Arguments
Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
Posted on 16 May 2013 by dana1981, John Cook
A new survey of over 12,000 peer-reviewed climate science papers by our citizen science team at Skeptical Science has found a 97% consensus among papers taking a position on the cause of global warming in the peer-reviewed literature that humans are responsible.
Lead author John Cook created a short video abstract summarizing the study:
The Abstracts Survey
The first step of our approach involved expanding the original survey of the peer-reviewed scientific literature in Oreskes (2004). We performed a keyword search of peer-reviewed scientific journal publications (in the ISI Web of Science) for the terms 'global warming' and 'global climate change' between the years 1991 and 2011, which returned over 12,000 papers. John Cook created a web-based system that would randomly display a paper's abstract (summary). We agreed upon definitions of possible categories: explicit or implicit endorsement of human-caused global warming, no position, and implicit or explicit rejection (or minimization of the human influence).
Our approach was also similar to that taken by James Powell, as illustrated in the popular graphic below. Powell examined nearly 14,000 abstracts, searching for explicit rejections of human-caused global warming, finding only 24. We took this approach further, also looking at implicit rejections, no opinions, and implicit/explicit endorsements.
We took a conservative approach in our ratings. For example, a study which takes it for granted that global warming will continue for the foreseeable future could easily be put into the implicit endorsement category; there is no reason to expect global warming to continue indefinitely unless humans are causing it. However, unless an abstract included (either implicit or explicit) language about the cause of the warming, we categorized it as 'no position'.
Note that John Cook also initiated a spinoff from the project with a survey of climate blog participants re-rating a subset of these same abstracts. However, this spinoff is not a part of our research or conclusions.
The Team
A team of Skeptical Science volunteers proceeded to categorize the 12,000 abstracts – the most comprehensive survey of its kind to date. Each paper was rated independently at least twice, with the identity of the other co-rater not known. A dozen team members completed most of the 24,000+ ratings. There was no funding provided for this project; all the work was performed on a purely voluntary basis.
Once we finished the 24,000+ ratings, we went back and checked the abstracts where there were disagreements. If the disagreement about a given paper couldn't be settled by the two initial raters, a third person acted as the tie-breaker.
The volunteers were an internationally diverse group. Team members' home countries included Australia, USA, Canada, UK, New Zealand, Germany, Finland, and Italy.
The Self-Ratings
As an independent test of the measured consensus, we also emailed over 8,500 authors and asked them to rate their own papers using our same categories. The most appropriate expert to rate the level of endorsement of a published paper is the author of the paper, after all. We received responses from 1,200 scientists who rated a total of over 2,100 papers. Unlike our team's ratings that only considered the summary of each paper presented in the abstract, the scientists considered the entire paper in the self-ratings.
The 97% Consensus Results
Based on our abstract ratings, we found that just over 4,000 papers expressed a position on the cause of global warming, 97.1% of which endorsed human-caused global warming. In the self-ratings, nearly 1,400 papers were rated as taking a position, 97.2% of which endorsed human-caused global warming.
We found that about two-thirds of papers didn't express a position on the subject in the abstract, which confirms that we were conservative in our initial abstract ratings. This result isn't surprising for two reasons: 1) most journals have strict word limits for their abstracts, and 2) frankly, every scientist doing climate research knows humans are causing global warming. There's no longer a need to state something so obvious. For example, would you expect every geological paper to note in its abstract that the Earth is a spherical body that orbits the sun?
This result was also predicted by Oreskes (2007), which noted that scientists
"...generally focus their discussions on questions that are still disputed or unanswered rather than on matters about which everyone agrees"
However, according to the author self-ratings, nearly two-thirds of the papers in our survey do express a position on the subject somewhere in the paper.
We also found that the consensus has strengthened gradually over time. The slow rate reflects that there has been little room to grow, because the consensus on human-caused global warming has generally always been over 90% since 1991. Nevertheless, in both the abstract ratings and self-ratings, we found that the consensus has grown to about 98% as of 2011.
Percentage of papers endorsing the consensus among only papers that express a position endorsing or rejecting the consensus. From Cook et al. (2013).
Our results are also consistent with previous research finding a 97% consensus amongst climate experts on the human cause of global warming. Doran and Zimmerman (2009) surveyed Earth scientists, and found that of the 77 scientists responding to their survey who are actively publishing climate science research, 75 (97.4%) agreed that "human activity is a significant contributing factor in changing mean global temperatures." Anderegg et al. (2010) compiled a list of 908 researchers with at least 20 peer-reviewed climate publications. They found that:
"≈97% of self-identified actively publishing climate scientists agree with the tenets of ACC [anthropogenic climate change]"
In our survey, among scientists who expressed a position on AGW in their abstract, 98.4% endorsed the consensus. This is greater than 97% consensus of peer-reviewed papers because endorsement papers had more authors than rejection papers, on average. Thus there is a 97.1% consensus in the peer-reviewed literature, and a 98.4% consensus amongst scientists researching climate change.
Why is this Important?
Several studies have shown that people who correctly perceive the scientific consensus on human-caused global warming are more likely to support government action to curb greenhouse gas emissions. This was most recently shown in McCright et al. (2013), recently published in the journal Climatic Change. People will defer to the judgment of experts, and they trust climate scientists on the subject of global warming.
However, research has also shown that the public is misinformed on the climate consensus. For example, a 2012 poll from US Pew Research Center found less than half of Americans thought that scientists agreed that humans were causing global warming. One contributor to this misperception is false balance in the media, particularly in the US, where most climate stories are "balanced" with a "skeptic" perspective. However, this results in making the 3% seem much larger, like 50%. In trying to achieve "balance", the media has actually created a very unbalanced perception of reality. As a result, people believe scientists are still split about what's causing global warming, and therefore there is not nearly enough public support or motivation to solve the problem.
Such false balance has long been the goal of a dedicated misinformation campaign waged by the fossil fuel industry. Just as one example, in 1991 Western Fuels Association conducted a $510,000 campaign whose primary goal was to "reposition global warming as theory (not fact)." These vested interests have exploited the media desire to appear "balanced."
Open Access for Maximum Transparency
We chose to submit our paper to Environmental Research Letters because it is a well-respected, high-impact journal, but also because it offers the option of making a paper available by open access, meaning that for an up-front fee, the paper can be made free for anybody to download. This was important to us, because we want our results to be as accessible and transparent as possible.
To pay the open access fee, in keeping with the citizen science approach, we asked for donations from Skeptical Science readers. We received over 50 donations in less than 10 hours to fully crowd-fund the $1,600 open access cost.
