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Drought and Global Climate Change: An Analysis of Statements by Roger Pielke Jr

Posted on 1 March 2014 by Guest Author

This is a re-post from by Presidential Science Advisor John Holdren


In the question and answer period following my February 25 testimony on the Administration’s Climate Action Plan before the Oversight Subcommittee of the U.S. Senate’s Committee on Environment and Public Works, Senator Jeff Sessions (R-AL) suggested that I had misled the American people with comments I made to reporters on February 13, linking recent severe droughts in the American West to global climate change. To support this proposition, Senator Sessions quoted from testimony before the Environment and Public Works Committee the previous July by Dr. Roger Pielke, Jr., a University of Colorado political scientist. Specifically, the Senator read the following passages from Dr. Pielke’s written testimony:

It is misleading, and just plain incorrect, to claim that disasters associated with hurricanes, tornadoes, floods or droughts have increased on climate timescales either in the United States or globally.

Drought has “for the most part, become shorter, less, frequent, and cover a smaller portion of the U.S. over the last century”. Globally, “there has been little change in drought over the past 60 years.”

Footnotes in the testimony attribute the two statements in quotation marks within the second passage to the US Climate Change Science Program’s 2008 report on extremes in North America and a 2012 paper by Sheffield et al. in the journal Nature, respectively. 

I replied that the indicated comments by Dr. Pielke, and similar ones attributed by Senator Sessions to Dr. Roy Spencer of the University of Alabama, were not representative of mainstream views on this topic in the climate-science community; and I promised to provide for the record a more complete response with relevant scientific references.

Dr. Pielke also commented directly, in a number of tweets on February 14 and thereafter, on my February 13 statements to reporters about the California drought, and he elaborated on the tweets for a blog post on The Daily Caller site (also on February 14) [SkS note: Pielke did not author The Daily Caller blog post; they did however embed his Tweets]. In what follows, I will address the relevant statements in those venues, as well. He argued there, specifically, that my statements on drought “directly contradicted scientific reports”, and in support of that assertion, he offered the same statements from his July testimony that were quoted by Senator Sessions (see above). He also added this:

The United Nations Intergovernmental Panel on Climate Change found that there is “not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought.”

In the rest of this response, I will show, first, that the indicated quote from the US Climate Change Science Program (CCSP) about U.S. droughts is missing a crucial adjacent sentence in the CCSP report, which supports my position about drought in the American West. I will also show that Dr. Pielke’s statements about global drought trends, while irrelevant to my comments about drought in California and the Colorado River Basin, are seriously misleading, as well, concerning what is actually in the UN Panel’s latest report and what is in the current scientific literature.

Drought trends in the American West

My comments to reporters on February 13, to which Dr. Pielke referred in his February 14 tweet and to which Senator Sessions referred in the February 25 hearing, were provided just ahead of President Obama’s visit to the drought-stricken California Central Valley and were explicitly about the drought situation in California and elsewhere in the West.

That being so, any reference to the CCSP 2008 report in this context should include not just the sentence highlighted in Dr. Pielke’s testimony but also the sentence that follows immediately in the relevant passage from that document and which relates specifically to the American West.  Here are the two sentences in their entirety (Source):

Similarly, long-term trends (1925-2003) of hydrologic droughts based on model derived soil moisture and runoff show that droughts have, for the most part, become shorter, less frequent, and cover a smaller portion of the U.S. over the last century (Andreadis and Lettenmaier, 2006). The main exception is the Southwest and parts of the interior of the West, where increased temperature has led to rising drought trends (Groisman et al., 2004; Andreadis and Lettenmaier, 2006).

[SkS note: Pielke's testimony did include information about rising drought trend in the Southwestern and Western US, but it was buried in his footnotes]

Linking Drought to Climate Change

In my recent comments about observed and projected increases in drought in the American West, I mentioned four relatively well understood mechanisms by which climate change can play a role in drought. (I have always been careful to note that, scientifically, we cannot say that climate change caused a particular drought, but only that it is expected to increase the frequency, intensity, and duration of drought in some regions ? and that such changes are being observed.)

