The most recent twist on the “global warming has stopped” meme is the citation of highly respected researchers in support of that incorrect, yet somehow persistent proposition. Once again, the charge is being led by leading climate contrarian Patrick Michaels, ably assisted by Paul “Chip” Knappenberger.
Earlier this year, Michaels’ World Climate Report cited two papers (Easterling and Wehner, 2009 and Solomon et al 2010) as demonstration of mainstream acknowledgment that there has been “no warming whatsoever over the past decade”.
But a closer examination shows that Solomon et al were actually citing the earlier Easterling and Wehner, a paper itself deeply critical of skeptic “cherrypicking” of short-term trend start points. Even worse, discussion of these two papers at World Climate Report contains some of the most egregious examples of quote mining and distortions of others’ work I have ever seen.
To be sure, Solomon et al do acknowledge that warming in the 2000s has been less than projected by the IPCC model ensemble and shows flattening relative to the previous decade (hardly controversial propositions). But their analysis of smoothed observations and decadal model projections implicitly rejects the contrarian obsession with short-term trends, and points the way towards a more compelling characterization and comparative analysis of model projections and observations.
World Climate Report (hereafter WCR) does not provide author information. However, most recent cited articles (for example, at the Cato Institute) give WCR chief editor Patrick Michaels and WCR administrator Paul “Chip” Knappenberger as joint authors. Moreover the blog post in question, What’s Happened to Global Warming, is completely consistent with Knappenberger’s repeated claim that “global warming has stopped”, made recently at the Heartland Institute conference and elsewhere. So until otherwise advised, it’s reasonable to attribute the article to the pair. (It’s also worth noting the ties of these authors and World Climate Report to interests implacably opposed to the regulation of greenhouse gases, as documented at the SourceWatch links given above).
So, without further ado, here are Michaels and Knappenberger on Easterling and Whener’s Is the Climate Warming or Cooling (Geophysical Research Letters, 2010)?
Easterling and Wehner begin their piece noting that “Anthropogenic climate change is one of the most contentious scientific issues of our time. Not surprisingly the issue has generated numerous blogs and websites with a wide range of views on the subject. According to a number of these sources the climate is no longer warming, in fact, some claim the planet has been “cooling’’ since 1998”. They immediately admit that “It is true that if we fit a linear trend line to the annual global land-ocean surface air temperature” “for the period 1998 to 2008 there is no real trend”. Correct – the satellite-based, balloon-based, and thermometer-based global temperature records show no warming whatsoever over the past decade. Claims that the Earth’s temperature is rising at an unprecedented rate are clearly false – nothing could be further from reality. [Emphasis added]
Now let’s look again at that last quote from Easterling and Wehner, but this time with the rest of the paragraph that Michaels and Knappenberger don’t want you to see:
It is true that if we fit a linear trend line to the annual global land-ocean surface air temperature … for the period 1998 to 2008 there is no real trend, even though global temperatures remain well above the long-term average. The unusually strong 1997–1998 El Nino contributed to unusual warmth in the global temperature for 1998 at the start of this period resulting in only a small, statistically insignificant positive trend. However, if we fit a trend line to the same annual global land-ocean temperatures for the 1977–1985 period or the 1981–1989 period we also get no trend, even though these periods are embedded in the 1975–2008 period showing a substantial overall warming. Furthermore, if we drop 1998 and fit the trend to the period 1999–2008 we indeed get a strong, statistically significant positive trend. It is easy to ‘‘cherry pick’’ a period to reinforce a point of view … [Emphasis added]
The trends for 2000-2009 are also positive in all three surface data series. So even if one accepts the short-term linear trend as an appropriate metric, the claim that “thermometer-based global temperature records show no warming whatsoever over the past decade” is an outrageous lie. No more, no less.