Human-Caused Global Warming
We fully anticipate that some climate contrarians will respond by saying "we don't dispute that humans cause some global warming." First of all, there are a lot of people who do dispute that there is a consensus that humans cause any global warming. Our paper shows that their position is not supported in the scientific literature.
Second, we did look for papers that quantify the human contribution to global warming, and most are not that specific. However, as noted above, if a paper minimized the human contribution, we classified that as a rejection. For example, if a paper were to say "the sun caused most of the global warming over the past century," that would be included in the less than 3% of papers in the rejection categories.
Many studies simply defer to the expert summary of climate science research put together by the Intergovernmental Panel on Climate Change (IPCC), which states that most of the global warming since the mid-20th century has been caused by humans. According to recent research, that statement is actually too conservative.
Of the papers that specifically examine the human and natural causes of global warming, virtually all conclude that humans are the dominant cause over the past 50 to 100 years.
Net human and natural percent contributions to the observed global surface warming over the past 50-65 years according to Tett et al. 2000 (T00, dark blue), Meehl et al. 2004 (M04, red), Stone et al. 2007 (S07, light green), Lean and Rind 2008 (LR08, purple), Huber and Knutti 2011 (HK11, light blue), Gillett et al. 2012 (G12, orange), Wigley and Santer 2012 (WS12, dark green), and Jones et al. 2013 (J13, pink).
Most studies simply accept this fact and go on to examine the consequences of this human-caused global warming and associated climate change.
Another important point is that once you accept that humans are causing global warming, you must also accept that global warming is still happening; humans cause global warming by increasing the greenhouse effect, and our greenhouse gas emissions just keep accelerating. This ties in to our previous posts noting that global warming is accelerating; but that over the past decade, most of that warming has gone into the oceans (including the oft-neglected deep oceans). If you accept that humans are causing global warming, as over 97% of peer-reviewed scientific papers do, then this conclusion should not be at all controversial. With all this evidence for human-caused global warming, it couldn't simply have just stopped, so the heat must be going somewhere. Scientists have found it in the oceans.
Spread the Word
Awareness of the scientific consensus on human-caused global warming is a key factor in peoples' decisions whether or not to support action to reduce greenhouse gas emissions. However, there is a gap here due to the public's lack of awareness of the consensus. Thus it's critical that we make people aware of these results. To that end, design and advertising firm SJI Associates generously created a website pro-bono, centered around the results of our survey. The website can be viewed at TheConsensusProject.com, and it includes a page where relevant and useful graphics like the one at the top of this post can be shared. You can also follow The Consensus Project on Twitter @ConsensusProj, and on Facebook.
Quite possibly the most important thing to communicate about climate change is that there is a 97% consensus amongst the scientific experts and scientific research that humans are causing global warming. Let's spread the word and close the consensus gap.
Coming tomorrow, details about a feature that will let you test our results by rating the papers directly yourself. The Consensus Project results have also been incorporated into the rebuttals to the myths There is no consensus and IPCC is alarmist.
barry @146, the criticism that several of the abstracts were publicly discussed on the SkS forum, contrary to the statement in the paper that ratings were "independent" at the first stage, is correct. I do not have a hard figure on how many were discussed, but it is more than 10 and likely less than 20. Of those discussed, many (possibly most) were simply posted with a note that it was odd, or interesting and with no discussion of the appropriate classification or rating. Others were posted with the posters own classification but no further discussion.
These instances do contradict the claim in the paper that, "Each abstract was categorized by two independent, anonymized raters." With just 10 to 20 instances, ie, less than 0.2% of instances, to say the claim that the raters were not independent would be misleading. Never-the-less it could be argued that these abstracts should be excluded from the analysis. Of course, from among those I have examined, the were either excluded as "not climate related", rated as neutral or, in one instance, rated as rejecting the consensus. Consequently I don't expect any demands in that direction.
Given the very low number of abstracts involved and the very high number of abstracts surveyed, there is no question of these instances having distorted the result. Indeed, it is not even known that it would have changed the rating of any given paper so it is entirely possible that it would have no effect on the result.
Curiously, the only instance that contained extensive discussion the appropriate rating, and the instance used as an example by Brandon Shollenberger at Lucia's was Cool dudes: The denial of climate change among conservative white males in the United States. What he does not mention was that it was rated as neutral and excluded at not climate related. Given that it is an analysis of the effects of gender, race and politics (conservative white males) on acceptance of climate change denial, who could disagree? Of course, it takes all of 5 seconds on the SkS concensus project searchable database to find out that information - far too much time to be expected to spend on research before you start slinging accusations /sarc
In fact, the only person at Lucia's to have mounted criticisms of any seriousness is Lucia herself. I think she is wrong either on the substance of significance of her criticisms but at least they are criticisms worthy of consideration. The rest of the criticisms are completely inconsequential, absurd, or in at least one case outright dishonest.
Jason,
Yes, twice in the public survey rating the 10 abstracts. The second time i loked up the full papers to see how the full text compared with the abstracts. I found, as most others did, that the full papers were more likely to express an opinion that the abstracts. I believe I understand what neutral means, and I certainly don't think it implies a rejection of the consensus. But neither does it imply endorsement.
I disagree that options 1, 2 and 3 support an endorsement of the anthropogenic influence of global warming is greater than 50%. only option does.
The endorsement statement in the email received by original authors is given in the supplementary material.
Can you explain how options 2) and 3) endorse a >50% contribution to global warming from humans?
A comment disappeared - don't know if my posting status has changed.
Jason, i've read the paper and the supplementary material quite carefully. The supplementary material gives the email sent to original authors with the endorsement statemtn (which mentions nothing about degree of human influence) and the options. Can you explain how options 2) and 3) endorse >50% human influence on global warming? I don't think they do at all. Only 1) specifically states this. The other 2 are unquantified, as the paper attests.
I don't believe 97% of papers/abstracts gave exlicit endorsement 1) to the notion that human activity is responsible for global warming. I think 97% of papers gave unquantified + explicitly quantified endorsement that AGW is happening.
Amendment
"I don't believe 97% of papers/abstracts gave exlicit endorsement 1) to the notion that human activity is >50% responsible for global warming. I think 97% of papers gave unquantified + explicitly quantified endorsement that AGW is happening."
barry - Two comments, with the understanding that the "concensus on AGW" means AGW as the dominant force behind global warming:
First: The title is part of the definition of the categories, as viewed by both raters and authors. And category 2 "Explicit endorsement without quantification" is just that, endorsement of the AGW consensus. If a paper treats AGW as not the dominant influence, it's not endorsing the consensus, and shouldn't be rated as Category 2. Ratings are not just off the description (a refinement), but also the category title itself. And somehow, I cannot see an author whose paper rates AGW as a minority influence would voluntarily rate it as explicitly endorsing the consensus.