The four mechanisms are:

  1. In a warming world, a larger fraction of total precipitation falls in downpours, which means a larger fraction is lost to storm runoff (as opposed to being absorbed in soil).
  2. In mountain regions that are warming, as most are, a larger fraction of precipitation falls as rain rather than as snow, which means lower stream flows in spring and summer.
  3. What snowpack there is melts earlier in a warming world, further reducing flows later in the year.
  4. Where temperatures are higher, losses of water from soil and reservoirs due to evaporation are likewise higher than they would otherwise be.

Regarding the first mechanism, the 2013 report of the IPCC’s Working Group I, The Science Basis (page 110), deems it “likely” (probability greater than 66%) that an increase in heavy precipitation events is already detectable in observational records since 1950 for more land areas than not, and that further changes in this direction are “likely over many land areas” in the early 21st century and “very likely over most of the mid-latitude land masses” by the late 21st century.  The second, third, and fourth mechanisms reflect elementary physics and are hardly subject to dispute (but see also additional references provided at the end of this comment).

As I have also noted in recent public comments, additional mechanisms have been identified by which changes in atmospheric circulation patterns that may be a result of global warming could be affecting droughts in the American West. There are some measurements and some analyses suggesting that these mechanisms are operating, but the evidence is less than conclusive, and some respectable analysts attribute the indicated circulation changes to natural variability. The uncertainty about these mechanisms should not be allowed to become a distraction obscuring the more robust understandings about climate change and regional drought summarized above.

Global Drought Patterns

Drought is by nature a regional phenomenon. In a world that is warming on the average, there will be more evaporation and therefore more precipitation; that is, a warming world will also get wetter, on the average. In speaking of global trends in drought, then, the meaningful questions are (a) whether the frequency, intensity, and duration of droughts are changing in most or all of the regions historically prone to drought and (b) whether the total area prone to drought is changing.

Any careful reading of the 2013 IPCC report and other recent scientific literature about on the subject reveals that droughts have been worsening in some regions in recent decades while lessening in other regions, and that the IPCC’s “low confidence” about a global trend relates mainly to the question of total area prone to drought and a lack of sufficient measurements to settle it. Here is the key passage from the Technical Summary from IPCC WGI’s 2013 report (page 112):

Compelling arguments both for and against significant increases in the land area affected by drought and/or dryness since the mid–20th century have resulted in a low confidence assessment of observed and attributable large-scale trends. This is due primarily to a lack and quality of direct observations, dependencies of inferred trends on the index choice, geographical inconsistencies in the trends and difficulties in distinguishing decadal scale variability from long term trends.

The table that accompanies the above passage from the IPCC’s report ? captioned “Extreme weather and climate events: global-scale assessment of recent observed changes, human contribution to the changes, and projected further changes for the early (2016–2035) and late (2081–2100) 21st century” ? has the following entries for “Increases in intensity and/or duration of drought”: under changes observed since 1950, “low confidence on a global scale, likely changes in some regions” [emphasis added]; and under projected changes for the late 21st century, “likely (medium confidence) on a regional to global scale”.

Dr. Pielke’s citation of a 2012 paper from Nature by Sheffield et al., entitled “Little change in global drought over the past 60 years”, is likewise misleading. That paper’s abstract begins as follows:

Drought is expected to increase in frequency and severity in the future as a result of climate change, mainly as a consequence of decreases in regional precipitation but also because of increasing evaporation driven by global warming 1–3. Previous assessments of historic changes in drought over the late twentieth and early twenty-first centuries indicate that this may already be happening globally. In particular, calculations of the Palmer Drought Severity Index (PDSI) show a decrease in moisture globally since the 1970s with a commensurate increase in the area of drought that is attributed, in part, to global warming 4–5.

The paper goes on to argue that the PDSI, which has been relied upon for drought characterization since the 1960s, is too simple a measure and may (the authors’ word) have led to overestimation of global drought trends in previous climate-change assessments ? including the IPCC’s previous (2007) assessment, which found that “More intense and longer droughts have been observed over wider areas since the 1970s, particularly in the tropics and subtropics.”

