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Guest post: scrutinising the 31,000 scientists in the OISM Petition Project

Posted on 11 March 2010 by angliss

In early 2008, the Oregon Institute of Science and Medicine (OISM) published their Petition Project, a list of names from people who all claimed to be scientists and who rejected the science behind the theory of anthropogenic (human-caused) global warming (AGW). This was an attempt to by the OISM to claim that there were far more scientists opposing AGW theory than there are supporting it. This so-called petition took on special importance coming after the release of the Intergovernmental Panel on Climate Change’s Fourth Assessment Report, and specifically the Working Group 1 (WG1) report on the science and attribution of climate change to human civilization.

The WG1 report was authored and reviewed by approximately 2000 scientists with varying expertise in climate and related fields, and so having a list of over 30,000 scientists that rejected the WG1’s conclusions was a powerful meme that AGW skeptics and deniers could use to cast doubt on the IPCC’s conclusions and, indirectly, on the entire theory of climate disruption. And in fact, this meme has become widespread in both legacy and new media today.

It is also false.

According to the Petition Project “qualifications” page, “Signatories are approved for inclusion in the Petition Project list if they have obtained formal educational degrees at the level of Bachelor of Science or higher in appropriate scientific fields.” The fields that are considered “appropriate” by the OISM are as follows:

  • Atmosphere, Earth, and Environment fields: atmospheric science, climatology, meteorology, astronomy, astrophysics, earth science, geochemistry, geology, geophysics, geoscience, hydrology, environmental engineering, environmental science, forestry, oceanography
  • Computers and Math: computer science, mathematics, statistics
  • Physics and Aerospace: physics, nuclear engineering, mechanical engineering, aerospace engineering
  • Chemistry: chemistry, chemical engineering
  • Biochemistry, Biology, and Agriculture: biochemistry, biophysics, biology, ecology, entomology, zoology, animal science, agricultural science, agricultural engineering, plant science, food science
  • Medicine: medical science, medicine
  • General Engineering and General Science: engineering, electrical engineering, metallurgy, general science

oismpet-smThe OISM’s qualifications for being a “scientist” are expansive, and as such there are a number of questions that have to be answered before we can take this list seriously. What expertise does a nuclear engineer or a medical doctor or a food scientist or mechanical engineer have that makes them qualified to have an informed opinion on the cause(s) of recent climate disruption? How many of these names are working climate scientists instead of science or math teachers or stay-at-home-mom’s with engineering degrees? How many of these people has actually published a peer-reviewed paper on climate? How many people took a look at the card that served as a “signature” (click on the image to see a larger version) and realized that they could lie about having a science degree and their deception would never be discovered?

At this point it’s literally impossible to know because the names and degrees on the list cannot be verified by anyone outside the OISM. We can only take the OISM’s word that they’re all real names, that all the degrees are correct, and so on. This does not stand up to the most basic tests of scientific credibility.

Unfortunately, the OISM’s list has had its credibility fabricated for it by individuals and groups as diverse as Steve Milloy of Fox News (see this link for a S&R investigation into the background and tactics of Steve Milloy), L. Brent Bozell of conservative “news” site Newsbusters and founder of the conservative Media Research Center, Benita M. Dodd of the Georgia Public Policy Foundation, the libertarian/conservative site American Thinker (a site that has regularly failed to fact-check their AGW posts), conservative commentator Deroy Murdock (who works on Project 21 with the wife of one of Steve Milloy’s long-time associates), RightSideNews, Dakota Voice, Dennis T. Avery of the Hudson Institute, Lawrence Solomon of the Financial Post, Michelle Malkin, and the Competitive Enterprise Institute, to name just a few of the better known. As a result, the OISM’s petition has been elevated to a level of credibility that is arguably undeserved.

While it’s not possible to test the validity of OISM list directly, it is possible to test the conclusions that have been drawn from the OISM list. Specifically, we can test what percentage the 30,000 “scientists” listed on the OISM petition represent when compared to the total number of scientists in the U.S. And we can then compare that to the percentage represented by the 2000 IPCC AR4 WG1-associated scientists as compared to the estimate number of U.S. climate-related scientists.

According to the OISM website, anyone with a Bachelor’s, Master’s, or Doctorate of Philosophy in a field related to physical sciences is qualified as a scientist. In addition, the OISM sent the petition cards pictured above only to individuals within the U.S. Based on this information, we can us the OISM’s own guidelines to determine how many scientists there are in the U.S. and what percentage of those scientists are represented by the OISM petition.

The U.S. Department of Education tracks the number of graduates from institutions of higher education every year, and has done so since either the 1950-51 or 1970-71 school years, depending on what specifically the Dept. of Ed. was interested in. This data was last updated in the Digest of Education Statistics: 2008. We’re specifically interested in the number of degrees that have been awarded in the various scientific disciplines as defined by the OISM in the list above. This information is available in the following tables within the 2008 Digest: 296, 298, 302, 304, 310, 311, and 312. Table 1 below show how many graduates there were in the various categories defined by the Dept. of Ed. since the 1970-71 school year (click on the image for a larger version). The numbers have been corrected to account for the fact that PhD’s will usually have MS degrees as well, and that both are preceded by BS degrees.

oismtable1-sm

As you can see, Table 1 shows that there were over 10.6 million science graduates as defined by the OISM since the 1970-71 school year. This is a conservative estimate as illustrated by the 242,000 graduates in biological and biomedical sciences from 1950-51 through 1969-70 alone, never mind the 166,000 engineering graduates, and so on. Many of these individuals are still alive today and would be considered scientists according to the OISM definition thereof.

The OISM website lists how many signatures they have for scientists in each of their categories. Given the number of graduates and the number of signatures claimed by the OISM, we can calculate the percentage of OISM-defined scientists who signed as referenced to the total. These results are shown in Table 2 below.

oismtable2-sm

In other words, the OISM signatories represent a small fraction (~0.3%) of all science graduates, even when we use the OISM’s own definition of a scientist.

However, as mentioned above, it’s entirely reasonable to ask whether a veterinarian or forestry manager or electrical engineer should qualify as a scientist. If we remove all the engineers, medical professionals, computer scientists, and mathematicians, then the 31,478 “scientists” turn into 13,245 actual scientists, as opposed to scientists according to the OISM’s expansive definition. Of course, not all of them are working in science, but since some medical professionals and statisticians do work in science, it’s still a reasonable quick estimate.

