistical technique of choice, perhaps as far back as January 1997. And all of this non-warming occurred over a period of time during which the global emissions of CO2 increased faster than ever before (thanks primarily to China). In fact, anthropogenic greenhouse-gas forcing is about 5 percent greater now than a decade ago (about 16 parts per million).

To many folks who have, for years, been fed a constant course of “the-world-is-heating-up-faster-than-ever-before-and-you-are-the-cause,” 9 to 12 years of no warming at all seems to indicate that something is amiss with this mantra.

This was reflected in a Gallup Poll last spring, which found the highest percentage yet of people who think that “global warming” is being “exaggerated.” And this number has been growing.

IPCC “Consensus” and Unwarming

The growth in climate realism (i.e., a realization that alarmists are overplaying the probable impact of CO2 emissions) has most certainly been sparked by the fact that the rate of the earth’s temperature rise has been slowing rather than accelerating, contrary to general IPCC conclusions. This development, naturally, plays into the political debate about (at the 11th hour if not midnight) “mitigating” potential climate change through carbon dioxide emissions reductions.

While the mainstream press has been slow to embrace the fact that the earth’s temperature rise has ground to a halt, Andy Revkin’s recent article in the New York Times has (belatedly [correction: see comments below]) brought the issue the issue front and center.  Already, there had been lively discussions on this subject in the halls of Congress and all across of the web.

For instance, this past winter, the recent lack of warming was a focal point in testimony given by Dr. Patrick Michaels before the House Subcommittee on Energy and Environment.

More recently, this fact was included by Matt Rogers writing for the popular “Capital Weather Gang” blog as among his list of 10 reasons for his “Skeptical Take on Global Warming.”

And the Houston Chronicle’s Eric Berger made a pretty big deal about it in his recent SciGuy blog post, stating “But a funny thing happened on the way to the end of the world: hurricane activity on the global scale is near historical lows. And the Earth seems to have, at least temporarily, stopped warming” (emphasis added).

But the growing popularity of this line of reasoning and it potential to do a lot of public relations damage to the alarmist cause is not going unnoticed, whether at Climate Progress or other ‘alarmist’ bastions.

Pew Center Tries to Quiet Science Concern

In its recent update of its global-warming science material, the Pew Center included a list of climate “misconceptions.” Among them was this one:

The Misconception:

The last few years have been cooler, so global warming can’t be real;
Or, Global warming stopped in 1998;
Or, The world has been cooling for the past decade.

Pew reported that “The Reality” was:

The climate is defined by long-term averages in global temperature and other climate metrics, and those are still increasing.

This response basically avoided taking the original contention head-on.

In fact, global warming has stopped.

The question, thus, needs to be: “Since the average global surface temperature has remained relatively unchanged for the past decade or so, what does this mean for our understanding of what drives temperature changes, and what we may expect in the future?”

The answer to this question could be that there is something wrong with our scientific understanding of what makes the climate tick—or at least how this understanding is translated into the computer code of climate models—which of course would have all sorts of implications.

So, instead of going there, the primary effort to-date has been to try to demonstrate that there actually is no problem at all—that this lack of temperature rise is just what you would expect to occur with “global warming,” to go along with other expectations such as increasing sea ice in the Southern Ocean, increased ice accumulation across Antarctica (or should that be decreasing ice accumulation across Antarctica—I guess it all depends on what the latest study shows), more precipitation (or less depending on which is currently making the news), more hurricanes (well, not more in number, but more intense, or if not more intense, then they’ll be bigger in areal extent, or maybe…), cold outbreaks (when they occur, warm outbreaks otherwise), etc.

New Lines of ‘Skeptic’ Research

The first paper in the scientific literature to tackle the issue of just how long a period of no warming should be expected was published a few months ago by David Easterling and Michael Wehner. They showed that a zero or negative trend of a decade in length should occur (according to climate models) about 10% of the time during the first half of the 21st century. Another paper appeared a couple of weeks ago, led by Jeffrey Knight, which also concluded that, according to climate models, a negative (or zero) 10-yr trend should be expected to occur about 10% of the time, and further, that a negative trend couldn’t be statistically ruled out as improbable until after about a 15-yr period.

But, these two studies are not the end all and be all on the topic. They both, to a certain degree, include sources of variability besides just intramodel “natural” variability when determining the distribution of the modeled temperature trends. This intermixing of various noise sources has the probable effect of enhancing the perceived degree of “climate” variability and thus making low trends seem more common they should be.

My colleagues and I are currently working up a few tests of our own to see just how common our current period of no global warming really is—at least from the standpoint of today’s climate models when run with projected changes in anthropogenic emissions (greenhouse gases and aerosols). Our results are indicating that 10-yr periods of no warming are much more infrequent in climate model projections than indicated by either Easterling and Wehner (2009) or Knight et al (2009). Hopefully, our results will make it into the scientific literature at some point in the near future and provide additional information to the debate.