The authors argue for use of a more complex index of drought, which, however, requires more data and more sophisticated models to apply. Their application of it with the available data shows a smaller global drought trend than calculated using the usual PDSI, but they conclude that better data are needed. The conclusion of the Sheffield et al. paper has proven controversial, with some critics pointing to the inadequacy of existing observations to support the more complex index and others arguing that a more rigorous application of the new approach leads to results similar to those previously obtained using the PDSI.

A measure of the differences of view on the topic is available in a paper entitled “Increasing drought under global warming in observations and models”, published in Nature Climate Change at about the same time as Sheffield et al. by a leading drought expert at the National Center for Climate Research, Dr. Aiguo Dai. Dr. Dai’s abstract begins and ends as follows:

Historical records of precipitation, streamflow, and drought indices all show increased aridity since 1950 over many land areas 1,2. Analyses of model-simulated soil moisture 3,4, drought indices 1,5,6, and precipitation minus evaporation 7 suggest increased risk of drought in the twenty-first century. … I conclude that the observed global aridity changes up to 2010 are consistent with model predictions, which suggest severe and widespread droughts in the next 30–90 years over many land areas resulting from either decreased precipitation and/or increased evaporation.

The disagreement between the Sheffield et al. and Dai camps appears to have been responsible for the IPCC’s downgrading to “low confidence”, in its 2013 report, the assessment of an upward trend in global drought in its 2007 Fourth Assessment and its 2012 Special Report on Extreme Events.

Interestingly, a number of senior parties to the debate ? including Drs. Sheffield and Dai ? have recently collaborated on a co-authored paper, published in the January 2014 issue of Nature Climate Change, entitled “Global warming and changes in drought”. In this new paper, the authors identify the reasons for their previous disagreements; agree on the need for additional data to better separate natural variability from human-caused trends; and agree on the following closing paragraph (quoted here in full):

Changes in the global water cycle in response to the warming over the twenty-first century will not be uniform. The contrast in precipitation between wet and dry regions and between wet and dry seasons will probably increase, although there may be regional exceptions. Climate change is adding heat to the climate system and on land much of that heat goes into drying. A natural drought should therefore set in quicker, become more intense, and may last longer. Droughts may be more extensive as a result. Indeed, human-induced warming effects accumulate on land during periods of drought because the ‘air conditioning effects’ of water are absent. Climate change may not manufacture droughts, but it could exacerbate them and it will probably expand their domain in the subtropical dry zone.

Additional References (with particularly relevant direct quotes in italics)

Christopher R. Schwalm et al., Reduction of carbon uptake during turn of the century drought in western North America, Nature Geoscience, vol. 5, August 2012, pp 551–556.

The severity and incidence of climatic extremes, including drought, have increased as a result of climate warming. … The turn of the century drought in western North America was the most severe drought over the past 800 years, significantly reducing the modest carbon sink normally present in this region. Projections indicate that drought events of this length and severity will be commonplace through the end of the twenty-first century.

Gregory T. Pederson et al., The unusual nature of recent snowpack declines in the North American Cordillera, Science, vol. 333, 15 July 2011, pp 332–335.

Over the past millennium, late 20th century snowpack reductions are almost unprecedented in magnitude across the northern Rocky Mountains and in their north-south synchrony across the cordillera. Both the snowpack declines and their synchrony result from unparalleled springtime warming that is due to positive reinforcement of the anthropogenic warming by decadal variability. The increasing role of warming on large-scale snowpack variability and trends foreshadows fundamental impacts on streamflow and water supplies across the western United States.

Gregory T. Pederson et al., Regional patterns and proximal causes of the recent snowpack decline in the Rocky Mountains, US, Geophysical Research Letters, vol. 40, 16 May 2013, pp 1811–1816.