However, it’s not reasonable to expect that all of those actual scientists are working in climate sciences. Certainly the 39 climatologists, but after that, it gets much murkier. Most geologists don’t work as climate scientists, although some certainly do. Most meteorologists do weather forecasting, but understanding the weather is radically different than understanding climate. So we can’t be sure beyond the 39 climatologists, although we can reasonably assume that the number is far less than the 13,245 actual scientists claimed by the OISM.

13,245 scientists is only 0.1% of the scientists graduated in the U.S. since the 1970-71 school year.

We can, however, compare the number of atmospheric scientists, climagologists, ocean scientists, and meteorologists who signed this petition to the number of members of the various professional organizations. For example, the American Geophysical Union (AGU) has over 55,000 members, of which over 7,200 claim that atmospheric sciences is their primary field. The OISM claims 152 atmospheric scientists. Compared to the atmospheric scientist membership in the AGU, the OISM signatories are only 2.1%, and this estimate is high given the fact that the AGU does not claim all atmospheric scientists as members.

The AGU hydrology group has over 6,000 members who call hydrology their primary field. The OISM list has 22 names that claim to be hydrologists, or 0.4%.

The AGU ocean sciences group claims approximately 6,800 members. The OISM has 83 names, or 1.2%. And again, given that AGU membership is not required to be a practicing ocean scientists, this number is inflated.

The American Meteorological Society claims over 14,000 members and the OISM claims 341 meteorologists as petition signatories. That’s only 2.4%.

It’s clear that the OISM names don’t represent a significant number of scientists when compared to either the total number of science graduates in the U.S. or to the number of practicing scientists who work in likely relevant fields. But that’s not all.

Over recent years, various organizations have set out to estimate just how widespread the supposed “scientific consensus” on AGW actually is. Two recent efforts were conducted by the Statistical Assessment Service (STATS) at George Mason University and by the Pew Research Center for the People and the Press. The STATS survey found that 84% of climate scientists surveyed “personally believe human-induced warming is occurring” and that “[o]nly 5% believe that that human activity does not contribute to greenhouse warming.” The STATS survey involved a random sampling of “489 self-identified members of either the American Meteorological Society or the American Geophysical Union” and it has a theoretical sampling error of +/- 4%.

The Pew survey was taken in early 2009 and asked over 2000 members of the American Association for the Advancement of Science (AAAS) their opinion on various scientific issues, including climate disruption. 84% of AAAS respondents felt that “warming is due to human activity” compared to only 10% who felt that “warming is due to natural causes.” The AAAS has over 10 million members, and the results of the survey are statistically valid for the entire population with a theoretical sampling error of +/- 2.5%.

84% of 10 million scientist members of the AAAS is 8.4 million scientists who agree that climate disruption is human-caused. 84% of the climate scientists (conservatively just the members of the atmospheric science group of the AGU) is, conservatively, 6,000 scientists who have direct and expert knowledge of climate disruption. The 13,245 scientists and 152 possible climate scientists who signed the OISM petition represent a small minority of the totals.

The IPCC AR4 WG1 report was written and reviewed by approximately 2000 scientists. If we assume that the 20,000 AGU members who claim to be atmospheric scientists, ocean scientists, or hydrologists represent the pool of potential experts in climate science in the U.S., then approximately 10% of all climate scientists were directly involved in creating the over 1000 page report.

That compares to less than 1% of all OISM “scientists” who mailed a pre-printed postcard.

A more recent survey of earth scientists asked the question "Do you think human activity is a significant contributing factor in changing mean global temperatures?". 97.5% of climatologists who were actively publishing papers on climate change responded yes.(Doran 2009). What is most interesting about this study was that as the level of active research and specialization in climate science increases, so does agreement that humans are significantly changing global temperatures.


Figure 1: Response to the survey question "Do you think human activity is a significant contributing factor in changing mean global temperatures?" (Doran 2009) General public data come from a 2008 Gallup poll.

Ultimately, The OISM petition will continue to rear it’s ugly head until its fabricated credibility has been thoroughly demolished. Social conservatives and libertarians, each of which has their own ideological reasons to push the OISM petition, have been effective at keeping the “30,000 scientists reject warming chicken-littleism of IPCC” meme circulating throughout conservative media outlets, even as climate disruption-focused media have worked at limiting the damage from the OISM petition. But given the fact that the science supporting a dominantly anthropogenic cause for climate disruption is overwhelming, it’s only a matter of time before the OISM petition wilts in the heat.

Acknowledgements to Brian Angliss at Scholars and Rogues who guest wrote this post.

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Comments 51 to 100 out of 142:

  1. RE#31-Robhon I have to say I agree with you there. Performing a survey about which supposedly qualified person believes what is clearly not the best approach to bring prove anything to people. They can always be manipulated and misquoted by anyone in the media. “Science is not done by consensus” Policy is and requires weighting of the scientific evidence and action on it. RE#39,47-1077 What is your point? It is the science that should be judged not what peoples politics (assuming they live in a country with the freedom to choose) or lifestyles. Being forced to tick a box makes so many assumptions of people that it would be superfluous to the discussion of AGW. The whole discussion in the comments only highlights how poor such a survey would be.
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  2. "At this point it’s literally impossible to know because the names and degrees on the list cannot be verified by anyone outside the OISM." Why not? Has a list of the names not been published? Has the code by which the statistics were calculated not been published? Surely not!
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  3. "I am not the only one, for example Gavin Schmidt has a degree and a PhD in (applied) mathematics, I'm sure you wouldn't want to ignore his views. " To be clear, here are Gavin's credentials (from RC): "He received a BA (Hons) in Mathematics from Oxford University, a PhD in Applied Mathematics from University College London and was a NOAA Postdoctoral Fellow in Climate and Global Change Research. He serves on the CLIVAR/PAGES Intersection Panel and is an Associate Editor for the Journal of Climate. He was cited by Scientific American as one of the 50 Research Leaders of 2004, and has worked on Education and Outreach with the American Museum of Natural History, the College de France and the New York Academy of Sciences. He has over 60 peer-reviewed publications. " I think some are missing the main point of this post. No matter which criteria (debatable or not) one uses (stringent or lax), with any remotely reasonable criteria, the resulting numerator / denominator indicates a very small percentage of the scientific community are "skeptics". Those who move the goalposts with a "consensus isn't fact" argument are seemingly entirely oblivious to the main thesis put forth by Petition Project or Inhofe 700 style arguments (focusing on the numerator and ignore the denominator): that there is widespread dissent and a raging scientific debate over the key issues. It's an argument refuted nicely here, but one much of the public buys into.
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  4. yocta You seem to have it in for "old guys" remember Beethoven wrote his best music near the end of his life!
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  5. angliss & shdwsnlite I am quite used to having my professional opinions ignored by folk who know much les about my subject than I do. Sometimes it annoys me because I am human. However, I accept that people have the right to ignore me sometimes with serious consequences. Besides, on occasions, my profession (I mean psychiatry) has perpetrated some serious atrocities. Firthermore, I daily read reports by colleagues acting as 'hired guns' for insurance companies - a situation that my professional organisations has singularly failed to address. In the end, oversight by the courts (non-expert judges trained in law assisted by lawyers skilled in evaluating evcidence) has been the only corrective. So to get back on topic, climate scientists need to be subject to scrutiny just like everyone else.
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  6. chriscanaris... Being subjected to scrutiny is one thing. Being made the object of a witch hunt is completely another. Don't forget that people like Sen. Inhofe and others are literally trying to get people thrown in prison for practicing science that comes to a conclusions they object to politically.
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  7. robhon: Being subjected to scrutiny is one thing. Being made the object of a witch hunt is completely another. Well yes, sounds like psychiatry in the Soviet Union. Or the dominance of the Lysenko evolutionary paradigm in the Soviet Union. Or the rejection of Jewish science in Nazi Germany. Power tends to corrupt. Scientific bodies are not exempt from its corrupting influence, whether warmist or denialist. Again, one would hope that appropriate scrutiny by the Courts will protect.
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  8. Do we know how thoroughly OISM checked the respondents? Do all of the signatories exist, have the degree stated and are the actual person stated? Can we access the list still? Here id deltoids take http://scienceblogs.com/deltoid/2004/05/oregonpetition.php
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  9. I think the question of political affiliation is quite valid. Political influence and interference doesn't just apply to climate science, but many other scientific disciplines as well. Evolutionary Biology. Medical research. The list goes on. While it's true that not everyone can be lumped into the same camp and there are exceptions on both sides, there is a very clear pattern of how certain "sides" of politics treat scientific results that they don't like.
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  10. chriscanaris writes: However, I accept that people have the right to ignore me sometimes with serious consequences. Well, one could make the argument that there are some fields where the consequences of ignoring the experts are worse than others. In this particular field, our current policy of ignoring (or worse yet attacking) the experts is likely to lead to increased misery for future generations especially in countries more vulnerable to environmental change, and to a drastically increased rate of extinction worldwide. That said, I agree with you that no group or profession should exist without scrutiny and oversight. The question is, what are reasonable mechanisms for that kind of oversight? Scientists working in universities are subject to the review of their departmental colleagues, tenure committees, deans, external funding agencies, etc. Scientists working for the private sector or for government have their own versions of these. What's unique (and problematic) is the fact that the entire field of climate science is being attacked (not merely "scrutinized") by people who are actively hostile to the fundamental nature of the field as it exists today. I know there are those who are sincerely motivated by honest skepticism or curiosity. But it should be obvious to everyone by now that those voices are far outnumbered by others who are convinced that the whole climate science thing is a scam and everyone associated with it needs to be run out of town on a rail. Near the beginning of his talk at AGU last December, Richard Alley showed an email that was sent to the administration of his university: "Dr. Alley's work on ... CO2 levels in ice cores has confirmed that CO2 lags earth's temperature.... This one scientific fact alone proves that CO2 is not the cause of recent warming, yet ... Dr Alley continue[s] to mislead the scientific community and the general public about 'global warming' ... I await your prompt response confirming that an investigation into ... Dr Alley's activities will ... start prior to the end of this year. (His) crimes against the scientific community, [Pennsylvania State University], the citizens of this great country, and the citizens of the world are significant and must be dealt with severely to stop such shameful activities in the future." Now, the author of that email might be dismissed as one lone and unimportant individual ... except that over the past few years, and increasingly now, these kinds of attacks are becoming mainstreamed in the media and on the internet. Ultimately, in a democracy, "scrutiny" of every profession comes from the public at large. But most people have no direct experience or interactions with climate scientists, and so their views are shaped by the media, blogs, etc. In the current environment, a large and growing fraction of that "information environment" is being shaped by voices that have a gut-level hatred for the entire field and want to see it and everyone working in it utterly destroyed. That's rather different from the normal social oversight that most fields and professions are subject to
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  11. RE: 54 suibhne lol, It may seem that way but I don't. I have enormous respect for Paul Ehrlich and James Lovelock... i'm just thinking it just might take a generational change for skeptics to lose their weighting in the mainstream media.
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  12. While the number of scientist heads does not matter, the quality of the heads does. Let's consider a couple of prominent scientists who are much quoted on AGW issues. Take a look at Bob Watson defending the IPCC on TV: http://www.youtube.com/watch?v=Dzb8FljvGGI&feature=player_embedded Professor Robinson expresses complete certainty in a way that shows he does not understand what science is about. Watson could use a lesson in humility and clarity from a great scientist: “No amount of experimentation can ever prove me right; a single experiment can prove me wrong.” Albert Einstein Here is a quote from Kevin Trenberth (UCAR), October 12, 2009: "We can’t account for the lack of warming at the moment and it is a travesty that we can’t." This is in sharp contrast to Trenberth's public statements. Albert Einstein has something to say about integrity: "Whoever is careless with the truth in small matters cannot be trusted with important matters."
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    Response: "This is in sharp contrast to Trenberth's public statements"