Second: Category 3, "Implicit Endorsement: Implies humans are causing global warming. E.g., research assumes greenhouse gas emissions cause warming without explicitly stating humans are the cause", is a clear endorsement of human caused global warming if you understand that greenhouse gas emissions are caused by humans.
Therefore, unless there is a statement in the abstract or paper that increases in GHGs such as CO2 are from natural causes, rather than anthropogenic (very much a minority view), this is indeed an endorsement of the consensus. Because, quite frankly, the evidence for human driven increases in CO2, CFCs, and the feedback from water vapor is overwhelming.
---
What is most amazing to me in these discussions (here and on sites like the Blackboard) is the push for one-sided filtering: that papers categorized as rejections are always rejections, but that somehow papers categorized as endorsements are not always endorsements. That seems overwhelmingly biased to me...
KR... Well, you know, they don't have much room to play with at 0.7% of the research. ;-)
First, I would like to commend you guys for putting the time and effort to do this. However, I think the 97% consesus is misleading.
The article states, "We found that about two-thirds of papers didn't express a position on the subject in the abstract, which confirms that we were conservative in our initial abstract ratings."
Thus, the 97% consensus is only for the papers that expressed a position on the topic of AGW. Therefore, out of the total sample size of 12,000, the number of papers that expressed support of AGW in their abstract was actually 32% . And 1% expressed disagreement or uncertainty with AGW. Thus, 67% of the abstracts didn't have a position.
The article further states,
"This result isn't surprising for two reasons: 1) most journals have strict word limits for their abstracts, and 2) frankly, every scientist doing climate research knows humans are causing global warming. There's no longer a need to state something so obvious. For example, would you expect every geological paper to note in its abstract that the Earth is a spherical body that orbits the sun?"
While the first one is true, it still doesn't tell us the author's position. The actual authors may or may not support AGW or maybe unsure. The second one looks like a personal opinion.
It seems illogical to just ignore the 67% of papers that didn't express an opinion in their abstracts. Especially since the keyword searches used to find the papers, "global warming" and "global climate change," are sensitive topics with proponents pushing for drastic emission reductions.
Also that UIC paper that is cited asked 2 questions in its online survey.
"1. When compared with pre-1800s levels, do you think that mean global temperatures have generally risen, fallen, or remained relatively constant?
2. Do you think human activity is a significant contributing factor in changing mean global temperatures?"
76 out of 79 climate scientists answered risen to question 1. The 97% consensus comes from the 75 out of 77 climate scientists that responded yes to question 2. But question 2 is subjective because it doesn't state what % is considered siginificant. Significant could be 10%, 20%, 50%, etc of observed warming. just my 2 cents.
barry,
Further to KR's comment, the reason I mentioned the 5, 6, and 7 categories was because each cateogory must be considered in the context of all the others. If the abstract says anything that can be interpreted as "human activity is <50% responsible for global warming" it would have automatically shunted it into category 5, 6, or 7, whether it was implying it, stating it, or exlicitly quantifying it.
And if it did not go either way, then it was neutral.
engineer @ 157... Well, no one ignored the "no position" papers. It's discussed quite extensively in the paper.
You're not noting the fact that, when the scientists rated their own papers, that 66% dropped to 35%, yet the consensus figure of papers that state a position stayed nearly the same. That, in and of itself, suggests a level of robustness to the conclusions.
engineer,
just my 2 cents.
I'd be asking for my money back.
Perhaps you haven't seen my earlier comment, among many others' comments that already addressed this point? Perhaps you can explain why a number that would be invariant regardless of how many irrelevant papers are considered is less important than a number that can be changed at will simply by adding more papers to the set of papers that must be manually considered?
To me, it seems illogical to include papers that are irrelevant to determining the question at hand but I look forward to your explanation.
Especially since the keyword searches used to find the papers, "global warming" and "global climate change," are sensitive topics with proponents pushing for drastic emission reductions.
Are they? Tell me, what topics should researchers use who are simply reporting on some scientific results so they can avoid these "sensitive topics" with unnamed "proponents"? That's what all the papers I looked at were doing, and, as I've mentioned before, all the "neutrals" I saw clearly accepted global warming was occurring (and were reporting on some aspect of the consequences), it's just that they didn't mention the cause of it in their abstracts. Since they did give any indication on the cause, they were irrelevant to the question at hand, just as the vast majority of papers published in the scientific literature. Should they be included in the total too, so the two percentages become ~0% and ~0% (while still maintaining the same ratio)? Or should we focus on the papers that actually have a bearing on the question at hand?
KR and Jason,
It seems I have been labouring under a misapprehension, then. But I wonder if I am alone in that. The email sent to original authors makes no mention of the consensus being about degree of warming. The Endorsement statement in the email only mention humans contributing, not being a primary source.
Then they get the 7 rating options, 2 of which are quantified, and the other 5 are qualified. The Author reading the email it must infer that all 7 ratings are under the rubric of >/<50% human influence, rather than (as I did) view the remaining 5 ratings as qualitative, rather than quantitative options. Scientists must make an assumption about that because it is not expressly stated, and in the manner that it is stated in the email, it does not mention degree of human influence at all.
Neither is it in the abstract of the paper. In fact, apart from options 1) and 7), only one sentence of the paper does mention degree of human influence, in the last sentence of the introduction. I find this confusing. The abstract mentions of the consensus position infers a simple accept/reject AGW. Eg,
Throughout the paper, apart from the one sentence in the intro, the values are tied to the phrase "the consensus" or similar.
Read straight, this could easily include a human contribution of less than 50%, and options 2, 3, 5 and 6, are qualitative options, and nothing to do with >/<50% hmuan contribution. IE, If an abstract seems to minimize the importance of the human contribution and gives no qantification, then it is rated 5 or 6, and if it emphasises the importance of the human contribution, but does not quantify, then it should be rated 2 or 3. (It's a shame a breakdown of ratings results is not included in the study/supplementary)
My concern now is, that with different interpretations of the consensus statement (and different scientific societies and position statements also word the consensus differently, some only going as far as saying that human activity is contributing to global warming), the original Authors may have rated as I did, applying to all but options 1 and 7 a qualitative interpretation of abstracts.
Possibly I am just ignorant or not too bright. They said so at Lucia's, where I have been arguing, against them there, that the 97% result has come from a simple accept/reject AGW. I really do find it incredible that 97% of abstracts endorse >50% human influence, implicatively or otherwise.