The post–1980 synchronous snow decline reduced snow cover at low to middle elevations by ~20% and partly explains earlier and reduced streamflow and both longer and more active fire seasons. Climatologies of Rocky Mountain snowpack are shown to be seasonally and regionally complex, with Pacific decadal variability positively reinforcing the anthropogenic warming trend.

Michael Wehner et al., Projections of future drought in the continental United States and Mexico, Journal of Hydrometeorology, vol. 12, December 2011, pp 1359–1377.

All models, regardless of their ability to simulate the base-period drought statistics, project significant future increases in drought frequency, severity, and extent over the course of the 21 st century under the SRES A1B emissions scenario. Using all 19 models, the average state in the last decade of the twenty-first century is projected under the SRES A1B forcing scenario to be conditions currently considered severe drought (PDSI<–3) over much of the continental United States and extreme drought (PDSI<–4) over much of Mexico.

D. R. Cayan et al., Future dryness in the southwest US and the hydrology of the early 21 st century drought, Proceedings of the National Academy of Sciences, vol. 107, December 14, 2010, pp 21271–21276.

Although the recent drought may have significant contributions from natural variability, it is notable that hydrological changes in the region over the last 50 years cannot be fully explained by natural variability, and instead show the signature of anthropogenic climate change.

E. P. Maurer et al., Detection, attribution, and sensitivity of trends toward earlier streamflow in the Sierra Nevada, Journal of Geophysical Research, vol. 112, 2007, doi:10.1029/2006JD08088.

The warming experienced in recent decades has caused measurable shifts toward earlier streamflow timing in California. Under future warming, further shifts in streamflow timing are projected for the rivers draining the western Sierra Nevada, including the four considered in this study. These shifts and their projected increases through the end of the 21st century will have dramatic impacts on California’s managed water system.

H. G. Hidalgo et al., Detection and attribution of streamflow timing changes to climate change in the western United States, Journal of Climate, vol. 22, issue 13, 2009, pp 3838–3855, doi: 10.1175/2009JCLI2740.1.

The advance in streamflow timing in the western United States appears to arise, to some measure, from anthropogenic warming. Thus the observed changes appear to be the early phase of changes expected under climate change. This finding presages grave consequences for the water supply, water management, and ecology of the region. In particular, more winter and spring flooding and drier summers are expected as well as less winter snow (more rain) and earlier snowmelt.

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Comments 1 to 12:

  1. There is a malformed link in the first sentence of the section "Drought trends in the American West".

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  2. Kudos to Dr Holdren for taking the time to address these "seriously misleading" statements by Dr Roger Pielke, Jr. and the Republican Senator from Alabama, Mr Sessions.

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  3. I have mixed feel ing about Holdren debunking Pielke.  The downside is why Holdren bothered trying to enagage and reason with a bit player like Pielke, it just feed's Pielke's ego, not to mention that Pielke just loves attention.

    On the up side, a highly respected and influential figure has finally called Pielke on his repeated misleading comments, misinformation and misrepresentation of the facts.  Footnotes or not-- including key information in footnotes just highlights the fact that Pielke is not being 100% honest with his audience, yet Pielke is ironically trying to use his conscious decision to claim his innocence ;) Fail.

    Pielke has been quite slippery in the language he has used (and also what he has chosen to highlight or ignore for that matter) to appease the Republicans and help Republicans in their ongoing agenda to stand in the way of the USA reducing GHG emissions.

    This episode has tarnished Pielke's reputation and his claim to be a supposed "honest broeker", and rightly so. Pielke walks a fine line between right and wrong and it was just a matter of time before he went over the line and got called out.

    After Spencer (an infamous "skeptic") completely lost it in public recently, he is probably not going to be called to testify on behalf of the Republicans (the 3% has become even smaller).  Fortunately, Pielke (a political scientist) will likely be only too happy to come to the aid of the obstructionist and ant-science Republicans when they next try to undermine climate science. 

    PS: It is interesting, Pielke allegedly voted for Obama and was happy with the appointement of Holdren as science advisor. Yet Pielke is only to happy to repeatedly help the Republicans stall on addressing AGW.