    Actually, Trenberth's "can't account for the lack of warming" theme is expounded in frank, clear detail in the peer-reviewed paper  An imperative for climate change planning: tracking Earth's global energy (Trenberth 2009). This paper is the topic of the email where that quote is taken from. Unfortunately, most people fail to read the full email. Certainly very few people read the paper he was refering to. I would highly recommend reading the paper or at the very least, this summation of the paper and what Trenberth was getting at.
  13. gallopingcamel, once again you have used your perception of people's demeanor in TV appearances as "evidence" against the objective scientific evidence for anthropogenic climate change. That is inappropriate for this Skeptical Science site.
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  14. Tom Dayton (#5), consensus is unimportant in science. I cannot say it any better than the first Einstein quote in (#62). You might claim that there was consensus about the validity of Newton's "Laws of Motion" for almost 300 years until Einstein's theories of Relativity were published. (#63), demeanor is not the issue; it is what these scientists say that determines their credibility. John Cook, you do a good job defending Trenberth but I am unconvinced. On the very first page of the paper you cited, the author states: "Given that global warming is unequivocally happening". I agree that this is slightly better than Bob Watson who assures us that "climate change" is happening. He can hardly be wrong on that one!
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    Response: Trenberth has probably written as many papers as anyone on satellite data of outgoing and incoming radiation - if there was anyone who would know whether the global warming was happening (eg - that the planet is in positive energy imbalance), it would be Trenberth.
  15. gallopingcamel at 17:04 PM on 12 March, 2010 Several hundred words, chock-a-block with specific findings, supported by thirty references to other published works. Surely you did not stop after reading seven words of Trenberth's paper? What part of the rest of the paper leaves you unconvinced, specifically? What's your case?
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  16. The OISM is a barn in the middle of nowhere (see the picture on their home page) with a P.O. Box as its address and an important sounding domain name. It has no credibility as an institute, it happens to be in Oregon, thats all. I have a Physics degree, so I could declare myself to be the Californian Institute of Science and Medicine, put a sign on the side of my garage, list all my buddies that have degrees as members and start collecting online signatures, big deal... If you google "oism location" you will find that Google Maps will show you their barn on the map. I've driven in that area (from Crescent City to Grant's Pass) and it's rural mountains on the south border of Oregon. Google "oism debunk" for the many other times the list has been debunked, including attempts to identify anyone on the list. On Facebook 350.org currently has 77,935 fans http://www.facebook.com/350.org and you can verify that there are more real people, and I would claim more real scientists and real climate scientists on that list than the OISM list.
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  17. What people think is a fascinating subject, made even more interesting by what we think they know about what they think. And what preconceived ideas we think they have about the subject where we want to know what they think. Someone who's a practicing climate scientist in say paleogeology may happily accept a colleague's belief in the attribution of recent temperature changes to CO2. But does he/she understand the subject? Someone who's a practicing climate scientist in stratospheric chemistry may happily accept a colleague's belief in the rise or demise of the medieval warm period. But does he/she understand the subject? Slightly more than the average dentist I'm sure, but in the end, I doubt that any of this is going to convince anyone of anything. - Well, it will convince AGW adherents they are right. - And it will convince AGW skeptics they are right. I find it interesting that many climate scientists do have a concern over CO2 increasing even when (these ones) in their writing don't have such strong conviction about the attribution or forecasts. It makes me think. But that's because I've read their work. If I tell someone else I've read it.. The argument about how many climate scientists buy into something only helps if people feel a trust for climate scientists. And how insignificant the non-climate scientists scientists are only helps if people feel a trust for and resonance with climate scientists Otherwise, the numbers and graphs just seem like fuel for the climate wars.
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  18. Interesting. No-one seems to have commented on, or noticed, my post #24. There has been the usual analysis of the validity of the signatures, their qualifications, how many are Ginger Spice or Donald Duck, how many legitimate scientists signed the petition in comparison to the total number in the US etc etc. These have all been endlessly done to death, yet arguments like these are not going to make a dent in the petition's credibility amongst the general public. They haven't so far, and they probably never will. There are probably now more members of the general public who think that a huge number of scientists, much larger than the IPCC's, disagree with the basic climate science that there ever were. Trying to use the arguments above to destroy the credibility of the petition is a waste of time. My post #24 showed that it is the wording of the petition itself that needs to be consistently, loudly and powerfully attacked. If you actually read the words of the petition (mostly the second paragraph) you should be able to see that even if ALL the signatories had been fully conversant with climate science - understood that radiation imbalance due to increasing CO2 was a major cause; accepted that the globe is definitely warming and that we're mostly responsible - they could still legitimately sign it with a clear conscience, knowing that they had signed up to a scientifically valid statement. READ THE WORDS. There are elements of the first paragraph that are dubious and almost certainly wrong (though not 100% certain) but a casual, and still scientifically knowledgeable, reader could still have signed on the basis that they couldn't agree with all of the petition statement but that they did agree with the most important bit which states that there is no absolute proof that our emissions will lead to catastrophic disruption of Earth's climate - which everyone here should acknowledge is a true statement, if they understand the philosophy behind speaking in a genuinely scientific way at all. Of course, if they had read the accompanying "fake scientific" paper, they would have realised how they were being manipulated to create a piece of propaganda but like most petitions, most would not have researched it deeply. Shine a huge searchlight on the wording of the petition. Give up on the "Ginger Spice/people with inappropriate degrees who don't understand climate science" meme. Tell the public that the petition was designed to sucker real scientists into signing in order to subsequently exploit widespread general ignorance about the philosophy behind "measured uncertainty" in scientific statements, to sway the minds of the public. All those behind the denialist/inactivist/"sceptic" industry care about is increasing the numbers of potentially voting people who give them credence.
