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Monday, June 3, 2013

Denier Weirdness: Don't count climate science papers to "prove" there's no consensus!

Sou | 2:49 AM Go to the first of 8 comments. Add a comment


An economist, Richard Tol, is feeling a bit left out and lonesome.  So he has started hobnobbing with science deniers like Anthony Watts of  WUWT (and even the idiot poptech), courting them for attention.  He's protesting the 97% scientific consensus that humans are causing global warming.  Let's see what he has to say - we'll start with Anthony Watts version of Tol on WUWT.

The basic argument seems to be that Cook13 shouldn't have counted the papers that are about climate science - you know, scientific papers on the impacts of global warming, or applied science papers on mitigation.  If you thought Richard Tol had odd ideas, here's the proof. (We already know Anthony Watts has odd ideas.)


Arithmetic fail


Let's start with some basic arithmetic.  For an economist, Richard Tol is not very good at arithmetic.  He gets the following wrong saying he's using data from Cook13.  Either he's not using that data or he can't do arithmetic - he calculates 98% somehow, when the answer is 97.1%:

3896/(3896+78+40) = 98%  
No, Richard, it equals 97.1% just like the paper says.

Anthony is not very good at peer/pal/blog review or he would have picked that up.


Neutral vs No Position


Richard keeps talking about a "neutral" category.  There is no such category in Cook13.  Now I'm not sure if English is Richard's first language, so I'll hold back on questioning his ability to understand the difference between "neutral" and "no position".  It's an important difference.

  • "Neutral" could indicate a half-way point between two extremes. Global warming being caused by humans and global warming being caused by other means.  
  • "No position" means just that.  The authors will be likely to know full well that global warming is caused by humans, but the particular abstract in question does not allude to the cause.  That is a different meaning to "neutral".



Making up his own rules - toss out the bulk of climate science research, says Richard


Anthony quotes Richard Tol saying 35% of abstracts were 'misclassified'.  He didn't say why, so I went to Richard's article (yes, he went ahead and tried to justify his tweets!) and found this:
The majority of the selected papers are not on climate change itself, but rather on its impacts or on climate policy. The causes for climate change are irrelevant for its impact. Therefore, impact papers should be rated as neutral.
The causes of climate change are irrelevant to the impact of climate change so should be rated as neutral?  What? Why?

Impacts are defined in Cook13 as: Effects and impacts of climate change on the environment, ecosystems or humanity.  Impacts papers constitute the biggest single component of climate science research, comprising 48.4% of the abstracts examined in Cook13.  It would be nonsense to rate them all "neutral" (which isn't a category anyway) or "no position" - when the cause of global warming may be a fundamental aspect of the research.

I looked up one such abstract.  It was rated by Cook13 as "Explicit endorsement without quantification - Explicitly states humans are causing global warming or refers to anthropogenic global warming/climate change as a known fact"

Here is the abstract (excerpt from a longer abstract, my bold):
A complex earth system model, simulating atmosphere and ocean dynamics, marine biogeochemistry, terrestrial vegetation and ice sheets, was used to study feedbacks between the terrestrial biosphere and climate with a set of long-term climate change ensemble experiments. CO2 emissions were assigned according to historical data and the IPCC SRES scenarios B1, A1B and A2, followed by an exponential decay of the emissions for the period 2100–3000. The experiments give a reasonable reconstruction of the measured CO2 concentrations between 1750 and 2000. Maximum atmospheric CO2 concentrations of 520 ppm (B1), 860 ppm (A1B) and 1680 ppm (A2) were reached between 2200 and 2500. Additional experiments were performed with CO2 emissions and suppressed climate change, as well as an experiment with a prescribed land surface. The experiments were repeated with the vegetation model driven offline, to investigate the effects of climate and CO2 changes separately. The biogeochemical and biogeophysical interactions between terrestrial biosphere and atmosphere were quantified and compared.

Clearly the cause of global warming is critical if one is to estimate its progression.  The major forcing is CO2, therefore emissions of CO2 will determine the impact. The above paper refers to the different impacts of global warming, depending on the scenario.  Richard Tol is very wrong in his 'rule' to rate "impact" papers as "neutral".  He's not a scientist, that's quite clear.


While we're at it, toss out most of the rest of the research, says Richard


Richard then says to chop out even more papers, based on another of Richard's own made up "rules":
However, a paper discussing, say, carbon capture and storage cannot be taken as evidence for global warming. These papers should therefore also be rated as neutral.

Why? On what grounds?  Mitigation papers constitute the next largest category, or 28.3% of the abstracts in the Cook13 sample.  I found papers on carbon capture and storage that had different ratings - some were rated as endorsing AGW and others as taking no position.

This one was rated as implicitly endorsing AGW based on this abstract (excerpt only and my bold):
Coal-fired power plants account for nearly 50% of U.S. electricity supply and about a third of U.S. emissions of CO2, the major greenhouse gas (GHG) associated with global climate change. Thermal power plants also account for 39% of all freshwater withdrawals in the U.S. To reduce GHG emissions from coal-fired plants, postcombustion carbon capture and storage (CCS) systems are receiving considerable attention.
This one as taking no position on AGW:
The evaluation of life cycle greenhouse gas emissions from power generation with carbon capture and storage (CCS) is a critical factor in energy and policy analysis. The current paper examines life cycle emissions from three types of fossil-fuel-based power plants, namely supercritical pulverized coal (super-PC), natural gas combined cycle (NGCC) and integrated gasification combined cycle (IGCC), with and without CCS. Results show that, for a 90% CO2 capture efficiency, life cycle GHG emissions are reduced by 75–84% depending on what technology is used. With GHG emissions less than 170 g/kWh, IGCC technology is found to be favorable to NGCC with CCS. Sensitivity analysis reveals that, for coal power plants, varying the CO2 capture efficiency and the coal transport distance has a more pronounced effect on life cycle GHG emissions than changing the length of CO2 transport pipeline. Finally, it is concluded from the current study that while the global warming potential is reduced when MEA-based CO2 capture is employed, the increase in other air pollutants such as NOx and NH3 leads to higher eutrophication and acidification potentials.
(If I were rating the above I'd probably rate it as "implicit" rather than "no position" based on the last sentence in particular.  That suggests that marginal decisions probably balance out in the long run, or that the reviewers if they erred, tended to err on the conservative side when it came to categorising the abstracts.)