But, regardless of the specific details, everyone who looks at it is finding something generally similar, that is, the current lack of warming is bumping against model expectations for the longest period of time over which natural variations could offset the warming pressure from increasing greenhouse gases.

The longer the lack of warming continues the more evidence builds that climate models don’t have a good handle on the situation of how the earth’s climate behaves—which erodes their usefulness as reliable indicators of future climate.

Climate modelers and other climate change (and emission regulation) hopefuls have been looking to the tropical Pacific for signs of the appearance of a strong El Niño to help right the ship and restart things on their warming way (El Niños tend to produce a rise in the earth’s average surface temperature), but the jury is still out as to what to expect from the developing situation there—there are indications that an El Niño is brewing, but just how strong it may become (and how much it will elevate global temperatures) is still a much debated topic (forecasting El Niño strength is notoriously unreliable).

El Niño?

But even a strong El Niño won’t quell the realists’ attack, for El Niños are temporary events and are typically followed by a couple years of cooler temperatures as La Niña conditions often move in to take their place. So, what everyone will be waiting for (if a big El Niño does develop) will be to see whether post-El Niño temperature settle down to pre-event values, or whether they remain relatively elevated. We won’t know this for at least several more years.

So the issue of a sluggishly warming world and what it means is going to be with us for a long time (several years at the very least), and some studies such as Keenlyside et al. (2008) and Swanson and Tsonis (2009) indicate that it will much longer than that. (Lindzen and Choi [2009] think it will be with us forever.) Its ultimate impact on climate science (and climate/energy policy) will hinge on whether or not (and if so, how severely) our understanding of climate processes will have to be altered in order to explain why it happened.

In the meantime, while all this is being sorted out, here is some good advice, meted out last year by Science magazine writer Richard Kerr:

Worldwide temperatures haven’t risen much in the past decade…. If you are a climate-change activist pointing to year after year of mounting climate crises, you might want to rethink your approach.


Easterling, D.R., Wehner, M. F., 2009. Is the climate warming or cooling? Geophysical Research Letters, 36, L08706, doi:10.1029/2009GL037810.

Keenlyside, N.S., et al., 2008. Advancing decadal-scale climate prediction in the North Atlantic sector. Nature, 453,84-88.

Kerr, Richard. “Mother Nature Cools the Greenhouse, But Hotter Times Still Lie Ahead,” Science, May 2, 2008, p. 595.

Knight, J., et al., 2009. Do global temperature trends over the last decade falsify climate predictions? In: Peterson, T. C., and M. O. Baringer (eds), “State of the Climate in 2008” Special Supplement to the Bulletin of the American Meteorological Society, 90.

Lindzen, R.S., and Y-S., Choi, 2009. On the determination of climate feedbacks from ERBE data. Geophysical Research Letters, 36, L16705, doi:10.1029/2009GL039628.

Swanson, K. L., and A. A. Tsonis, 2009. Has the climate recently shifted? Geophysical Research Letters, 36,L06711, doi:10.1029/2008GL037022.


  1. The sceptics have momentum « Green Grift  

    […] change, media bias Leave a Comment  The chicken littles and their MSM friends are in denial. For those of you who don’t know, the surface temperature of the globe, as a whole, has not warmed-up by anyone’s calculation […]


  2. Klem  

    Relax, over the last 10 years temperatures have remained level or have dropped a bit. All the climate scientists need to do is go back over the data and ‘recalibrate’ their equipment. If you read many of their studies, they often do this when the data does not support their claims. It’s an easy solution that works every time.


  3. cknappenberger  

    Andy Revkin kindly emailed me to (correctly) point out, that he has not, in fact, been “belated” in covering the issue of the recent behavior of global temperatures.

    Links to some of his previous pieces touching on the topic can be found here, here, and here.



  4. Andrew  

    If we take the Hadley Data (despite it’s lack of documentation…) From the last 144 months (September 1997 to August 2009) the trend is:

    ~ -.014 Degrees per decade.

    It appears to me that, since this result also holds for the satellite data (I’ve done the calculations several times) No warming for a full twelve years is a solid conclusion.


  5. Global warming trends - not what you may think - Orange Punch - OCRegister.com  

    […] is about 5 percent greater now than a decade ago (about 16 parts per million).” – Chip Knappenberger, 20 years of experience as a climate researcher, including with the Virginia State Climatology […]


  6. Noblesse Oblige  

    Yes.. But.
    1. Cognitive dissonance is making the advocates claims ever more outlandish and ever more shrill.
    2. Data manipulation and outright fraud is increasing in an effort to cover up the real science. (See for example the developments over the last few days on the infamous hockey stick scam).
    2. The EU and US seem intent on exerting control over the energy industry, and therefore their economies as a whole, as part of their political agenda. The state of the science doesn’t matter. They will just make it up. Just listen to the Holdren’s outright falsehoods, as expressed by Obama.