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  19. gallopingcamel, let's perform a little thought experiment. Imagine that someone waded through all of your posts and emails, pulled out nineteen words, and used them to claim that you believed X when you actually believe the opposite of X. Then, further imagine that you repeatedly explained that this was wrong, and asked that person to stop misrepresenting you. But instead of politely complying, that person continued to twist your words and claim that you believed something which you clearly do not. People have been told repeatedly here that the way you are using the "travesty" quote is completely wrong. John has some nice posts about this (1, 2) but it's also important to hear how Dr Trenberth himself feels about having his words twisted: ---------------- "Two Sundays in a row ill-informed columns about carbon dioxide and climate have appeared in the Camera. The first by Bob Greenlee (Jan. 3) and the second by Charlie Danaher (Jan. 10). Both misrepresent me and my work, and in particular, quote from one of my e-mails that was illegally stolen: 'The fact is that we can't account for the lack of warming at the moment and it is a travesty that we can't.' "The quote has been taken out of context. It relates to our ability to track energy flow through the climate system. We can do this very well from 1992 to 2003, when large warming occurred, but not from 2004 to 2008. The quote refers to our observation system which is inadequate to observe Earth's energy flows at the accuracy needed to understand small fluctuations in climate; it does not mean there is no global warming, as is often interpreted by the likes of Danaher. What [it] does mean is that our observing system is not adequate to fully track the energy in ways that allow us to understand and make best statements about the effects of natural climate variability: the La Niña of 2007-2008, and the current El Niño, for instance. "It is absolutely certain that carbon dioxide is a greenhouse gas and produces warming, despite Danaher's wishes. Without carbon dioxide and other greenhouse gases, Earth's surface would be some 32 degrees Fahrenheit colder than it is now. Increased carbon dioxide will increase this warming effect, and both theory and observations are consistent with this fact. The evidence of this happening is widespread and abundant, so that the Intergovernmental Panel on Climate Change (IPCC) in 2007 was able to state with unanimous agreement from all of over 100 countries that global warming is unequivocal. But global warming does not stop weather from happening, and cold outbreaks continue and are fully expected. It does not stop winter. And it does not stop La Niña from happening and setting up unusually cold regional patterns of weather across the United States and other parts of the world that last a year or two. "To misunderstand the role of weather and natural climate variability the way it is being done is to undermine much-needed actions in limiting carbon dioxide emissions. Global warming is happening. It will continue to happen and the way we are going it will jeopardize the very nature of climate on planet Earth some decades from now. Because of the long lifetime of carbon dioxide, by the time it is so obvious to everyone, it will be far too late to do anything about it. "Americans should be outraged that the Chinese are putting huge amounts of carbon dioxide into the atmosphere, and changing our climate! But by the same token, the Chinese should be outraged that the United States is putting nearly as much into the atmosphere, and historically a whole lot more than any other country, and changing their climate. We try to outdo each other in mutual self-destruction! "Putting a price on carbon dioxide emissions is an essential first step to responsible management of our planet. The United States needs to show leadership on this critical environmental issue." ---------------- That is what Dr Trenberth believes. As a graduate student, I had to work through the 800 pages of his textbook Climate System Modeling, so I'm more than willing to accept that he knows far more about the Earth's climate than I ever will. But even if you think Trenberth is wrong about CO2 and wrong about global warming, that does not justify your allegations that he is being dishonest about his beliefs. It is acceptable to argue that Trenberth's claims about climate science are wrong. It is morally unacceptable to argue that Trenberth doesn't genuinely believe his own statements. The very first item in the Comments Policy on this site says "No accusations of deception. Any accusations of deception, dishonesty or corruption will be deleted. This applies to both sides. Stick to the science. You may criticise a person's methods but not their motives." This isn't my site, but I would have to imagine that after reading his own words on the subject, you would drop the whole "travesty" argument and give Dr Trenberth the courtesy of respecting his statement about what his own opinions are. I apologize for the length of this comment.
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  20. The grand pooh-bah of the IPCC (Pachauri) is a railway engineer. If he is qualified to lead the IPCC climate effort, then anyone with a scientific or engineering degree is qualified to pass judgement. I find it completely astonishing that this guest post omits this interesting fact. (And don't bother trying to weasal out of this, there is no shortage of qualified climate scientists available for the post.) But I digress. The petition project is "unscientific" from the get go. And only has legs because AGW enthusiasts constantly harp on "consensus" and the thousands of scientists that endorse AGW. Given this petition project is completely flakey from the get go, I don't know why anyone bothers to spend time refuting it.
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  21. oracle2world, Pachauri was elected as Chair of a UN scientifc intergovernmental panel (IPCC) because he had been a Director/Governor/Executive/Adviser of many Academic/Scientific/Industrial bodies (and, previously, one of the Vice-Chairs of the IPCC); and because the US didn't like the previous Chair - Pachauri was more acceptable, I suppose, because of his industry and oil links. He is 'qualified to lead', because of his previous experience; he doesn't 'pass judgement' : he represents what the IPCC Panel determines.
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  22. greendirectionconsulting (#68) - I noticed, but didn't feel it necessary to comment. You're right, and that's an important part of the OISM story that should be added to this site's counterargument on this (which is, at present, a direct copy of this guest post).
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  23. Ned... Brilliant post regarding Trenberth. Excellent.
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  24. oracle2world... I think we spend time refuting it because it is so effectively used by tabloid media as "proof" that "most scientist" don't believe in AGW. Just look at the polls regarding global warming over the past few years. We are currently losing the battle to express to the world (or at least Americans) that this is real. http://www.gallup.com/poll/126560/Americans-Global-Warming-Concerns-Continue-Drop.aspx What is the point of studying global warming if we idly stand by and allow tabloid media to control the message? I think sites like this are an excellent start at again making clear to the general population what science really says about AGW.
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  25. robhon at 04:18 AM on 13 March, 2010 Here's a timely article looking at a number of polling results and taking from them some longer term speculations on where public perception is headed. Well worth a read, some very interesting comparisons: "An Ipsos-Mori poll in the UK released in February showed those thinking climate change is "definitely" happening had fallen from 44% to 31% in the year to the middle of January. A Populus poll for the BBC conducted on 3-4 February revealed that 25% of people didn't think global warming was happening, up from 15% in November. Look at that the other way round and the Ipsos-Mori poll showed 91% of people accepted climate change was happening, and the Populus poll 75%. The difference is probably due to the former poll not including people over 65, who are significantly more sceptical, while the latter was conducted at the peak of negative news coverage about climate science. As ever with polls, the different phrasing of questions matters too. Nonetheless, confidence has fallen. Why? An obvious factor is the recent public relations disaster suffered by climate scientists, including both the leaked emails from the University of East Anglia and the false claim that all Himalayan glaciers could melt by 2035, which was included in the report of the Intergovernmental Panel on Climate Change (IPCC). But this is unlikely to be the whole story, as only 57% of those polled by Populus had heard these stories. Far more – 83% – had heard about, and were experiencing, an exceptionally cold winter. That's a pretty tangible opinion former, even if it is wrong, given the crucial difference between week-to-week weather and decade-to decade climate. More: http://www.guardian.co.uk/environment/blog/2010/mar/12/climate-change-belief-polls
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  26. dhogaza 48. You gave another - very strong - anecdotal response! Thank you.
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  27. doug_bostrom... Good call. I think you're right. It's not just a matter of tabloid media ruling the day. It's also a function of basic human nature. Dan Miller does an interesting talk where he discusses natural human responses to danger. The instinctual responses that move people to action. It's purely an intellectualized fear that most people can't grasp. http://fora.tv/2009/08/18/A_REALLY_Inconvenient_Truth_Dan_Miller#fullprogram (click section 9)