BTW, are any of the authors commenting here? It would be great if they did and identified themselves (unless they prefer anonymity), so that they could clear up misunderstandings.
Hey, John Cook, come straighten us out.
@ Jason B.
Climate change is a sensitive topic and proponents of AGW do mostly support drastic cuts in emissions. I don't know why you took offense to that statement.
Anyway, 7,930 papers (66%) had No AGW position. 1,339 of these were then self rated and of the 1,339 36% were self-rated as no position on AGW. Since you worked on the paper...How many of the No AGW Position papers and self rated No AGW Position were on the topic of climate change?
You're wondering why I consider the overall percentage number to be relevant. It is interesting that 66% of the overall 12,000 and 35% of the 2,142 respondents had no stated AGW position in their paper. Why? If those papers are on the topic of climate change (I don't know if they are that's why I asked the above question) and the authors support AGW, then I would expect them to mention human CO2 emissions because a) humans are driving climate change through emissions and b) we're running out of time and scientists have to convince governments that humans are behind climate change so we don't kill ourselves.
and reason number 2 doesn't cut it for me. " 2) frankly, every scientist doing climate research knows humans are causing global warming. There's no longer a need to state something so obvious. For example, would you expect every geological paper to note in its abstract that the Earth is a spherical body that orbits the sun?" The paper itself and the UIC survey cited above refute this. I doubt you can find a geologist that doesn't believe that the Earth is a spherical body orbiting the sun. just my 2 cents.
that's why I thought the 97% consensus was overemphasized.
Barry, very briefly (and for the last time for a while):
1) Lucia's argument that the IPCC consensus in 1990 was not that greater than 50% of warming due to anthropogenic factors is valid. The concensus position has evolved over time, a factor not properly recognized in the concensus project. How significant is that? Well, using the figures from Carrick's "scrape" of the data, I excluded all affirmations prior to 2001 but did not exclude any rejections. The result: Affirmations are 97.5% of the sum of all rejections and 2001 to 2011 affirmations. So, even if we exclude all affirmations prior to 2001 because the consensus position was not as well developed then, the result still stands.
2) Further, I also tried excluding all implicit affirmations (but no rejections) from the result. The result is that affirmations are still >80% of the sum of affirmations and rejections in all years, and average 95.35% of the sum of affirmations and rejections in all years. It cannot seriously be believed that 100% of implicit ratings are false positives, even on the stricter criterion that the projects participants believed applied (and rated according to). But even on that absurd assumption it makes nearly no difference to the result.
3) You are correct that authors may have used a less strict interpretation of the criteria than the abstract ratings. If true, however, it would merely partially explain why author ratings rated the papers as far more supportive of the concensus, and would have no implications about the validity of the abstract ratings.
So, even allowing absurd amounts of credence to the arguments of Mosher and Lucia, the actual impact on the result is minimal. Lucia keeps on saying she will get around to producing numbers to analyze her intuitions. Frankly, if she were serious she would not blog on the subject until she produced those numbers. I believe she relies on the fact that gullible people will accept her mere pointing to a possible flaw as thereby establishing a fatal flaw in the paper. In reality, however, she is at best nitpicking.
Finally, you can find out all the numbers you need for your own analysis by going to the searchable database and searching each distinct category (by year, rating and topic) with the search term "i". It takes about half an hour to get full tables of the data.
Bye now for a month or so.
Captain Bluetooth is also confused about the consensus
Engineer: Can you explain Captain Bluetooth's confusion?
Thanks to Tom.
Re-reading the thread at Lucia's, I see Zeke Hausfather reads the ratings much as I did, and I know he's no dummy. So if he did, and I did (and some others at Lucia's), how many original authors did?
Regarding Tom' points, if original Authors believed that options 2, 3, 5 and 6 were not related to >/<50% influence, but qualitative statements, then that may have a significant impact on results expected under the rubric given here. Almost everyone agrees, including the (better-informed) skeptics, that AGW is real and happening. This is the public perception that John Cook has stated he is combatting with this paper - that AGW is real and happening, which public announcements may also have confused me and others as to what the consensus position is that the paper is investigating.
A concise statement in the abstract of what the "consensus position" is as investigated by the paper would have obviated a considerable amount of confusion.
Engineer wrote "Why? If those papers are on the topic of climate change ... and the authors support AGW, then I would expect them to mention human CO2 emissions"
I can give you an example with which I am familiar. I have done some work on statistical downscaling (essentially trying to work out how climate change will effect sub-regional scale climate from the larger scale climate projections provided by GCMs). As this only looks at the statistical relationships between large scale and sub-regional climate it is pretty much independent of the cause of the climate change. This means that there is no specific need to take a stance on the cause of the climate change as it isn't directly relevant to the methods described in the paper. Some papers do mention emissions scenarios (IIRC the paper I authored [which isn't in the survey] does, but I can't remember if it explicitly attributes any proportion of climate change to anthropogenic emissions), and some don't, basically at the author sees fit.
Something worth bearing in mind is that scientific papers are generally written for other scientists, not for the general public,and they definitely are not generally written to resolve common myths in climate blogs (although there are exceptions). As a result, they tend not to state the bleedin' obvious, and they tend not to draw conclusions on topics that are not directly supported by the evidence presented in the paper. In the case of a downscaling paper, the results basically show how well you can predict historical local climate from supra-regional climate, so it doesn't in itself say anything about the cause of climate change, even though the authors fully agree with the mainstream position on attribution.
Essentially, not all papers on climate change are on the question of what causes how much of it, so not all papers explicitly make a statement on attribution.
I look forward to your answer to Cap'n Bluetooth's conundrum ;o)
@ Kevin...You didn't understand my post at all. I don't disagree with the 97% number. It's like voting if people don't vote they're not part of the total so u use the subset that actually voted. But that's not my point. Please read my comment 162 to understand what I'm talking about. Whatever, it was just my opinion on the topic anyway.
barry,
The proposition put to the authors in the email is "that human activity (i.e., anthropogenic greenhouse gases) is causing global warming (e.g., the increase in temperature)", as you quoted. They were asked to assign the level of endorsement of their paper to the proposition that human activity is causing global warming. If you read the description of each level you'll see that the difference between 1, 2, and 3 is not how strongly they agree with that proposition, nor what percentage of human involvement there is, but rather the manner in which that endorsement was expressed.
In other words, it is not that level 1 is "I am absolutely certain that humans are responsible for > 50%" and level 3 is "I'm reasonably sure that humans are responsible for > 50%" (i.e. degree of confidence), or that level 1 is "Humans are responsible for > 50%" and level 3 is "Humans are responsible for > 10%" (i.e. degree of responsibility), but rather than level 1 is explicitly stating the percentage of human responsibility and it is greater than 50% while level 3 is implicitly assuming human responsibility.