Next up is the February 2010 Science article from Solomon et al, Contributions of Stratospheric Water Vapor to Decadal Changes in the Rate of Global Warming. Michaels and Knappenberger gleefully quote the opening paragraph:
…. However, the trend in global surface temperatures has been nearly flat since the late 1990s despite continuing increases in the forcing due to the sum of the well-mixed greenhouse gases (CO2, CH4, halocarbons, and N2O), raising questions regarding the understanding of forced climate change, its drivers, the parameters that define natural internal variability, and how fully these terms are represented in climate models. [Emphasis added]
Michaels and Knappenberger comment:
Admitting that the trend in global temperatures has been flat over the past decade will not win any awards for this team, so we once again applaud their honesty. [Emphasis added]
Notice that “nearly flat” is now simply “flat”. They might as well have replaced “nearly” with an ellipsis “…”. That would have been so much simpler.
And, once again, Michaels and Knappenberger exploit confusion about exactly which period (which “past decade”) is being discussed.
But it gets better. For there is the niggling matter of the citation for this sentence from Solomon et al, which turns out to be – wait for it – Easterling and Wehner! But, as we have already seen, that paper points out that the trend “since the late nineties” depends very much on the selection of the start year. 1998-2008 gives a range of linear trend from 0.11C/decade (NASA-GISS) down to 0.02C/decade (HadCRUT). But if one starts in 1999, NASA-GISS jumps to 0.19C/decade, while HadCRUT is at 0.11C/decade.
So it’s even somewhat debatable whether this set of linear trends should be called “nearly flat” since the “late nineties”. But what is not debatable is the dishonesty of Michaels and Knappenberger in citing Solomon et al as further support for the mendacious claim that surface temperatures have been categorically “flat” and that there has been “no warming whatsoever over the past decade”.
That’s especially true when one considers the actual numbers. 2000-2009 saw linear trends of 0.12C/decade in NASA-GISS and 0.05C/decade in HadCRUT. But that’s only part of the story. If one looks at decadal change in 2000-2009 relative to the previous period, both NOAA and HadCRUT were an average of 0.17C above the 90s, while NASA-GISS was a full 0.2C higher.
Not that the contrarian obsession with short term linear trends figure much in Solomon et al; rather, they present a smoothed average of all three surface temperature data sets.
Although the citation of mainstream science research in support of these bogus claims is a recent phenomenon, the claims themselves are not new. As summarized at SourceWatch, Michaels and Knappenberger had a previous go at this last year:
In March 2009, Michaels, under the auspices of the Cato Institute, circulated a draft advertisement that stated: “Surface temperature changes over the past century have been episodic and modest and there has been no net global warming for over a decade now … The computer models forecasting rapid temperature change abjectly fail to explain recent climate behavior.” [Link] The ad statements were analyzed and criticized in detail at the RealClimate blog. [Link]
In support of the statements, Chip Knappenberger of World Climate Report referred readers to recent testimony by Michaels to the House of Representatives Energy and Environment sub-committee. [Link] That too was responded to at length by Gavin Schmidt of RealClimate.org [Link]
The recent submission to Geophysical Research Letters of research by Michaels, Knappenberger and four others (including the surprise addition of James Annan) is bringing new attention to model-observation comparisons based on short-term linear trends. (Knappenberger’s controversial Heartland conference presentation can be viewed at the conference website [PPT presentation and video]).
There are two contextual aspects that should be discussed in assessing this initiative, which seeks to endow short-term trend analysis with some respectability.
First, it should be noted that up until recently short-term trends were rarely discussed in actual published climate science; in fact, the IPCC Fourth Assessment Report goes out of its way to eschew such discussion, preferring to present projections in terms of decadal or longer averages. For example, the medium term projection to 2030 are given in terms of a twenty-year average (2011 to 2030) relative to a twenty-year baseline (1980-1999).
James Annan has noted that the Michaels et al analysis is in line with the approach of Easterling and Wehman, not to mention that of Gavin Schmidt at RealClimate. But these initiatives were meant to rebut the overreaching claims in the blogosphere, as noted above, not as indicators of the way to the most compelling analysis. They should certainly not be cited in support of the view that much can be concluded from a linear fit analysis of ten years of observational data.