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  28. Ned (#69) gives an admirable defence of his teacher and probably mentor. Prof. Trenberth seems to be sincere too. But what he says is that we just do not know enough. How does he jump from there to an affirmative belief if any kind is intellectually suspect. Anyone here who knows enough about Christopher Landsea who appears to have a scientific disagreement with Prof. Trenberth. Is Mr. Landsea dishonest by any chance? Just curious as a non-specialist beholding professional disagreement which, if it was only academic, it would be interesting and essentially none of my business. Given the stakes however, permit me to be very skeptical.
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  29. 1077 said: “Thus the poll should yield an equal percentage of liberal and conservative sympathizers on both sides of the controversy.” Let’s suppose that such a poll would achieve these results. I am to infer that this would show that indeed it doesn’t matter which side of politics people sit, it would mean that belief climate change is apolitical? In principle it sounds great...but when you have results such as this: http://www.gallup.com/poll/126563/conservatives-doubts-global-warming-grow.aspx It highlights the danger of siding the science with political agenda, and destroys the neutrality that scientists generally are perceived as having in their work. Say political party X offers more funding for a particular science project (not even climate science related), or better, some more funding for hospitals, then I would expect a survey would show a spike in doctors that have a political preference that is higher for party X. The results would not be an inconvenience, but would be highly spurious. Maybe i’m lost with what you’re talking (perhaps you flatter my intelligence) but what exactly is a scientific poll, and what interesting answers are we to expect from it?
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  30. People who have taken a political stance on what is really a matter of scientific fact have often been wrong footed. How many ended up on the wrong side of reality after backing Lysenko or Sir Cyril Burt? Let honest science investigate the nature of the physical world and let politics address the allocation of resources.
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  31. 1077 writes: Ned (#69) gives an admirable defence of his teacher and probably mentor. No, I've never met Trenberth face to face as far as I know. We used his textbook in one or another of the climate modeling courses I took in graduate school. Prof. Trenberth seems to be sincere too. But what he says is that we just do not know enough. How does he jump from there to an affirmative belief if any kind is intellectually suspect. Anyone here who knows enough about Christopher Landsea who appears to have a scientific disagreement with Prof. Trenberth. Is Mr. Landsea dishonest by any chance? I'm sorry if I wasn't clear, though I tried hard to be clear in my comment. There's nothing wrong with disagreeing about the science; the problem is with claiming that someone secretly believes the opposite of what he clearly and adamantly says he believes.
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  32. Ned (#69), it seems that I am not making myself clear. Let me try again. Counting the number of scientists (or even the number of published papers) is meaningless. In science, quality is more important than quantity. One Gallileo prevails over a multitude of Urban VIIIs. Real science cannot be settled. Anyone who makes statements such as "the science is settled" or "unequivocal" betrays his lack of understanding of what science is about. Such people are anti-science. When I hear such statements coming from Al Gore I don't get upset because Al does not pretend to be a scientist. Prominent "scientists" such as Watson and Trenberth should avoid publishing such exaggerated claims if they want to retain the respect of their peers or the general public. doug_bostrom (#65), I could have gone on at length about Trenberth's paper but it would not have been relevant to my point. The quote I chose demonstrates that Dr. Trenberth lacks objectivity in relation to "global warming" which he should realise is not scientific truth. It is a theory and a shaky one at that.
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  33. Galileo is particularly famous in the skeptics quarters. I find it a bit superficial. The first thing that people usually overlook is that Galileo was not the first to think of an eliocentric solar system. What i mean is that new ideas do not come from nowhere, it's more like an ongoing cultural process which end up in a clear statement (theory) or new strong evidence. What Galileo did is a measurement with a new and powerful instrument he developed. The second is that Galileo is so beloved for having been harassed not by other scientist but by the Catholic Church, he confronted a religious belief. Although he put is life at risk, from a modern scientific point of view it was a relatively easy game. The third is that Arrhenius had a similar fate. After Angstrom criticism, a scientific one this time, his idea was dismissed for decades. In the long run, the scientific self-correcting method prevailed. This is indeed the very same fate any new idea "deserves" in the highly sceptical scientific community. Galileo Galilei is indeed one of the best minds in the whole history of humans. He deserves much more than the trivial and scientifically irrelevant fame for the dispute with the Church. He is often called "the Father of Modern Science" and Stephen Hawking once said that Galileo "perhaps more than any other single person, was responsible for the birth of modern science". He studied the great ellenistic scientists and revived and applied their scientific method. He was a giant and it's really depressing seeing his name so badly invoked. I need to apologize for this offtopic disgression but i hope that sooner or later we will see his name linked to his more important findings and contribution to science.
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  34. gallopingcamel writes: Real science cannot be settled. Anyone who makes statements such as "the science is settled" or "unequivocal" betrays his lack of understanding of what science is about. Such people are anti-science. This is a problem of language (what does it mean to be "settled"?) The theory of AGW is very, very analogous to the theory of plate tectonics. Both of them are "settled" in the sense that they appear necessary to explain all the evidence of the world around us. Both of them are complex theories that can't be reduced to a couple of equations or simple statements, so they differ from (say) Maxwell's work on electromagnetism or Newton's laws. The details of our understanding of AGW and plate tectonics will continue to evolve over time (and yes, evolution itself is another example of a theory analogous to AGW). But neither AGW nor plate tectonics is likely to be overturned by new discoveries. That's what Trenberth means when he says "It is absolutely certain that carbon dioxide is a greenhouse gas and produces warming". I dislike the term "settled" because it suggests that there's nothing left to learn. (And has any scientist actually used the expression "the science is settled"? Pretty much every reference to it is from "skeptics"....)
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  35. There seems to be some misunderstanding as to what scientific consensus means. Nobody has polled the members of scientific associations and ranked their opinions to come up with a consensus. The consensus model of Earth climate slowly emerged from all the research being done. Study after study being reviewed and published. It is not a consensus of opinion but of research results. When considering these results as a big picture, a certain model can be defined, which is supported by an overwhelming preponderance of evidence, very much like in Ned's plate tectonics comparison. Within that model, some stuff will be settled, some will have a certain level of uncertainy or unresolved inconsistencies, some will be the subject of much debate and some will even be unknown. This applies to Quantum Theory as well as Evolution or Climatology. None of it is "proven true." Science does not provide truth. Truth is vocabulary appropriate in the law, theology, politics and so forth. In science, the word truth should be limited to the qualification of mathematical facts, really. Science attempts to understand reality. It does that by approximating with models, mind constructs. Since it is well known that these are approxiamtions, "truth" is out of the question. Scientific consensus is in fact a strong statement of validity. It means that a very large body of research points in a certain direction, not that a number of people in positions of influence agree to make a model the "chief" model. There is no choice as to what the model is: it is dictated by the evidence. There are numerous theories very much shakier than the consensus model of Earth climate. It would be very interesting to subject theories used in psychology, medicine, economics and many other fields to the same level of scrutiny applied to climate science and see how they hold up. I would also be interested to see how the experts in these fields would react when faced with media campaigns aimed at having their expertise challenged by amateurs, their work and reputation attacked, and throwing each and every word they write or say into endless spins of misquote and misinterpretation.