Now it's possible that different people have different interpretations of the phrase "is causing", but to me it implies it is the major component, i.e. > 50%, and the authors of 97.2% of the papers with a position on AGW responded to the proposition that human activity is causing global warming by saying their paper endorsed that proposition, either by explicity quantifying the degree of human involvement, by explicitly stating that humans are causing global warming, or by implying that humans are causing global warming.
If they felt their paper disagreed with that proposition, then levels 5, 6, and 7 were available for them to show how it expressed that disagreement.
Using the search facility on TCP for papers on "downscaling" gives
0 papers that explicity endorses and quantifies AGW as 50+%
6 that explicitly endorses but does not quantify or minimise
35 that implicitly endorses but does not minimise
46 that take no position
0 that implicity minimise or reject AGW
0 that explicitly minimises or rejects AGW but does not quantify
0 that explicitly minimises/rejects AGW at less than 50%
0 that are undecided
Which is pretty much what you would expect if you knew that downscaling was an area of research in climate change that had relatively little to do with attribution, and that scientists tend only to draw conclusions on issues that are directly addressed by the paper. I suspect the paper I co-authored would have been rated as "no postion" or "implicitly endorses but does not minimise", and three of my co-authors are from the Climatic Research Unit at UEA. You have a mistaken view of the motivations of scientists, scientific publications are generally rather understated.
engineer,
What makes you think I took offence? Surprised, maybe, that people post without reading first, but not offended.
As I said in the earlier comment I pointed you to, there's nothing "special" about the 12,000 papers that were manually rated. They are simply what was left after applying the earlier filters. Manual rating was required to filter out the irrelevant papers from that set in order to arrive at what was actually desired, namely, the set of papers that were relevant to the question at hand, which was to determine the percentage of papers in the scientific literature that endorsed the consensus position that "human activity is causing global warming" vs the percentage of papers in said literature that rejected that position. The size of that set of papers with respect to the size of set of papers that required manual rating is mildly interesting but irrelevant. After all, with sufficient effort, they could have simply manually checked all scientific papers during that period, which should not have changed the relevant percentages but which would have reduced the percentages you're interested in to minuscule values. The purpose of the filtering was to make the problem tractable, that's all.
Note that I am not an author of the paper. I, like many others, participated in the online rating exercise announced here a few weeks ago to get a taste of what was involved. I suggest you have a go, because by doing so you'll quickly realise the true nature of the papers that end up being rated neutral and why they don't make statements about the cause of global warming, contrary to your current expectations, but you'll need to try the more recently announced exercise instead, which appears to be very similar, because the former has already closed.
@ Kevin C 165,
Unless you know that the first 100 are representative of the 300, you can't make any comment on the 300. You can't assume anything. For all you know in your example is that right handed pirates hear better, so came forth with their reply before the left handed pirates did, or conversely, the left handed pirates hear better and come forward right away, and there is only three of them in total.
I just attended a talk by James Hansen at NASA Ames Research Center. One of his main points right up front is that a big part of the problem is the large gap between climate scientists' knowledge and public perception of that knowledge.
The best analogy I could think of to describe the current situation of the large gap between the publics' knowledge and published climate scientists is the knowledge gap between the passengers of a very large airliner and the flight crew.
Would you board an aircraft where the passengers have a vote on what control inputs should be used at all times. These votes would be open to the most shrill passengers that made the most noise without any knowledge or evidence. Even if the full instrument panel was displayed on all the screens in the passenger compartment the passengers do not even have the slightest idea of what they all mean. The self appointed 'knowledgeable' passengers who are not trained pilots are a cacophony of conflicting interpretations of how to fly the aircraft. They cannot even agree amongst themselves how their 'expert' opinions should be implemented.
This is the situation Space Ship Earth finds itself in.
The first aircraft to fly from England to Australia was a Vickers Vimy Bomber flown by Keith and Ross Smith in 1918. Their call sign was GEAOU. Both Keith and Ross (not related) jokingly said it stood for God 'elp all of us! Bert
Jason,
we are agreed that different interpretations are possible. This is a weakness of the consensus statement sent in the email, and the ratings scheme. The only way I can think to test for differences is to email all the Authors who rated to clarify that they though was meant by options 2 and 3. A subset of respondants should give a clue.
Because if a good number of respondants interpreted as I, Zeke Hausfather and a number of other reasonable commenters did, then the bar for them was much lower than yours/Cook et al, and this would significantly weaken the results. For example, Cook et al's claim that their ratings were more conservative than the original Authors' would be undermined.
Consider Dana Nuticelli's comment at another blog on the Cook et al ratings as he sees it.
http://ourchangingclimate.wordpress.com/2013/05/17/consensus-behind-the-numbers/#comment-18747
Huh? If a paper (abstract) simply said anthro GHGs are causing global warming (with no quantification), that went into the endorsement category. It seems that the raters (or Dana at least) assumes that any paper that endorses the notion of GHGs causing global warming, perforce endorses a >50% human contribution.
barry,
I think you (and others I saw at the earlier link you posted) are getting hung up on the "> 50%" figure, when that is not the outcome of the survey, it was a tool for categorising a certain subset of papers.
The title of this post says:
Skeptical Science Study Finds 97% Consensus on Human-Caused Global Warming in the Peer-Reviewed Literature
The first sentence is:
A new survey of over 12,000 peer-reviewed climate science papers by our citizen science team at Skeptical Science has found a 97% consensus among papers taking a position on the cause of global warming in the peer-reviewed literature that humans are responsible.
The graphic says:
97% of climate papers stating a position on human-caused global warming agree global warming is happening and we are the cause.
The email sent to authors asked them to state whether their paper endorsed the proposition:
that human activity is causing global warming
Every one of them is consistent. Not one of them mentions the >50% figure. Why? Because the point of the exercise is whether global warming is happening and we are the cause.
The only reason categories 1 and 7 exist is because some papers actually quantify the various causes, and so in papers that quantify the human contribution, the rule was > 50% counts as an "endorse" while < 50% counts as a "reject". That's all.
If the graphic said "97% of climate papers state that humans are responsible for > 50% of global warming" then you'd have a point, but it doesn't. As I said, the numbers 1..7 are not meant to be interpreted as a confidence levels, or degrees of agreement with the proposition, but merely to categorise the manner in which the agreement or rejection was expressed in the paper. The fact that the authors of 97.2% of the papers that stated a position claimed that their paper agreed with the proposition and the reviewers of the abstracts found that 97.1% of those that stated a position agreed with the proposition is very strong evidence to me that they used the same interpretation.