  7. Is 350 the New 450? | OpenMarket.org  

    […] although CO2 concentrations have increased at an accelerating rate, global temperatures have been stagnant or even declined slightely. To my knowledge, no scientist in the late 1990s predicted a roughly 10-year period of no warming […]


  8. Jaroslaw Sobieski  

    To add to the point of your article, I would like to bring to your attention some information that you may or may not be familiar with.

    The NASA Langley Research Center where I work designed and operated an Earth Radiation Budget satellite program (ERB) in the 90’s. The purpose was to determine whether the amount of energy absorbed by the Planet Earth from outside is equal to, smaller than, or greater than that radiated back into space. Obviously, that energy balance is profoundly important to know whether the Earth is in a thermal steady state, cools down, or warms up.

    The program has concluded (there were and still are other satellites , e.g., the CERES series, that followed up) and the results were archived at the NASA Goddard Space Center. They are summarized on a number of websites and cited in many articles (references are available). The principal websites are




    (The larc website is the root reference)

    The key result was surprising: the energy received equals to that radiated out; all three websites provide data to show that. It is surprising because this equilibrium would indicate the Earth temperature not changing despite that the ground data indicate warming (regardless whether people are guilty or not). Elementary thermodynamics tells us this.

    However, the ground data do show warming. How such warming is possible despite the Earth radiative energy balance? One explanation that I can think of is that there may be a slight imbalance with the energy absorbed exceeding that radiated out by a small amount below the satellite instrumentation resolution. If so, the imbalance is small and not a reason for the doomsday alarm trumpeting by Mr. Gore and his media sycophants.

    The other possibility is that the energy is in balance but is being redistributed within the Earth oceans and atmosphere. If the latter were true, we should see mutually offsetting warming and cooling in various regions of the globe. If the redistribution is responsible for the ground data indicating that the climate is changing, then we do not have global warming or cooling, the whole process is a resultant of regional variations, and the research now preoccupied with CO2 ought to be redirected to the causes and effects of such redistribution. A very different issue.

    I thought that it might be an opportunity for students of the subject like you to look deeper into the ERB data and their interpretation. Perhaps, it would be a very constructive contribution to the climate changing debate. It is very puzzling indeed that the data available on the Earth energy balance (collected by the US Government at a considerable taxpayer expense) are not being mentioned as the key piece of information in that debate. It is just a single number but so very important. Maybe it is being ignored because it does not support the cause for alarm, apparently so dear to many people.


    Jaroslaw Sobieski, PhD, AIAA Fellow.


  9. Craig Goodrich  

    Another point — adding to Dr Sobieski — is that the normal El Niño oscillation stores enormous amounts of heat in the Pacific Warm Pool at depths below 200 meters, then spreads it over the surface where it effects climate during an El Niño event. Thus incoming and outgoing radiation may balance in a longer term but not short-term.

    Yet another consideration is that the entire CO2-driven Global Warming theory, as expressed in the silly models, has proven completely, spectacularly wrong in every concrete prediction it has made — no extra warming in the lower troposphere, no ocean heat buildup during the current cool spell, and so on. Its only confirmation is a weak correlation between temperature and CO2 concentration for the years 1980–1997.

    By contrast, a competing theory — the Svensmark effect, solar variation affecting cosmic rays — has good correlations on time scales from months to millions of years.

    The IPCC models are, as some of us have been saying for twenty years, useless simpleminded trash. And when the American (and European) people realize this, and look at the enormous price they have already paid for this nonsense, some scientists and many politicians may find themselves lynched from their own beloved wind turbines.


  10. Bob R Geologist  

    No surprises here other than the statement that negated any warming by CO2 whatever. When the Kyoto protocols first came out, I knew from our knowledge of past climates that concentrations of CO2 more than 10 times our present 380ppm, never caused climate overheating detrimental to plant and animal life. Why all the alarm at the prospect of merely doubling it? The answer can only be that there is big, big money to be made our of climate warming hysteria!! The proponents are not ranting idiots, just venal profiteers and scientists prostituting their disciplines and power seeking politicians. This has become a scandal of world wide proportions. And, worst of all, our media has been corrupted. I have had a dozen fact laden letters and opinion pieces rejected by my newspaper. The past 10 years that the climate has not warmed has cracked the foundation of this monsterous scam but it will require at least another cool 10 years to kill the beast. The wreckage will be world wide. I just hope our once great country will not be a part of it.


  11. MarkB  

    Regarding those three Andy Revkin articles. The second is merely a note, announcing the first. The first seeks to explain away the current conditions, with the typical “now that it’s happened, we knew it all along” talk from the same scientists who have given us apocalyptic talk up to now. The third really isn’t on topic – it discusses the public’s apathy to said apocalyptic predictions. Andy’s attempts at even-handedness have been consistant – “someone says (one paragraph), but all these scientists disagree (rest of article).”

    Andy Revkin has made a career on reporting Global Warming, not covering the debate. He’s all in, and he needs to protect his chips.


  12. Willem Post  

    This article says there has been warming in the past 12 years.



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