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  36. Following up on Philippe's comment about the consensus being based on evidence rather than simple voting, here is a link to Naomi Oreskes's new talk, which addresses that topic right from the start. She even responds to skeptics who bring up Galileo as a counterpoint. Other commenters have pointed to this talk repeatedly, but some other commenters seem to not have bothered to watch it. It would be more productive if some of the commenters who deny the role of consensus in science, were to react specifically to Oreskes's points.
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  37. Phillippe Chantreau writes: There seems to be some misunderstanding as to what scientific consensus means...The consensus model of Earth climate slowly emerged from all the research being done. Study after study being reviewed and published. It is not a consensus of opinion but of research results Brilliant! - about time somebody highlighted this. The denialists represent the consensus that we talk about basically as meaning that we are saying that a majority of scientists believe a certain thing. All they did with the Oregon petition was craft a cleverly weasel worded statement, as I pointed out earlier in these comments, that enabled them to say 'look - this huge number of "scientists" don't agree with the consensus' and Bob's your Uncle - an enduring denier meme, supremely and successfully misleading to the general public, was born. Perhaps we need to emphasise that it is the enormous weight of evidence and research that is the "consensus" view.
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  38. I'd go further and highlight thay any scientific field that is studied enough will, at some point, see the emergence of some level of consensus, unless no significant progress is being made in the understanding of that field. Scientific consensus is the normal extension of progressing knowledge.
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  39. The point of science is not consensus, it is prediction. If a theory makes good predictions, it will naturally cause the birth of a consensus around it. However, forming a consensus prior to the ability to make predictions doesn't really tell you much. If one treats the GCMs as hypotheses and looks at how effective, they would've been at predicting the changes in temperatures over the last 100 years, the only reasonable answer is that they aren't very good at all. They couldn't have predicted the temperature increase from 1910-1945, would've done OK for about 1945-1998, and pretty poorly for the last 10-15 years. Since the GCMs were calibrated using the data they are the most effective at "predicting", that doesn't really tell us much. Cheers, :)
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  40. The point of science is not consensus, it is prediction. If a theory makes good predictions, it will naturally cause the birth of a consensus around it. However, forming a consensus prior to the ability to make predictions doesn't really tell you much.
    That's exactly how the mainstream climate science consensus came about. Read Spencer Weart's "The Discovery of Global Warming". Your second paragraph simply demonstrates that you have a lot to learn about GCMs. This: "Since the GCMs were calibrated using the data they are the most effective at "predicting", that doesn't really tell us much." Simply tells us you don't know how they work. And the rest of the paragraph is a blend of speculation. "couldn't've predicted the temperature increase from 1910-1945"? If it were possible to predict changes in solar insolation and frequency of volcanic eruptions decades in the future, well, yes, they *could* have.
    pretty poorly for the last 10-15 years
    Nope. With proper error bars, the models have done fine. Individual model runs show the kind of variability we see in real climate, including periods of faster and slower warming. I suspect you're one of those that believe that since the *average* of many model runs shows "smooth, monotonic warming" that each model run shows the same (they don't) or that models "predict" that climate should do the same (they don't). And my guess is that you're one of those who ignore error bars (which grow rapidly as the timeframe under consideration shrinks) or has been sucked in by baloney such as seen over at lucia's blog. Arguments such as you make have no traction in the scientific community for a reason, I'm afraid - they're just wrong.
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  41. shawnhet, very crude claims indeed. The consesus has indeed formed around tons of data, which is what you should expect. The GCMs are not the hypotheis, they're just calculations; it should be quite obvious that model calculations are not a theory, and they never will. But anyways, the ability of GCMs to reproduce climate has been assessed by scientists and the consesus around them, as yo ask, is clear. They reproduce the rise in temperature of the first half of the last century and even the last ten years, at least if you look at the results not as a yearly point by point match but as an overall trend. And no, GCM are not calibrated to the same data they reproduce, this is simply wrong. They are able to describe many other things you overlooked. Then, following your first claim the logical conclusion is that there is consesus both on the AGW theory and on the ability of GCM. What is surprisingly missing is your consensus.
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  42. shawnhet, if you want to argue about the predictive power of climate models, the appropriate thread is Models are unreliable.
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  43. shawnhet at 05:15 AM on 15 March 2010 It's always better to argue from an informed position. Get the background information you need on climate models here: Simple models of climate change General circulation models of climate
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  44. The only type of disagreement that counts is science is published papers. After your paper gets through peer review and is more widely viewed it stands or not. I would the expect the people who created the petition to know this.
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  45. dhogaza:And the rest of the paragraph is a blend of speculation. "couldn't've predicted the temperature increase from 1910-1945"? If it were possible to predict changes in solar insolation and frequency of volcanic eruptions decades in the future, well, yes, they *could* have. I think you'll find that if one compares the proposed forcing for the 1910-45 period to the observed temperature that the climate was behaving as though it was subject to more forcing that we currently accept. I know that one can always fall back on the error bars because they are so wide, but that doesn't really help the idea that the GCMs are good predictors of climate. Riccardo, "The GCMs are not the hypotheis, they're just calculations; it should be quite obvious that model calculations are not a theory, and they never will." I find this a fascinating idea. I was always taught that the scientific method proceeded by proposing a hypothesis that allowed testable predictions to be made. If the GCMs are not hypotheses, then by what reason are they a part of the scientific method. Surely the fact that there are more than one GCM establishes that the calculations can be done more than one way(IOW they are not simply some automatic process that makes no difference to the predictions). If the GCMs are not hypotheses, should we just ignore them from a scientific standpoint? No, I don't think so. We should just accept them as what they are: individual hypotheses about the nature of the climate. We can then use them to make a variety of tests about the real world and see which of them(if any) match the real world behavior and how often they can do so. "And no, GCM are not calibrated to the same data they reproduce, this is simply wrong." Rather than spend a lot of time going over this issue, Lucia does a good job of discussing model tuning here(about halfway down the page). http://rankexploits.com/musings/2009/how-far-off-are-the-ar4-aogcms/ "They are able to describe many other things you overlooked." Again, I don't care what they describe, its what they predict that matters IMO. "Then, following your first claim the logical conclusion is that there is consesus both on the AGW theory and on the ability of GCM. What is surprisingly missing is your consensus." Why do I need a consensus? The fact is that I can do just about as good a job as the GCMs by assuming a zero feedback model with a strong influence from the PDO. This matches the periods where the GCMs do less well better and the most recent period too. The point is that regardless of the number of people that think that hypothesis X is valid, until we can come up with an unambiguous test that separates if from hypothesis Y, we can't scientifically say that X is better than Y. Cheers, :)