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  4. In RPjr's senate testimony he stated that his models of future hurricane activity response to climate change, if perturbed to align with worst case model projections (I assume a 36% increase in extreme hurricane (3+) landfalls by 2100, that these events would not produce a stastically significant result for several decades.

    I would like to know just how many extreme hurricane landfall events were needed between now and then to produce a statistically significant result.

    Then I would want to see a total cost, in lives lost and economic damages for the sum of those events.

    Finally, I would like to see the same projections (lives and cost), scaled out to 2200 for the climate response that results from maintaining BAU emissions for those "several decades" while we wait for the statistically significant trend to surface, and only then engaging in significant mitigation activities.

    I am guessing that his model would show at least 14 significant major hurricane landfall events, above those that would have happened absent of global warming, for a total sum cost approaching 650 billion dollars and hundreds of lives lost.

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  5. The article calls ... "Dr. Roger Pielke, Jr., a University of Colorado political scientist."  

    I thought he was an atmospherric scientist and, as such, should know what he is talking about - though he has a long record of showing the opposite.

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  6. Riduna:

    Dr. Roger Pielke Sr. is an atmospheric scientist. Junior is not. Senior carries different baggage, but they are both on the same train, hence it can be hard to keep them apart when reading about them.

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  7. Pielke junior's rhetoric really does appeal to the anti-science crowd and right-wing ideologues out there.  Here are some exmaples of the sort of comments Pielke junior permitted on his blog post about Holdren:

    "Holdren has been a nutcase since the 1970s, when he was promoting a scientifically lunatic theory of 'thermal pollution'..."

    "If John Holdren was someone you had just met socially, and he expressed the views he has held for the past thirty years, you would immediatly conclude that he is a lunatic. "

    Nice crowd ;) Not only did Pielke let those comments stand, but he did not even challenge them.  Tacit agreement then?

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  8. I note with surprise that the link to Pielke's response to this article that had been provided by Russ R has been deleted. Here it is again.

    Pielke makes the issue all about him. He makes the first, and foremost issue the fact that Holdren, under questioning in his testimony before Congress says, "The first few people you quoted [ie, Spencer and Pielke Jr] are not representative of the mainstream scientific opinion on this point". In his response, Pielke writes:
    "To accuse an academic of holding views that lie outside the scientific mainstream is the sort of delegitimizing talk that is of course common on blogs in the climate wars. But it is rare for political appointee in any capacity -- the president's science advisor no less -- to accuse an individual academic of holding views are are not simply wrong, but in fact scientifically illegitimate. Very strong stuff."

    This claim is, however, complete nonsense. To be outside the mainstream is simply to hold a distinctly minority view. All sorts of scientists have held distinctly minority views in the past, including Einstein with respect to the interpretation of quantum mechanics. Nobody thinks that Einstein was a worse scientist for that. Others who have held views distinctly outside the mainstream include Darwin, Wegener, and Hansen (who is outside the mainstream on the potential rate of future sea level rise, and on the possibility of runaway global warming). I certainly do not think less of any of those scientists for daring to be different. What matters is not whether or not you agree or disagree with the mainstream, but how you go about doing so.

    In fact, Pielke, if taken seriously has just condemned Spencer, Christie, Singer, Salby, Pielke Snr, and so on (in a distressingly long list) who are definitely outside the mainstream on climate science "...of holding views are are not simply wrong, but in fact scientifically illegitimate". In some cases, I would agree with that assessment, but that is based on how they defend their views, not on the nature of the views themselves. Inconstrast, according to Pielke, having a distinctly minority opinion in science means your views are "wrong" and "scientifically illegitimate". As I said, complete nonsense.
    Pielke's own words, however, contrast with Pielke's extreme sensitivity to Holdren's comments. In particular, in response to Holdren's original testimony, Pielke tweeted:

    "That's right, thanks. The zombies will always be with us. But it is brazen for zombie science to show up in the White House!"