But surely if the attempt is to be made to draw inferences from such short periods, there are other ways than simply looking at a ten-year (or even shorter) trend line. An obvious flaw in such an analysis is that it ignores any consideration of the temperature record previous to the period being analyzed. A glance at the following table of various linear trends (in deg C per decade) shows why this may give misleading results:
|1990 – 1999||0.181||0.228||0.244|
|2000 – 2009||0.122||0.068||0.054|
|1990 – 2009||0.188||0.167||0.167|
| 2000s avg. increase
Clearly, there has been some “flattening” in the 2000s even if the assertion of “no warming whatsoever” is exposed for the canard that it is. But it’s equally clear that there are seeming contradictions in the data. GISS actually shows a slightly higher trend over the two decades than for the 1990-99 decade-long trend. HadCRUT’s low (but still positive trend) in the 2000s is somewhat contradicted by a more moderate reduction in the two-decade trend to 2009. And as already noted, the fact that all three series show significant increases in the 2000s relative to the 1990s should also give pause.
I’ll be returning to the implications of such considerations, and alternative analyses of decadal change, in subsequent posts. In the mean time, here is last year’s initial tentative effort at an approach using smoothing and decadal averages. The treatment acknowledges that recent temperatures have been below projections, and at the same time avoids the miasma of interpreting rapidly fluctuating short-term trends.
At that time, I wrote:
So for 2000-2008, the IPCC smoothed projection was an average of 0.33 deg +/- 0.13 deg (90% confidence interval) above the 1980-99 baseline. Both NASA GISS (0.26 deg) and HADCrut (o.25 deg) were within that range, albeit in the lower part.
It should be noted that the stated confidence interval seems fine for the smoothed observation curves, but probably understates the interval for the decadal average. But the approach seems a promising one to explore – namely develop as a test statistic the average over a period of interest (in this case, the convenient decadal projection period 2000-2009), expressed as an increase relative to the immediately preceding baseline period.
But there is a second, more disturbing, element in all of this. In his recent presentation at the Heartland climate conference and elsewhere, Paul Knappenberger repeatedly stretched his conclusions way beyond what could be reasonably inferred or interpreted from the actual analysis (and, yes, I will go into this in detail in a future post). And the categorical World Climate Report claim that there has been no warming “whatsoever” is a clear falsehood.
That yawning gap between informal commentary and published research (whether one’s own or of others) is one of the defining hallmarks of “skeptical” climate science. That’s disgraceful enough, but it also indicates a possible willingness to stretch beyond acceptable limits even within the published research itself.
Consider the following early paper by Michaels and Knappenberger, along with Robert Balling and Robert Davis. Observed warming in cold anticyclones was published in 2000 in the journal Climate Research. (This was only one of many dubious articles edited by Chris de Freitas, whose tenure eventually resulted in the mass resignation of half the journal’s editors in 2004).
As noted in the abstract:
On a seasonally weighted basis, a relatively small area (12.8%) contributed over half of the annual warming, and in the winter 26% of the area accounts for 78% of the warming. Our analysis demonstrates that this warming is almost exclusively confined to the dry, cold, anticyclones of Siberia and northwestern North America.
However, the conclusion goes well beyond anything reasonably supported by the analysis, and even invokes the meme of beneficial global warming:
Strong warming that is confined mainly to the Siberian and Canadian winter has a much different effect on society than a similarly large heating in mid-latitude urban and agricultural areas during the summer. To us, this pattern of temperature change seems a logical ‘discernible human influence’ on the climate when the interplay between greenhouse changes and moisture content is considered. Warming of this air mass type may, in fact, be benign or even beneficial, although the final valuation of global warming remains elusive.
So there is every reason to suppose that the latest Michaels et al submission may contain similarly exaggerated material in its background or conclusion. The refusal by Michaels and Knappenberger, at least so far, to release a draft of the submitted article (not even the abstract) does little to quell such doubts.
While we’re waiting, there will be plenty of other Michaels material to ponder, including his ravings at the Heartland conference. And I’ll also be posting a complete set of abstracts and links for nine of Michaels’ articles at Climate Research (all but one edited by Chris de Freitas). The above quote is just the tip of the iceberg, unfortunately.