I don't agree that this should be seen merely as a matter of opinion or interpretation. The email is very clear. The paper is also very clear. The only thing I would change is the word "level" rather than "category" since that is apparently confusing some people.
Dana's comment is also saying the same thing.
Jason, Dana said:
If that was the basis (and you, argue that ratings 5, 6 and 7 should be viewed as rejection of AGW at >50%, implying, in a symmetrical ratings scheme, that 1, 2 and 3 are endorsement at>50% (implied or explicit)), then I don't see much wriggle room.
Can you clearly state in a sentence, if you think ratings 2 and 3 refer to an endorsement at >50% level, or only that anthropogenic warming is signficant in a qualitative sense. Just something clear and simple.
It would be good to have clear statements from others. I'm pretty sure Tom Curits was arguing that 2 and 3 are >50% endorsements.
If you read the introduction to Cook et al, this is one statement of consensus:
It is confusing in the paper, as other statements on what the consensus is are less exact, as in the abstract.
It is confusing in discussions about it because there is little agreement on what the ratings reflect. This disagreement does not fall on ideological lines (regulars at Lucia's are arguing about them, too).
The problem is that the definitions are unclear and open to misinterpretation. It doesn't matter that results are so similar if there is ambiguity in the methodology. Indeed, if Cook et al have a unified understanding that is different to interpretations made by original Authors, then that is a problem, weakening a number of key points in the study, namely to do with corroborating the impartiality/conservatism of Cook et al. The close matchup of results may be a result of these extraneous factors due to the ambiguity of definitions in the ratings schema.
It can be argued that 'primary cause' or 'dominant cause' of global warming could mean as little as 33%, if other contributing factors are each not greater than 33%. Is this what 2 and 3 refer to?
It's simply unclear. I'd like to know in simple terms how others view the ratings. When I took the survey, I only applied >50% to 1 and 7, and the rest were qualitative. If Cook et al rated all but option 4 as an endorsement/rejection at 50% human contribution, then they rated differently to me, and possibly to many of the responding Authors.
barry - In 2001 the IPCC consensus states that:
In 2007, the IPCC stated:
And also:
Given that as the widely understood "consensus", I find claims of categories 2 and 3 not supporting a majority factor for human causes to be simply ridiculous.
And yet, KR, the ridiculous interpretation is how many reasonable people have taken 2 and 3.
Can you explain why abstracts saying "human greenhouse gas emissions are causing global warming" means that they are, perforce, positing >50% human influence? The quote I've just given is from Dana, one of the authors of Cook et al, and that unquantified statement was suffcient for the abstract to be rated as endorsing.
(the quote is linked a few posts upthread)
barry,
Let's consider the original authors' ratings for the moment.
The authors were sent an email. That email quite clearly said, as you have already quoted yourself, "The second drop down indicates the level of endorsement for the proposition that human activity (i.e., anthropogenic greenhouse gases) is causing global warming (e.g. the increase in temperature)." They are not being asked to quantify the human contribution, nor state their certainty of the human contribution, but merely to say whether their paper endorses that proposition, rejects that proposition, or doesn't address or mention the issue of what's causing global warming. The very next statement says "we are not asking about your personal opinion but whether each specific paper endorses or rejects (whether explicitly or implicitly) that humans cause global warming". Then the seven "levels" are stated, and, sure enough, the only difference between 1, 2, and 3 is the manner in which that endorsement is manifested in the paper (i.e. implicitly or explicitly, and if explicit, with or without quantification), and the only difference between 5, 6, and 7 is the manner in which that rejection is manifested in the paper, in exactly the same way as the endorsement case.
Note, for example, that a paper classified as "level 1" could easily be less "alarmist" than a paper classified as "level 2" or "level 3". A level 1 paper is likely to be an attribution study whereas a "level 3" could be an impacts study and, as such, could well be far more alarming.
As I mentioned in an earlier comment, someone else at Lucia's managed to confuse the levels with a measure of climate sensitivity, which is nonsense. There is only one proposition being put, and that is whether humans are causing global warming or not.
Note that it's really quite a strong statement as well. There's no wriggle room here. If someone wrote a paper that accepts that greenhouse gasses cause global warming, and that humans are responsible for GHG emissions, but that e.g. natural variability had a larger role to play in the warming to date than humanity, their paper would be classified as rejecting the proposition.
Now for Cook et al. In the introduction to the paper they clearly state that
We examined a large sample of the scientific literature on global CC, published over a 21 year period, in order to determine the level of scientific consensus that human activity is very likely causing most of the current GW (anthropogenic global warming, or AGW).
This is simply a restatement of the IPCC consensus statement, quoted by KR, and it doesn't matter if other restatements of it elsewhere in the paper are less precise because this is the proposition they are evaluating.
"Most" translates into "> 50%" when expressed numerically and answers your question:
It can be argued that 'primary cause' or 'dominant cause' of global warming could mean as little as 33%, if other contributing factors are each not greater than 33%. Is this what 2 and 3 refer to?
No. If a paper quantified the human contribution to global warming at 33% then regardless of other contributing factors it quite clearly would have been categorised as "level 7": "paper explicitly states that humans are causing less than half of global warming".
There is no room for interpretation here. Level 1's "Explicitly states that humans are the primary cause of recent global warming" has to be read in the context of Level 7's "Explicitly states that humans are causing less than half of global warming", which rules out any possibility other than ">= 50%" for Level 1.
Likewise, levels 2 and 3 are symmetric with levels 6 and 5, respectively.
barry,
Can you explain why abstracts saying "human greenhouse gas emissions are causing global warming" means that they are, perforce, positing >50% human influence? The quote I've just given is from Dana, one of the authors of Cook et al, and that unquantified statement was suffcient for the abstract to be rated as endorsing.
Because the hypothetical abstract says that human greenhouse gas emissions are causing global warming? Just because the statement omits a number doesn't mean it isn't endorsing the proposition, which didn't include a number anyway.
As I've already pointed out, the graphic makes the statement that "97% of climate papers stating a position on human-caused global warming agree global warming is happening and we are the cause". How can you argue that a paper that says exactly the same thing — that human greenhouse gas emissions are causing global warming — should not be categorised as endorsing that position?
And again, I'll point out that the original authors, given the explicit request to state whether their paper endorses the proposition, rejects the proposition, or doesn't address it, gave the same percentage of endorsements and rejections as Cook's team did, even while finding that many papers that Cook's team relegated to "neutral" on reading the abstracts alone actually did make a statement when the whole paper was taking into account.