    I am not sure what is meant by "zombie science", but the term is clearly not meant to be flattering. It would appear in fact to be an attempt at "...the sort of delegitimizing talk that is of course common on blogs in the climate wars" (to quote Pielke). As seems often to be the case, Pielke appears to be hypocritical on this point. He is happy to do to others what he will not tolerate the slightest appearance of others doing to him.

    Pielke also spends some time defending the claim that he left out vital information on the basis that he included it in a footnote. That is an odd defense. What he is charged with is not agreeing that there has been a trend towards droughts in the South West of the US. The evidence is that when he quoted CCSP report, he left out the second sentence which explicitly discusses situation in the SW US (see OP).

    On this issue, I am first going to make a very technical point. Holdren says:

    "[Any] reference to the CCSP 2008 report in this context should include not just the sentence highlighted in Dr. Pielke’s testimony but also the sentence that follows immediately in the relevant passage from that document and which relates specifically to the American West."

    The point here is that he did not say (contrary to Pielke) that Pielke did not include the crucial sentence in the report. He said that any reference should include both. Crucially, a reference is an individual act of refering to some source. If you have a ten page report, and refer to Bloggs et al (1880) in the first page, and again on the tenth, that is two seperate references to Bloggs et al. In like maner, if you refer to Bloggs et al in the text, and then in a footnote, that is two seperate references to Bloggs et .

    The reason it is two seperate references is that, in the text you will have made some comment on the quote or reference. You will have indicated agreement, disagreement, or that it only expresses the opinion of Bloggs et al, etc. These comments do not apply the quotation or reference in the footnote. That is a crucial point.

    In his published testimony (later quoted by Senator Sessions), Pielke wrote:

    What the IPCC SREX (2012) says:
    “There is medium confidence that since the 1950s some regions of the world have experienced a trend to more intense and longer droughts, in particular in southern Europe and West Africa, but in some regions droughts have become less frequent, less intense, or shorter, for example, in central North America and northwestern Australia.”
    For the US the CCSP (2008)20 says: “droughts have, for the most part, become shorter, less frequent, and cover a smaller portion of the U. S. over the last century.”21
    What the data says:

    8. Drought has “for the most part, become shorter, less frequent, and cover a smaller portion of the U. S. over the last century.”"
    (Emphasis in original)

    Earlier, in his "take home points", he had written:

    'Drought has “for the most part, become shorter, less frequent, and cover a smaller portion of the U. S. over the last century.”'

    He liked that clause so much that he repeated it three times, once in bold. That is three seperate references to the same sentence in CCSP (2008). In the final one, he prefaces the quote by saying that it is "What the data says". There can be no doubt in anybodies mind that Pielke not only agreed with this claim, but thought it a crucial claim that needed to be hammered home.

    In constrast, the immediately following sentence is confined to a single footnote. The footnote reads:

    'CCSP (2008) notes that “the main exception is the Southwest and parts of the interior of the West, where increased temperature has led to rising drought trends.”'

    So, whereas we are told by Pielke that the lack of an overall US trend is a "take home point", and "What the data says"; it is merely footnoted that the CCSP notes the trends in the Southwest of the US. I should not need to mention that merely noting that somebody says something does not also note your agreement. It is not legitimate to infer Pielke's agreement with the CCSP from his footnote.

    More importantly, it was not possible from Pielke's footnote to determine the relative importance accorded by the CCSP to the two sentences quoted by Pielke. Orphaning the second sentence in a footnote deprives it of context, underplaying it. More crucially, it deprives the preceding sentence of context, over emphasising it. As though that was not enough, Pielke then hammered the point three times.

    From this, it is clear that Pielke did not include the second sentence in any reference to the first, as suggested by Holdren. On the contrary, he referenced the first sentence three times, without including the second sentence - but then included a fourth reference to the CCSP (2008), ie, on to the second sentence in a footnote. As a result, he massively distorted the relative importance of the two sentences in the CCSP, to the point that his practise represents blatant quotation out of context. As a further result, it was not possible from his testimony to determine that he even agreed with the second sentence, and has not been possible until his response to Holdren.