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  46. shawnhet, "I was always taught that the scientific method proceeded by proposing a hypothesis that allowed testable predictions to be made." Indeed. What has this has to do with GCM? This is a quite common misunderstanding of the meaning of model. They are "just" a mathematical expression of more or less complicated physical laws, the theory is the big picture. Think about Arrhenius, his theory is the same we debating today but the model calculations are enormously different. Obviously we do not ignore GCM and their ability, but it's a different issue than the theory itself. They do a reasonable job in describing how the earth climate works, unless as Lucia says you think that "about 0.2 *C/decade" is a whole lot away from the estimated 0.16 °C/decade. It really surprises me that you "don't care what they describe". How do you test a model if not with as many as possible actual data and, eventually, new and still unrecognized effects? The future is uncertain by definition, especially when it will be at least in part decided by human actions and unpredictable natural forces. If, say, the sun decides to slow down for some decades, will it disprove the ability of GCM? No, of course, you'll plug in the new data and run them again, but it's not a prediction. Indeed, climatologists do not the word "predictions", the say "projections". "I can do just about as good a job as the GCMs by assuming a zero feedback model with a strong influence from the PDO." You sure could do it, but do you have any solid physical basis for it or you're just playing with numbers? As we all know, a correlation is just a hypothesis , then comes the physics. A model works differently, you plugin the physics and see the outcome. This is exactly why we CAN scientifically say that X is better than Y, just a correlation would not suffice.
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  47. (#88) So true, Philippe; "...any scientific field that is studied enough will, at some point, see the emergence of some level of consensus, unless no significant progress is being made..." From my viewpoint as someone with a degree in Philosphy: at one point 'Natural Philosophy' was _all_ of science. As consensus accumulated in various aspects we got Chemistry, Physics, Math, Biology, Engineering, etc. Now the only questions really left under the Philosophy tent are those that people are still arguing over after thousands of years, like 'why act justly when you won't get caught', 'what is the nature of the universe', and 'tastes great vs. less filling!'
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  48. Riccardo: This is a quite common misunderstanding of the meaning of model. They are "just" a mathematical expression of more or less complicated physical laws, the theory is the big picture. Think about Arrhenius, his theory is the same we debating today but the model calculations are enormously different. No, the GCMs are, in fact, the hypotheses. They make different(hopefully more) predictions than Arrhenius did. I am not sure how long Arrhenius thought it would take the climate system to equilibrate to an addition of CO2, but I very much doubt that it was as long as is proposed under the current theory. This is not that different than, for instance, Newton and Einstein's theories of gravities. In terms of the big picture(ie the vast majority of circumstances), their predictions are essentially, however, for some phenomena the predictions are different. Hence, different predictions mean different hypotheses. "It really surprises me that you "don't care what they describe". How do you test a model if not with as many as possible actual data and, eventually, new and still unrecognized effects? The future is uncertain by definition, especially when it will be at least in part decided by human actions and unpredictable natural forces. If, say, the sun decides to slow down for some decades, will it disprove the ability of GCM? No, of course, you'll plug in the new data and run them again, but it's not a prediction. Indeed, climatologists do not the word "predictions", the say "projections"" We may be using the word "describe" differently here, so I'll be a bit more clear. Let's assume arguendo that it is possible both to describe 1.the current climate as either the result of the forcing, strong feedbacks, and weak natural variation or 2. as the result of forcing, weak feedback and strong natural variation. If we assume, 1 and 2 are both equally good descriptions of the climate, then what? How do we know which one is valid? The answer is, we try to find distinct predictions of 1 & 2 to falsify one or both. We don't say that because we can describe the climate in one or the other terms that we have answered the question. ""I can do just about as good a job as the GCMs by assuming a zero feedback model with a strong influence from the PDO." You sure could do it, but do you have any solid physical basis for it or you're just playing with numbers? As we all know, a correlation is just a hypothesis , then comes the physics. A model works differently, you plugin the physics and see the outcome. This is exactly why we CAN scientifically say that X is better than Y, just a correlation would not suffice." But you can't just plug in the numbers, you first have to build the framework (I would say hypothesis) that you plug the numbers into. As to the relationship between correlation and mechanism, mechanisms are great, but they are not necessary to perform science. I do not need to know how the PDO influences climate to predict that, for example, each unit on the PDO index raises/lowers the global temperature by X deg. C. The very complexity that requires the construction of climate computer models makes the simple physics, obviously makes the kind of mechanism you ask for nearly impossible too. The fact that climate is complex, however, doesn't preclude there from being detectable relationships between small parts of the system(like the PDO index) and the whole. Cheers, :)
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  49. shawnhet, climate models are a description of how the climate works. You plug in the physics and chemistry of the atmosphere, land and oceans, and let them describe how they evolve. They can be (and actually are) used for other planets as well, or to describe the climate milions of years ago or to predict the impact of eventually known or assumed natural forcings. No AGW here. The anthropogenic climate change theory, instead, tells us that current human emission patterns will result in a significant impact on our climate. It can be tested in many different ways and climate models are a usefull tool, but the theory is not a priori included. In your example a PDO driven climate change is the theory that need to be tested. To test it you could do several things including modelling it. You should work out the physics of the PDO and its interactions with the other pieces of the picture and see the results. Again, your model would be a tool not the theory itself.
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  50. Riccardo, you can't just plug the physics in. You have to program a wide variety of parameters in too. Such parameterizations are essentially just guesses as to how the real world works. Wikipedia has a decent explanation of the process here: http://en.wikipedia.org/wiki/Parametrization_(climate) "In your example a PDO driven climate change is the theory that need to be tested. To test it you could do several things including modelling it. You should work out the physics of the PDO and its interactions with the other pieces of the picture and see the results. Again, your model would be a tool not the theory itself." There is nothing wrong with trying to figure out the physics of (whatever causes the PDO), however, this is not necessary to make predictions about its effects. Mechanisms are desirable because they allow more specific and numerous predictions to be made(and, hence, better hypotheses as well). But a hypothesis can be perfectly valid even if it could potentially be improved by the development of a decent mechanism. For the record, though, it is certainly possible to imagine many mechanisms whereby shifts in PDO can affect the broader climate(cloud cover and ocean currents, for instance). Cheers, :)
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