Jason, I'll point out again that the match could still be a coincidence if the Authors interpretation of the ratings system for their papers, was different than Cook et al for the abstracts to those papers. Post hoc reasoning is not acceptable.
You ask,
[A] implies human influence as the dominant - in fact the ONLY cause.
[B] can be taken to mean that anthro influence is a contributing factor, but not necessarily dominant
They are different.
Whatever interpretation is taken, there is no doubt that the consensus is that human activity is causing at least some global warming.
If the consensus statement being tested by 1, 2 and 3 (and the rest) is meant to be whether human contribution is >50%, then I think the results are flawed, as this proposition is not explicit enough in the consensus statement emailed to Authros, and the rating system. It is also confusing in the paper, but I now strongly believe that this was indeed, the intention of Cook et al. (Why are they not commenting here?)
Perhaps participants here could select which of these statements is most accurate.
"97% of climate papers stating a position on human-caused global warming agree that human influence on global warming over the last 50 years is...
a) >50%
b) dominant
c) significant
d) a contributing factor
I think either of those are valid for rating options 2 and 3, depending on how the email is interpreted.
My own take doing the (public) survey was c).
To clarify, c) - significant influence - was what I took to be the criterion for rating options 2 and 3 when I participated in the public survey.
But another person might have rated those with a lower (d) or higher (a,b) bar.
Lack of clear definitions is a problem for the paper as I've argued upthread.
If Zeke was here, I think he'd say c) and/or d).
What do others think?
Next we'll be arguing what the meaning of "is" is!
barry, the authors were asked to state whether or not their papers endorsed the proposition that human activity is causing global warming. If they felt that their paper either implied or stated that human activity was a contributing factor but not the primary cause then they could have categorised their paper as level 5, 6, or 7, depending on how it was presented. (Remember, level 5 includes any proposition that something other than humans was the main cause, and level 7 includes any quantification less than 50%.)
I said that the statement Cook et al were testing was very strong, so let's look at what you claim the "consensus" is: "that human activity is causing at least some global warming". Papers classified by Cook et al as levels 1-3 would obviously also agree with your claim. But so would papers classified by Cook et al as level 5, some of the papers classified by Cook et al as level 6, and any of the papers classified by Cook et al as level 7 that had a percentage greater than 0.
In other words, the only papers that Cook et al counted as rejecting their proposition that you would also claim reject your rendition of the consensus are those in level 6 that explicitly reject that humans are causing global warming and those in level 7 that state humans are causing 0% or less of global warming.
Clearly, Cook et al's statement is a lot stronger than yours, as it filters out many possible papers that you would consider endorsing your consensus. I would guess that very close to 100% of the papers would pass your test.
Finally, to point out that the authors of the original papers, when asked if their papers endorsed the claim that human activity is causing global warming, resulted in the same percentage of endorsement as Cook et al did by examing the abstracts alone, is not "post-hoc reasoning", it's evidence that the same criteria were applied, because it would be absolutely staggering for both groups to have arrived at the same percentage by coincidence, especially when the original authors added a large number of extra papers to the mix that Cook et al were forced to assess as "neutral" based on the abstracts alone.
It also means that the abstract examination process provided an unbiased estimate of what the full paper would actually say.
I've been playing with the search tool to tabulate the results; I managed to collect results for 11,942 papers using a space as the search term; that's two fewer than Cook et al. Curiously, I ended up with exactly one extra paper in levels 1-3, two fewer in level 4, and one missing in levels 5-7. Could have been a typo when I was entering the numbers into the spreadsheet, although I just double-checked level 4 and got exacly the same result.
Anyway, of interest to this discussion is the breakdown between papers that quantify the human contribution to global warming as >= 50% and papers that quantify the human contribution to global warming as < 50% (i.e. levels 1 and 7), since there is no interpretation required for those. The former represent 88% of all papers that quantify the human contribution to global warming (64 of 73). A small difference to the overall percentage, but the level of endorsement still overwhelming, and due to the relatively small sample size, a small difference is to be expected. (I would also not be surprised if papers purporting to refute the consensus would do so with quantification, so this group is perhaps more likely to include a higher percentage of contrarian papers.)
For the papers that make explicit statements about causation without quantification, those that explicitly state humans are causing global warming represent 98.4% of the total (923 of 938).
For the papers that imply the impact humans are having, those that imply humans are causing global warming represent 98.2% (2910 of 2963).
My figure for the overall endorsement percentage is 98.06%. Not sure why the paper gives a lower figure.
In any case, no matter how the results are spun, or words are interpreted, it is pretty clear that the literature falls heavily on one side. I think anybody who seriously wants to challenge the results really needs to show papers that were mis-categorised; all the abstracts are available together with the category that was applied, so nothing is hidden, and if someone wants to apply their own "interpretation" to the rating system they have the means to do so.
Perhaps, to make the problem more tractable, they could start by checking for papers that they know disagree with the consensus and make sure those show up in the right place.
Can we please stop talking about consensus. Science isn't about a show of hands. There used to be consensus that "bleeding" a patient solved most medical problems. So called consensus has proven to be wrong too many times in the past. Let's stick to scientific evidence.
barry - "And yet, KR, the ridiculous interpretation is how many reasonable people have taken 2 and 3."
Reasonable people? Perhaps... But many of the people raising this issue (this obfuscation, in my point of view) are not climate scientists, and are not as aware of the IPCC reports. Or at all fond of of the IPCC and its conclusions, for that matter (cf motivated reasoning).
"Can you explain why abstracts saying "human greenhouse gas emissions are causing global warming" means that they are, perforce, positing >50% human influence?"
As I pointed out above, because the category titles are part of the description as well, and because, quite frankly, anyone familiar with the science knows that AGW means human caused global warming:
Jason,
I'm making no claim as to what the consensus statement is meant to be.
I agree. But if Authors rating at 2 and 3 (which comprise a huge bulk of the endorsement ratings) take that to mean anything between, say, 'some' influence and >50%, and Cook et al take it to mean >50%, then the rating criterion is different and this may signficantly affect the comparitive results.
Would I be correct in assuming you would say that options 2 and 3 rate the human influence on global warming as dominant (b)?