    This post is long enough as is, so I will not discuss the further points at issue between Holdren and Pielke, which SFAICT, depend largely on Pielke misinterpreting Holdren, in part by ignoring the fact that Holdren's article was not just a response to Pielke, but primarilly a response to Senator Sessions.

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    Moderator Response:

    [RH] Russ' post was deleted based on the "no link only posts" rule. No problems with citing Pielke's link in the context of some discussion.

  9. Further to my post above, here are Pielke Jr's tweets in response to 

    "Roger Pielke Jr. ‏@RogerPielkeJr Feb 14
    1/3 John Holdren vs. IPCC on drought

    Roger Pielke Jr. ‏@RogerPielkeJr Feb 14
    2/3 Holdren: "we are seeing droughts in drought-prone regions becoming more frequent, more severe and longer" …

    Roger Pielke Jr. ‏@RogerPielkeJr Feb 14
    3/3 IPCC 2013: "not enough evidence at present to suggest more than low confidence in a global-scale observed trend in drought"

    Roger Pielke Jr. ‏@RogerPielkeJr Feb 14
    IPCC on drought "low-confidence" vs. Holdren "one of the better-understood dimensions" Paging IPCC authors, climate scis .... anyone care?

    Roger Pielke Jr. ‏@RogerPielkeJr Feb 14
    US Govt report "droughts have, for the most part, become shorter, less frequent and cover a smaller portion of the US over the last century"

    Roger Pielke Jr. ‏@RogerPielkeJr Feb 14
    Nature paper 2012 "Little change in global drought over the past 60 years" …

    Roger Pielke Jr. ‏@RogerPielkeJr Feb 14
    Holdren: "global climate change is increasing the intensity and the frequency and the life of drought" …

    Roger Pielke Jr. ‏@RogerPielkeJr Feb 14
    If climate scientists want more credibility they are going to have to look at wrong things said by their political friends, not just enemies

    Roger Pielke Jr. ‏@RogerPielkeJr Feb 14
    OK, enough on the drought nonsense, did you hear about those fancy skate suits? …

    Roger Pielke Jr. ‏@RogerPielkeJr Feb 14
    @andersbolling That's right, thanks. The zombies will always be with us. But it is brazen for zombie science to show up in the White House!"

    It should be noted that these are in response to Holdren's comments on Feb 14th to the press, not his testimony before Congress.  Consequently, the comments Pielke addresses have not made any reference to Pielke.  Further, they explicitly address the issue of drought in the SW of the US, and specifically California.  Despite this, Pielke's favourite sentence from the CCSP (2008) pops up yet again, with no reference to the following sentence which explicitly addresses the region Holdren was referring to.

    Further, he quotes the IPCC on global trends, but the IPCC SREX says regarding trends:

    "Global-scale trends in a specific extreme may be either more reliable (e.g., for temperature extremes) or less reliable (e.g., for droughts) than some regional-scale trends, depending on the geographical uniformity of the trends in the specific extreme."

    So though he puts himself forward as championing the IPCC position, he ignores the IPCC's statements of the relative importance of global vs regional trends when it comes to understanding drought. 

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  10. And in the end Pielke's repetition of one sentence that conveyed what he wanted to say while including the counter point in a footnote is simply a case of Plausible Deniability. He can give one message, his preferred one, in the full expectation that most readers/listeners will only take in that fact (how many of the senators are actually likely to read every footnote in the written text; how many will actually read the written submission).

    Then if someone calls him out on it as Holdren did he can splutter indignantly and say 'see, see I did say that as well!'

    Perfect, textbook Plausible Deniability at work.


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  11. Hi Tom C.,

    That was a very impressive and thorough analysis. You understand the "game" that Pielke junior likes to play very well.

    Also, I too have caught Pielke junior misrepresenting the IPCC SREX by omitting key sentences from the text that do not fit with his biased narrative.

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  12. The footnote may provide plausible deniability, but it also proves that he was intentioanlly deceiving people by hiding relevant information. I don't see how anybody could in good faith leave that second sentence out of the main text when it addressed the central question at hand.

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