Who's the denier, Richard?


Now if Richard took out all the "impacts" papers and all the "mitigation" papers, he'd be tossing out the bulk of climate research - in fact he'd toss out 77% of the literature.  He'd be left with just the following:
  • Methods - Focus on measurements and modeling methods, or basic climate science not included in the other categories
  • Paleoclimate - Examining climate during pre-industrial times
Richard Tol needs to rethink his "analysis".  He does sound like a typical denier, doesn't he.  Toss out all the papers on climate science and you'll surely be able to prove there's "no consensus".

Count the papers on climate science and there's a 97% consensus that humans are the cause of global warming.

Postscript

In the comments on WUWT the fake skeptics are very relieved that Anthony has told them they don't have to take any notice of yet another study.  They say they would have sat up and taken notice if 97% of science really and truly found that humans are causing global warming.  "What a relief", they say.  "Thank goodness for Anthony."  It means they can sit back and continue to deny reality.  It makes little difference that Tol himself has not disputed the 97% number.  They don't even seem aware of that fact.

One of the fake skeptics wants to give more weight to attribution studies and not count or give lesser weighting to research on impacts.  None of them seem aware that removing thousands of studies from the 'count' as Richard suggests, may not make any difference to the 97% number.

I have to wonder how many more thousands of studies deniers need before they accept that CO2 is a greenhouse gas and adding more of it to the air warms the planet?  How does their denial of human-induced global warming stack up against their certainty that H pylori exists?  Deniers often quote that discovery as 'proof' there will one day be a paper that the greenhouse effect doesn't happen.  How many papers did they need for "proof" of H pylori?  What about the helical structure of DNA?  Are they still waiting for the one paper that "proves" DNA doesn't exist?  Or maybe they are still waiting for the one paper that "proves" the earth is flat.

Tol says he's been told how the 97% is calculated, but no-one takes any notice.  They prefer his wrong version.  In any case, he doesn't explain it well, talking about 'reported data' and 'original data' implying there was some sort of dodgy activity instead of just admitting he got it wrong.  He is not coming out of this smelling of roses.  That doesn't matter to deniers and dismissives.  They lost their senses a long time ago, if they ever had any.


For more enlightenment on the different shades of denier weirdness plus a discussion of Cook13 by people closer to the research than I am, visit Eli's blog.

8 comments:

  1. You forgot to mention that Tol is an advisor to the GWPF, a possible motivation for this self-immolation.

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    Replies
    1. I didn't know that, Rattus but yes, that could explain his apparent stupidity (and the dubious company he seeks).

      Peiser and Lawson are not shy about making fools of themselves and each other in public. It makes sense that Tol would follow suit to keep in their 'good graces'.

      Delete
  2. Actually Tol is definitely a scientist in the clerical sense (if you count economics as a science ;-9) with a very nice publication record. He is also well at home in the statistical techniques as used in economics/econometrics. Which makes the current silliness even less forgiveable.

    BTW I think Tol's computation is 3896/(3896+78) = 98%. Why leaving out the 40 ("Uncertain on AGW") is unclear to me. IMHO someone opining that the cause of GW is not known with some confidence to be A steps definitely outside the consensus (i.e., takes a position).

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    Replies
    1. Martin, yes. The paper is very clear about what constitutes taking a position. There are three categories of "taking a position": 1) human activity is the main cause, 2) human activity is 50% or less of the cause and 3) humanity's role in regard to global warming is uncertain or undefined.

      I think Richard's error regarding "neutral" and "no position" is not dissimilar in that both errors indicate sloppy thinking on his part. Scientists need to be precise.

      Is he as sloppy when he sticks to his own field of study I wonder? I'm not familiar with his work at the detail level.

      Delete
    2. This is an example of a fine paper by Tol, from a while ago

      Delete
  3. I find Tols non representative sample comments a bit rich considering his own record: "Richard Tol, in a comment on Bishop Hill, suggests that his forthcoming literature review of SCC estimates should be used instead of our analysis. In that article, updating his similar, earlier review, he includes 311 estimates, of which 184 (59%) come from his own publications. Those who want a Tol-centric review of the SCC literature should certainly consult his periodic updates, although readers should realize that these articles are self-referential to an extent that is unusual in academic literature reviews."

    This is written by Frack Ackermann here http://triplecrisis.com/for-whom-the-blog-tols/

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  4. Tol clearly believes he deserves more bites at the apple. FWIW he actually makes a strong argument for weighting any survey by looking at an author's last paper only.

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  5. Cook et al. clearly define the set they are considering. They sift through them all, and report the results of this. This set is not a sample, it is the entire population as defined in their paper. You can argue for different selection rules for what papers to study, but you will always have to draw a line somewhere and it is always going to be a judgement call. I have a hard time believing that Tols proposed criteria would change the conclusions qualitatively. I would like to see Tol estimate the quantitative impact hos proposed changes would have. IMO the key is to clearly define what is being studied, and that there is minimal/no wiggle space to manipulate the results.

    @elirabett : It should be easy to cull the Cook set to only one paper per author to check what results that would give.

    ReplyDelete

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