I'm hoping to garner clear responses to see if there are different interpretations by commenters here. Tom Curtis began as an author on Cook et al, but declined participation after a while. Judging by comments he has made at Lucia's he is saying that ratings 2 and 3 refer to >50% influence. Eg,
http://rankexploits.com/musings/2013/on-the-consensus/#comment-113388
You write;
Apart from 1 and 7, none of the ratings are quantified. The descriptors are "endorses" and "minimises" AGW. These are qualitative statements, and that was how I read them. That is also how Zeke Hausfather read them.
http://rankexploits.com/musings/2013/on-the-consensus/#comment-113263
That 2, 3, 5 and 6 relate to >/< 50% human contribution may be inferred in context, but other inference is also possible.
My point is, if reasonable people disagree on the ratings criterion (and the 2 I've cited are 'friendlies', there is yet more disagreement between other parties), then original Authors may have had different interpretations, and this may well undermine the comparitive results that are a strong corroborative feature of the paper. The similarity of results could be a fluke.
The only way to test that, that I can think of, is by asking the original Authors who rated their own papers what they assumed the criterion was for 2 and 3 (and 5 and 6).
If the point of the paper is to demonstrate there is a consensus that more GHGs in the atmosphere should cause some warming, then that is not as impactful as endorsing the IPCC statement. It's a much lower bar with a much smaller target audience. None of the contrarian climate scientsts dispute that, and neither do most prominent skeptics (including Anthony Watts, for example) and most of their followers.
The basic message is fine - and the effort has been successful on that regard. I'm discussing the academic merit of the Cook et al study.
barry,
I'm making no claim as to what the consensus statement is meant to be.
You said "there is no doubt that the consensus is that human activity is causing at least some global warming". Cook et al's results are far stronger than that, as I already explained.
I don't know how many times I can keep saying this; the original authors were asked whether their papers endorsed AGW. The results are being reported as the percentage of papers that endorse AGW. There is no discrepancy. What the general public wants to know is "is human activity causing global warming?". That's exactly the statement that the authors of 97.2% of the papers that expressed an opinion on the matter said their paper endorsed. QED.
[JH] Be careful of excessive repitition.
Jason said, "Next we'll be arguing what the meaning of "is" is!"
Exactly. At this point Cook et al 2013 is part of the published research on this matter. If there are people like Lucia and others who wish to challenge the findings, they should do so by the way of publishing their own paper.
They are more than welcome to craft their own methodology to test the level of consensus on AGW. But, like with the hockey stick, I think the results they would get would go against the conclusions they want to see, and to get the conclusions they'd prefer would require contortions that would not pass peer review.
@Barry #189:
You state: I'm discussing the academic merit of the Cook et al study.
What exactly do you mean when you use the phrase, "academic merit"?
rhjames:
Claims identical to yours have been examined before and rightly dismissed, for three reasons.
First, most orthodox or consensus positions before the scientific revolutions in various disciplines were not based on anything like as rigorous the methodologies used to generate consensus positions in the sciences today, and are an inappropriate point of comparison. Who cares whether or not there was a consensus about bloodletting in the past? The consensus about AGW is comparable to the consensus of other contemporary scientific topics: quantum mechanics, relativity, and the like. (*)
Second, the consensus of experts follows from the preponderance (or, if you will, the consensus) of the evidence, a point that has been raised on several occasions on this thread and any other occasion where the scientific consensus has been discussed.
Third, research shows that the public perception of the scientific consensus is an important component of public advocacy for action to reduce emissions and mitigate global warming. So it is in fact critical, if we want to avoid the worst consequences of rapid global warming, to spread the word about the consensus.
(*) In point of fact I have a hard time thinking of any case where a scientific consensus, in the modern sense, of over 90% of scientists has arisen that has actually been overturned, with the possible exception of what caused gastric ulcers. In past cases either the consensus was non-scientific, or there was no consensus position to speak of.
rhjames said... "Let's stick to scientific evidence."
You seem to be operating under the erroneous assumption that Cook13 is a survey of scientists (a "show of hands"). It is not. It is a survey of the published research.
It's entirely likely that there is research within the survey that reflects different positions on papers coming from any one scientist. A researcher that has published a large body of research could potentially have papers that fall into each of the 7 endorsement categories. Certainly most of the researchers who have multiple papers in the study have them falling into at least two or more of the categories.
So, really, the opinions of the scientists themselves matter little. What matters is what their data show.
I have to say, one of the most compelling aspects of Cook13 is that the resulting consensus figures for the SkS rated papers almost precisely match the consensus figures coming out of the scientists' self-ratings. (97.1% vs 97.2% respectively)
If there was ever a great example of self-skepticism, this was it. John Cook made sure that we tested our own biases here at SkS against the evaluation of the scientists themselves. And not just a few cherry picked scientists. We tested against a very large number of scientists.
rhJames - firstly, a consensus does exist. Secondly, while a consensus is not proof of a theory, it is the only reasonable basis for public policy so it is important to know what it is.
"Lets stick to the scientific evidence" _ well I wish deniers would but they instead prefer blog "science", cherry picking and misrepresentation. Cook13 is effectively a survey of the published scientific evidence.
barry,
Rather than going round and round in circles arguing over definitions, let's make this concrete:
Earlier you claimed that there is a difference in meaning between the wording in the graphic and the wording in Dana's example of a paper that would be classified as endorsing the consensus ("we are the cause" vs "we are causing").
I propose a test: Can you give any examples of abstracts that were rated as level 2 or level 3 that you feel do not endorse the statement in the graphic?
If your argument is correct, there should be papers that you feel do not support the claim and based on the number of them we can ascertain the impact that would have on the results.
Note that unless you're going to do an exhaustive search, you need to count how many papers you looked at as well as how many examples you found. This is so we can get a percentage that can be used to estimate the impact. You can also propose what you view as the "correct" classification for the examples you find.
Until then, this argument is merely academic.
I'm having a problem interpreting this study. The banner conclusion is that "among abstracts expressing a position on AGW, 97.1% endorsed the consensus position that humans are causing global warming." But in the Results section it states: "To simplify the analysis, ratings were consolidated into three groups: endorsements (including implicit and explicit; categories 1–3 in table 2)..." This is where I'm experiencing a disconnect. Categories 2 and 3 are too ambiguous - as defined in table 2 - to equate to the consensus that humans are not only a cause of industrial era global warming but the dominant cause since the middle of the last century (at least). Am I not reading that right? And if so, shouldn't only those abstracts that take an unambiguous stand on the consensus of dominant human causation be counted and the others excluded in the same way that abstracts that take no stand at all were excluded?
s_gordon_g... Instead of trying to over interpret the exact wording, take a step backward and look at big picture.
~97% of the research supports AGW.
~3% of the research rejects AGW.
The way you're approaching it, you're completely missing the forest for the trees. This is a common "skeptic" tactic when faced with data they don't like.
John Hartz,
Quality of scholarship..